Re: [Elecraft] NOT the feedline

[Ed Pflueger]

I have a HY-Gain VB-66DX and 1.4 is the normal case basically across the whole 
band.  I must be messing up somewhere, even the KPA1500 likes it.  I have never 
run it over 1200 Watts on 6 meters and never requires over 30 watts drive to 
obtain 1200 out.  I have three feet of 213U from amp to Palstar HF-AUTO (Bypass 
Mode), 70ft. of 9913 from the Palstar to a DX-Engineering 8 position Antenna 
switch, to my lightening protection and the final trip of 40ft of 213U to the 
antenna.  The antenna is actually 10ft. above my HY-GAIN TH11 which also does 
not require a tuner.  The Palstar is my antenna switch essentially but I do 
need it on my HY-GAIN HY-TOWER only on 160 and 80 meters when needed.

That's the end of my good luck story.  LOL

Ed..AB4IQ 

-Original Message-
From: elecraft-boun...@mailman.qth.net 
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob McGraw K4TAX
Sent: Tuesday, June 2, 2020 10:27 AM
To: Mark Goldberg 
Cc: Elecraft Mailing List 
Subject: Re: [Elecraft] NOT the feedline

As a rule, if one needs a tuner to get a good match on 6M, I'd say they need to 
look carefully at their antenna system.  My 6M yagi shows less than 1.5:1 over 
the lower 2 MHz of the band, 50.0 - 52.0 MHz.  The lowest SWR occurs at 50.2 
with a Z value of 42 ohms and an X value of 0.0.  Of course higher gain 
antennas typically have a bit less bandwidth, but still, the lower 1 MHz should 
be totally usable without a tuner.

Besides, tuners only make the transmitter happy and the added feed line loss 
due to SWR still remains.

73

Bob, K4TAX


On 6/2/2020 1:09 AM, Mark Goldberg wrote:
> I want to mention that my LDG AT-600Pro has a minimum capacitance that 
> is too high for a good match to my antenna on 6 meters. Certainly 
> seems like removing the Ten Tec tuner would be a good thing to try.
> Can you open the Ten Tec tuner and use an IR thermometer to monitor 
> the components? I don't know anything about it's construction. You 
> could see them heating up.
>
> Just running medium power of maybe 500W would slow things down and let 
> you see the SWR increasing before the amp trips. That would confirm 
> that something is heating up vs arcing.
>
> 73,
>
> Mark
> W7MLG
>
> On Mon, Jun 1, 2020 at 9:01 PM Bob McGraw K4TAX  <mailto:rmcg...@blomand.net>> wrote:
>
> Plus there is L1 which is 0.3uH in the circuit and C7 and C8 in the
> circuit when in the bypass position.  This does not allow the tuner,
> even in bypass mode, to work well as an antenna switch on 6M.
>
>   The capacitors in question are not rated for the RF current
> experienced under certain load Z conditions.  They heat, change
> value,
> and the SWR creeps up.  Allow them to cool and the SWR is back to the
> starting point.I usually tweaked mine such that the SWR
> started off
> a bit high, came down as I transmitted and if transmitting a bit
> longer
> the SWR increased.   Later I got tired of this and changed the
> group of
> disk ceramic caps to 470 pf Russian doorknob caps.  Problem solved.
>
> 73
>
> Bob, K4TAX
>
>
> On 6/1/2020 10:08 PM, Jim Brown wrote:
> > his might be it, Peter. ! I've used (and loved) the Ten Tec 229 and
> > 238 tuners, but some of their fixed capacitors are under-rated for
> > power. This is fairly well known among Ten Tec users, so I read
> about
> > it somewhere and replaced those in my tuners with caps having
> higher
> > power ratings.
>
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Re: [Elecraft] NOT the feedline

[Bob McGraw K4TAX]

The Tentec 238 tuner does have some values of L and C components in the 
circuit when in the Bypass mode.  These are L1 which is 0.3uH and C7 & 
C8 which are 250 pf in series.   The tuner is designed for use between 
1.8 and 30 MHz.   Thus I would not advise using it as an antenna switch 
on 50 MHz and certainly not to resolve a match on 50 MHz.


You may find that adjustment in the ladder line length {just a couple of 
ft, more or less, for 6M}  will aid in the LDG tuner finding a better 
match with existing component values and parasitic capacitance.


73

Bob, K4TAX



On 6/2/2020 10:53 AM, Mark Goldberg wrote:
I failed to mention, my antenna system is a 300 ft long horizontal 
loop fed by ladder line with a homebrew two core switchable 1:1 or 4:1 
Guanella current mode Balun. The Balun has a measured return loss of 
about 32 dB at 50 MHz with a 200 ohm resistive load. That was 
surprisingly good, but confirmed with a calibrated VNA. Yes, I spent 
some time with Jerry Sevick's book.


The antenna is not deluxe for 50 MHz, but it is all I have. It's just 
so happens that only small values are required in the tuner to match 
it, and the LDG tuner parasitic capacitance it too high even when in 
bypass mode. I expect it is difficult to build a physically large high 
power tuner and keep the parasitics down, so the Ten Tec may have 
similar issues. As I said, I know nothing about it. From Peter's most 
recent email, this may be the case.


73,

Mark
W7MLG

On Tue, Jun 2, 2020 at 8:26 AM Bob McGraw K4TAX > wrote:


As a rule, if one needs a tuner to get a good match on 6M, I'd say
they need to look carefully at their antenna system.  My 6M yagi
shows less than 1.5:1 over the lower 2 MHz of the band, 50.0 -
52.0 MHz.  The lowest SWR occurs at 50.2 with a Z value of 42 ohms
and an X value of 0.0.  Of course higher gain antennas typically
have a bit less bandwidth, but still, the lower 1 MHz should be
totally usable without a tuner.

Besides, tuners only make the transmitter happy and the added feed
line loss due to SWR still remains.

73

Bob, K4TAX


On 6/2/2020 1:09 AM, Mark Goldberg wrote:

I want to mention that my LDG AT-600Pro has a minimum capacitance
that is too high for a good match to my antenna on 6 meters.
Certainly seems like removing the Ten Tec tuner would be a good
thing to try. Can you open the Ten Tec tuner and use an IR
thermometer to monitor the components? I don't know anything
about it's construction. You could see them heating up.

Just running medium power of maybe 500W would slow things down
and let you see the SWR increasing before the amp trips. That
would confirm that something is heating up vs arcing.

73,

Mark
W7MLG


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Re: [Elecraft] NOT the feedline

[Mark Goldberg]

I failed to mention, my antenna system is a 300 ft long horizontal loop fed
by ladder line with a homebrew two core switchable 1:1 or 4:1 Guanella
current mode Balun. The Balun has a measured return loss of about 32 dB at
50 MHz with a 200 ohm resistive load. That was surprisingly good, but
confirmed with a calibrated VNA. Yes, I spent some time with Jerry Sevick's
book.

The antenna is not deluxe for 50 MHz, but it is all I have. It's just so
happens that only small values are required in the tuner to match it, and
the LDG tuner parasitic capacitance it too high even when in bypass mode. I
expect it is difficult to build a physically large high power tuner and
keep the parasitics down, so the Ten Tec may have similar issues. As I
said, I know nothing about it. From Peter's most recent email, this may be
the case.

73,

Mark
W7MLG

On Tue, Jun 2, 2020 at 8:26 AM Bob McGraw K4TAX  wrote:

> As a rule, if one needs a tuner to get a good match on 6M, I'd say they
> need to look carefully at their antenna system.  My 6M yagi shows less than
> 1.5:1 over the lower 2 MHz of the band, 50.0 - 52.0 MHz.  The lowest SWR
> occurs at 50.2 with a Z value of 42 ohms and an X value of 0.0.  Of course
> higher gain antennas typically have a bit less bandwidth, but still, the
> lower 1 MHz should be totally usable without a tuner.
>
> Besides, tuners only make the transmitter happy and the added feed line
> loss due to SWR still remains.
>
> 73
>
> Bob, K4TAX
>
>
> On 6/2/2020 1:09 AM, Mark Goldberg wrote:
>
> I want to mention that my LDG AT-600Pro has a minimum capacitance that is
> too high for a good match to my antenna on 6 meters. Certainly seems like
> removing the Ten Tec tuner would be a good thing to try. Can you open the
> Ten Tec tuner and use an IR thermometer to monitor the components? I don't
> know anything about it's construction. You could see them heating up.
>
> Just running medium power of maybe 500W would slow things down and let you
> see the SWR increasing before the amp trips. That would confirm that
> something is heating up vs arcing.
>
> 73,
>
> Mark
> W7MLG
>
>
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Re: [Elecraft] NOT the feedline

[Bob McGraw K4TAX]

It is correct that there is no such thing as a breakdown voltage, as 
stated earlier. This becomes obvious since the units are given as V/m, 
which is represents Volts per meter, or Electric Field strength.


Also, unless one is measuring the field in between two plane parallel 
metallic plates, the Electric Field will, in general, not be uniform, 
I.e., the field strength (the amount of "pull" on an electron), will 
vary with position. This shape does matter, and sharply pointed emitters 
can cause breakdown at values considerably less than the maximum 
measured in a uniform field.


The Volts/meter relationship is also pressure-dependent, and this 
relationship goes nonlinear at low pressures (not enough charge 
carriers) following Paschen's law 
. It also varies with 
humidity and other contaminants, which usually increase arcing.


73

Bob, K4TAX


On 6/2/2020 8:54 AM, j...@kk9a.com wrote:


The RMS voltage for 1000 watts into a perfect load is <250 volts. I 
suspect that Tony's 4,000 voltage limit is closer to what a quality 
PL-259 can actually handle. If the PL-259 is arcing, there is 
something very wrong with either the connector, the weatherproofing or 
the antenna.


John KK9A





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Re: [Elecraft] NOT the feedline

[Peter Dougherty]

Just to clarify, I was **NOT** using the tuner to tune the 6m antenna
system. I was using it as a coax switch, so I could keep the KPA-1500
powered down (silencing the very noisy PSU fan) and still be able to receive
6m as well as other bands. 

I need the room to be quiet since my XYL is working-from-home a few feet
away from me in the same room, and the KPA's power supply fan is bothersome
to both her and me.

Ideally, the KPA-1500 should be able to default to either ANT-1 or ANT-2 in
power-down mode but that is not the case. So I need a quiet alternative. I'm
not a fan of tuners of any kind. 

In any event, the TT-238 is out of line now and the SWR problem is
MARGINALLY better on the KPA-1500. It's still showing a higher SWR than the
antenna analyzer measured but it hasn't folded back yet.


 - pjd

-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Mark Goldberg
Sent: Tuesday, June 2, 2020 2:10 AM
To: Bob McGraw K4TAX 
Cc: Elecraft Mailing List 
Subject: Re: [Elecraft] NOT the feedline

I want to mention that my LDG AT-600Pro has a minimum capacitance that is
too high for a good match to my antenna on 6 meters. Certainly seems like
removing the Ten Tec tuner would be a good thing to try. Can you open the
Ten Tec tuner and use an IR thermometer to monitor the components? I don't
know anything about it's construction. You could see them heating up.

Just running medium power of maybe 500W would slow things down and let you
see the SWR increasing before the amp trips. That would confirm that
something is heating up vs arcing.

73,

Mark
W7MLG

On Mon, Jun 1, 2020 at 9:01 PM Bob McGraw K4TAX  wrote:

> Plus there is L1 which is 0.3uH in the circuit and C7 and C8 in the 
> circuit when in the bypass position.  This does not allow the tuner, 
> even in bypass mode, to work well as an antenna switch on 6M.
>
>   The capacitors in question are not rated for the RF current 
> experienced under certain load Z conditions.  They heat, change value, 
> and the SWR creeps up.  Allow them to cool and the SWR is back to the
> starting point.I usually tweaked mine such that the SWR started off
> a bit high, came down as I transmitted and if transmitting a bit longer
> the SWR increased.   Later I got tired of this and changed the group of
> disk ceramic caps to 470 pf Russian doorknob caps.  Problem solved.
>
> 73
>
> Bob, K4TAX
>
>
> On 6/1/2020 10:08 PM, Jim Brown wrote:
> > his might be it, Peter. ! I've used (and loved) the Ten Tec 229 and
> > 238 tuners, but some of their fixed capacitors are under-rated for 
> > power. This is fairly well known among Ten Tec users, so I read 
> > about it somewhere and replaced those in my tuners with caps having 
> > higher power ratings.
>
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> marklgoldb...@gmail.com
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Re: [Elecraft] NOT the feedline

[Bob McGraw K4TAX]

As a rule, if one needs a tuner to get a good match on 6M, I'd say they 
need to look carefully at their antenna system.  My 6M yagi shows less 
than 1.5:1 over the lower 2 MHz of the band, 50.0 - 52.0 MHz.  The 
lowest SWR occurs at 50.2 with a Z value of 42 ohms and an X value of 
0.0.  Of course higher gain antennas typically have a bit less 
bandwidth, but still, the lower 1 MHz should be totally usable without a 
tuner.


Besides, tuners only make the transmitter happy and the added feed line 
loss due to SWR still remains.


73

Bob, K4TAX


On 6/2/2020 1:09 AM, Mark Goldberg wrote:
I want to mention that my LDG AT-600Pro has a minimum capacitance that 
is too high for a good match to my antenna on 6 meters. Certainly 
seems like removing the Ten Tec tuner would be a good thing to try. 
Can you open the Ten Tec tuner and use an IR thermometer to monitor 
the components? I don't know anything about it's construction. You 
could see them heating up.


Just running medium power of maybe 500W would slow things down and let 
you see the SWR increasing before the amp trips. That would confirm 
that something is heating up vs arcing.


73,

Mark
W7MLG

On Mon, Jun 1, 2020 at 9:01 PM Bob McGraw K4TAX > wrote:


Plus there is L1 which is 0.3uH in the circuit and C7 and C8 in the
circuit when in the bypass position.  This does not allow the tuner,
even in bypass mode, to work well as an antenna switch on 6M.

  The capacitors in question are not rated for the RF current
experienced under certain load Z conditions.  They heat, change
value,
and the SWR creeps up.  Allow them to cool and the SWR is back to the
starting point.    I usually tweaked mine such that the SWR
started off
a bit high, came down as I transmitted and if transmitting a bit
longer
the SWR increased.   Later I got tired of this and changed the
group of
disk ceramic caps to 470 pf Russian doorknob caps.  Problem solved.

73

Bob, K4TAX


On 6/1/2020 10:08 PM, Jim Brown wrote:
> his might be it, Peter. ! I've used (and loved) the Ten Tec 229 and
> 238 tuners, but some of their fixed capacitors are under-rated for
> power. This is fairly well known among Ten Tec users, so I read
about
> it somewhere and replaced those in my tuners with caps having
higher
> power ratings.

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Re: [Elecraft] NOT the feedline

[john]

The RMS voltage for 1000 watts into a perfect load is <250 volts. I  
suspect that Tony's 4,000 voltage limit is closer to what a quality  
PL-259 can actually handle. If the PL-259 is arcing, there is  
something very wrong with either the connector, the weatherproofing or  
the antenna.


John KK9A




tony.kaz N2Tk wrote:

Walter,
Yes, the UHF connector may be rated at 500V, but in practice they  
handle >4KV. The voltage limit is set by the air gap between the  
center pin and the shield. I have not had a PL-259 arc over.

73,
N2TK, Tony

-Original Message-
From: elecraft-bounces at mailman.qth.net mailman.qth.net> On Behalf Of Walter Underwood

Sent: Monday, June 1, 2020 6:32 PM
To: Elecraft Reflector 
Subject: Re: [Elecraft] NOT the feedline

Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating  
for a UHF connector. Type N connectors are rated at 1500 V peak.


wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

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Re: [Elecraft] NOT the feedline

[N2TK via Elecraft]

Walter,
Yes, the UHF connector may be rated at 500V, but in practice they handle >4KV. 
The voltage limit is set by the air gap between the center pin and the shield. 
I have not had a PL-259 arc over.
73,
N2TK, Tony

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Walter Underwood
Sent: Monday, June 1, 2020 6:32 PM
To: Elecraft Reflector 
Subject: Re: [Elecraft] NOT the feedline

Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating for a UHF 
connector. Type N connectors are rated at 1500 V peak.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jun 1, 2020, at 3:17 PM, George Kidder  wrote:
> 
> One of my antennas is a commercial "G5RV" fed with 33' of 450 ohm ladder 
> line, terminated in a PL-259 pair, with coax from there to the shack.  
> Apparently this combination results in very high RF voltage at the PL-259, 
> and it arcs over at 1000 W (not from an Elecraft amp!).  This combo goes wild 
> when I attempt high power on 80M, although it is stable at 100 W.  Just 
> another thing to watch out for!
> 
> 73 - George, W3HBM
> 
> On 6/1/2020 5:59 PM, Ted Edwards W3TB wrote:
>> [This message came from an external source. If suspicious, report to 
>> ab...@ilstu.edu<mailto:ab...@ilstu.edu>]
>> 
>> I am following this with great interest.
>> Like Alan G0GNX, I also use an OCF, RG-8X out to the current balun in 
>> this case, 300 ohm to the antenna.  K3, KPA-500 and KAT-500.
>> 
>> If I am running stations in a contest on 40m and also 80m CW, It "appears"
>> that my VSWR rises after a half hour and then the KAT-500 starts to 
>> try to spontaneously retune.  Doesn't happen on 20m and up.  This 
>> past weekend in CQ WPX, I reduced drive so that output was about 300 
>> watts and it all became tame.
>> 
>> I had thought that it was a heating of the RG-8X; then I changed my 
>> mind to the current balun from Radiowavz that is rated for 1.5 KW.  I 
>> think it is the balun just getting hot out there.  I had used a W2AU 
>> 4:1 balun with my OCF, which is a voltage balun but I didn't know 
>> about that -- for upwards of 40 years and with the Elecraft equipment 
>> for about 4 years since I got the amp/tuner.  I just switched to a 
>> current balun last year with one that I bought at Dayton.
>> 
>> I would have expected more problem with the voltage balun than with 
>> the current balun.  I could change back to the W2AU if needed.
>> 
>> Interesting stuff, so I am reading along.  And my thanks to all of you.
>> 
>> On Mon, Jun 1, 2020 at 4:42 PM Fred Jensen  wrote:
>> 
>>> Nearly same experience Bob:  Sloping V, 135 ft legs, from top of 80 
>>> ft tower fed with homemade 600 ohm open wire using a DX Engineering 
>>> 4:1 "balun" [a strange, usually misunderstood piece of electronic 
>>> apparatus often used for the wrong reasons] rated at 10 KW.  It 
>>> warmed up noticeably at 1.2 KW RTTY use.  It helps to remember that 
>>> one can saturate a ferrite core [especially when very hot] which 
>>> creates a racket reminiscent of a non-synchronous spark gap TX.
>>> 
>>> 73,
>>> Fred ["Skip"] K6DGW
>>> Sparks NV DM09dn
>>> Washoe County
>>> 
>>> On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:
>>>> Based on my experience, balun power ratings are for MATCHED 
>>>> conditions. It is rare that hams use a balun in a matched condition.
>>>>Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on 
>>>> the output, while a 4:1 balun should see 200 ohms on the output and 50
>>>> ohms on the input.   In the case of a resonant folded dipole, a 4:1
>>>> balun is typically operating in a nearly matched condition. All 
>>>> others combinations are unknown and random.
>>>> 
>>>> I run about 500 watts on all bands.  My baluns are rated at 5KW! It 
>>>> takes 3 or 4 big hunkin' pieces of ferrite to attain this power
>>>> level.   My 6 meter balun is a 1/2 wavelength electrically of RG-213.
>>>> No ferrite!
>>>> 
>>>> Buy or build a balun of your choice.  Using an IR temperature gun, 
>>>> measure the ambient temperature of the core.  Run about 1/2 rated 
>>>> power carrier for 30 to 60 seconds.  Measure the temperature again.
>>>> If it is warm to hot, this is RF producing heat.   And likely
>>>> continuing will produce core failure.   This is not a good balun for
>>>> your application.
>>>> 
>>>> One of my baluns w

Re: [Elecraft] NOT the feedline

[Mark Goldberg]

I want to mention that my LDG AT-600Pro has a minimum capacitance that is
too high for a good match to my antenna on 6 meters. Certainly seems like
removing the Ten Tec tuner would be a good thing to try. Can you open the
Ten Tec tuner and use an IR thermometer to monitor the components? I don't
know anything about it's construction. You could see them heating up.

Just running medium power of maybe 500W would slow things down and let you
see the SWR increasing before the amp trips. That would confirm that
something is heating up vs arcing.

73,

Mark
W7MLG

On Mon, Jun 1, 2020 at 9:01 PM Bob McGraw K4TAX  wrote:

> Plus there is L1 which is 0.3uH in the circuit and C7 and C8 in the
> circuit when in the bypass position.  This does not allow the tuner,
> even in bypass mode, to work well as an antenna switch on 6M.
>
>   The capacitors in question are not rated for the RF current
> experienced under certain load Z conditions.  They heat, change value,
> and the SWR creeps up.  Allow them to cool and the SWR is back to the
> starting point.I usually tweaked mine such that the SWR started off
> a bit high, came down as I transmitted and if transmitting a bit longer
> the SWR increased.   Later I got tired of this and changed the group of
> disk ceramic caps to 470 pf Russian doorknob caps.  Problem solved.
>
> 73
>
> Bob, K4TAX
>
>
> On 6/1/2020 10:08 PM, Jim Brown wrote:
> > his might be it, Peter. ! I've used (and loved) the Ten Tec 229 and
> > 238 tuners, but some of their fixed capacitors are under-rated for
> > power. This is fairly well known among Ten Tec users, so I read about
> > it somewhere and replaced those in my tuners with caps having higher
> > power ratings.
>
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Re: [Elecraft] NOT the feedline

[donovanf]

The Amphenol 83-1SP connector that many of us use is rated at 1000 
volts RMS, That well exceeds the voltage that most amateur 1500 
watt amplifiers can safely produce without much more severe internal 
damage to the amplifier. 


www.amphenolrf.com/media/downloads/305/C83-1sp.pdf 


73 
Frank 
W3LPL 




- Original Message -

From: "Jim Brown"  
To: elecraft@mailman.qth.net 
Sent: Tuesday, June 2, 2020 2:59:17 AM 
Subject: Re: [Elecraft] NOT the feedline 

On 6/1/2020 3:31 PM, Walter Underwood wrote: 
> Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating for a 
> UHF connector. 

The vast majority of HF stations with big power amps use UHF connectors 
throughout, and are without such problems as long as quality connectors 
are properly installed. The only problems I've ever had with connectors 
were the result the connectors being junk quality, and it hasn't been 
voltage breakdown. Rather I've had them fall apart, and I've had the 
center conductor melt. 

73, Jim K9YC 
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Re: [Elecraft] NOT the feedline

[Peter Dougherty]

It's a BIT better on ANT-2, but still faults out on occasion, and I'm not 
getting a true SWR reading. It is slightly more stable, though, to answer your 
question.

 - pjd

-Original Message-
From: Vic Rosenthal  
Sent: Tuesday, June 2, 2020 1:01 AM
To: Peter Dougherty 
Cc: Jack Brindle ; Elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline

Pardon me if this has already been covered, but do you have the same problem if 
you connect the antenna to ANT-2 on the KPA? I know you don’t want to do this 
permanently, but just as a test.

Victor 4X6GP 

> On 2 Jun 2020, at 3:47, Peter Dougherty  wrote:
> 
> Thanks for the reply, Jack. 
> 
> Here's a FULL summary of what is in the line at this moment from the jack on 
> up.
> 
> PL-259 (soldered, Amphenol 83-1SP as all are) to about 2 feet of RG-213 
> feeding into a Ten-Tec Tuner, which is being used only as an antenna switch 
> and is in bypass. This is needed because the power supply fan noise on the 
> KPA-1500 is just so overwhelming that I can only power it on when needed. I 
> am primarily an HF operator, so ANT-1 is reserved for my HF stack. If I put 
> the 6m antenna on ANT-2, I would need to keep the amp running. So everything 
> goes out on ANT-1, through the TT-238. From there, one feedline goes to the 
> HF stack and the other to the 6m output. It gets SLIGHTLY better if I go 
> directly from the KPA-1500 to the input box, as follows but I still 
> experience faults.
> 
> From there, a PL-259, and 7 or 8 feet of RG-213. Another PL-259, an Amphenol 
> barrel connector in the input box, PL259, then approximately 65 or 70 feet of 
> Commscope-branded LMR-400. PL-259 from that is connected to an Amphenol 
> SO-239 female-to-N-Male, the choke balun, then the driven loop element to the 
> antenna.
> 
> As of Tuesday morning this will change as follows. KPA-1500 ANT-1 out, PL-259 
> and about 40' of Davis BuryFlex out to the remote antenna switch at the base 
> of the HF stack. From there, about 25 more feet of BuryFlex, a barrel 
> connector then the LMR-400 up to the 6m antenna. This will basically just be 
> an experiment to see if there's any improvement; I'll be bypassing both the 
> old Ten-Tec tuner/switch and the inlet box, and routing via the HF signal 
> path and automatic antenna switch. Adding 65' of BuryFlex to the path strikes 
> me as adding measurable and fairly significant loss to an otherwise really 
> good, quiet antenna system, but if it lets me operate without having to worry 
> about hard faults all the time then I'll take that as a tradeoff.
> 
> - pjd
> 
> -Original Message-
> From: Jack Brindle 
> Sent: Monday, June 1, 2020 6:09 PM
> To: Peter Dougherty 
> Cc: Bob McGraw K4TAX ; elecraft@mailman.qth.net
> Subject: Re: [Elecraft] NOT the feedline
> 
> Lets take another try at this. There still isn’t enough information in your 
> emails to really determine what might be going on. From the amplifier’s 
> viewpoint, *everything* from the antenna jack on the back of the amplifier is 
> part of the antenna system. So far we know it consists of some section of 
> RG213, another of LM400, a balun of some sort, and an antenna. There are 
> undoubtedly some adapters and couplers in between, and perhaps a few other 
> things. Knowing exactly what these are is critical in making any suggestions.
> 
> Every few months since we released the KPA500 we have seen emails from folks 
> who are certain that the amplifier is causing a problem. We all build our 
> stations for low power, then decide that adding an amplifier is needed, so we 
> buy one. We then are faced with issues driving a lot more power into the 
> antenna system. These are caused by deficiencies in that system, which was 
> sized for much lower power, and almost always will contain at least one 
> component that cannot handle the power. The last part of the KPA500 before 
> power goes out is the directional coupler (note: it is after the low pass 
> filters), the KPA1500 has its ATU after those components. With the KPA1500 
> ATU in bypass, the directional coupler becomes the last component. This is 
> important because the directional coupler will see any problem in the antenna 
> system, and report it. No amplifier component is in the way to modify things, 
> we get a true picture of what follows the amplifier. So, when something 
> glitches in the antenna system (usually an arc in a coupler, or an overheated 
> toroid in a balun or matching unit), the directional coupler picks it up and 
> moves to protect the amplifier.
> 
> With this in mind, place the KPA1500 ATU into bypass and perform the test. 
> When you see the fault occur, you then need to look at the entire antenna 
> system, starting at the antenna jack on the back o

Re: [Elecraft] NOT the feedline

[Peter Dougherty]

I have an HF-Auto that is just unsuitable for contest/DX duty, even with the 
kludge workaround software--which often doesn't work right. I gave up on it and 
hope to sell it to a ragchewer who will undoubtedly make better use of it than 
I ever could. 

And I agree about the Palstar support being...unpleasant. I saved up for 3 
years to buy that and I feel sick about it. I would like to find a good 
high-quality tuner that is reliable and able to comfortably handle 1500W and 
(preferably) tune automatically via CAT control.

 - pjd

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Adrian
Sent: Monday, June 1, 2020 11:32 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline

My recent experience with Palstar has not been good. An expensive DL1500 dummy 
load in which the SO239 had not been mounted correct bwith the locknut still 
ten turns loose,

requiring dismantle and repair new out of the box by myself. Also a new 
expensive AT2K tuner in which the roller inductor shaft had not been graphite 
greased nor tensioned.

My SPE amp @ 400w went out on alarm quickly until I disassembled and repaired 
myself. I found Palstar support rude and in self denial of the issues I raised.

In hindsight I should have saved a heap of money and gone with MFJ.


On 2/6/20 1:08 pm, Jim Brown wrote:
> On 6/1/2020 5:47 PM, Peter Dougherty wrote:
>>   Ten-Tec Tuner,
>
> This might be it, Peter. ! I've used (and loved) the Ten Tec 229 and
> 238 tuners, but some of their fixed capacitors are under-rated for 
> power. This is fairly well known among Ten Tec users, so I read about 
> it somewhere and replaced those in my tuners with caps having higher 
> power ratings.
>
> There's another design flaw -- their antenna selection switch fails to 
> to provide a return for RF current, using the chassis instead. This 
> adds inductance in series with the signal path, which increasingly 
> degrades SWR and crosstalk with increasing frequency. Palstar makes 
> the same mistake in tuners I saw at Dayton 8-10 years ago. When I 
> pointed it out to a guy in their booth who claimed to be its designer, 
> he told me I was crazy!
>
> 73, Jim K9YC
>
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Re: [Elecraft] NOT the feedline

[Vic Rosenthal]

Pardon me if this has already been covered, but do you have the same problem if 
you connect the antenna to ANT-2 on the KPA? I know you don’t want to do this 
permanently, but just as a test.

Victor 4X6GP 

> On 2 Jun 2020, at 3:47, Peter Dougherty  wrote:
> 
> Thanks for the reply, Jack. 
> 
> Here's a FULL summary of what is in the line at this moment from the jack on 
> up.
> 
> PL-259 (soldered, Amphenol 83-1SP as all are) to about 2 feet of RG-213 
> feeding into a Ten-Tec Tuner, which is being used only as an antenna switch 
> and is in bypass. This is needed because the power supply fan noise on the 
> KPA-1500 is just so overwhelming that I can only power it on when needed. I 
> am primarily an HF operator, so ANT-1 is reserved for my HF stack. If I put 
> the 6m antenna on ANT-2, I would need to keep the amp running. So everything 
> goes out on ANT-1, through the TT-238. From there, one feedline goes to the 
> HF stack and the other to the 6m output. It gets SLIGHTLY better if I go 
> directly from the KPA-1500 to the input box, as follows but I still 
> experience faults.
> 
> From there, a PL-259, and 7 or 8 feet of RG-213. Another PL-259, an Amphenol 
> barrel connector in the input box, PL259, then approximately 65 or 70 feet of 
> Commscope-branded LMR-400. PL-259 from that is connected to an Amphenol 
> SO-239 female-to-N-Male, the choke balun, then the driven loop element to the 
> antenna.
> 
> As of Tuesday morning this will change as follows. KPA-1500 ANT-1 out, PL-259 
> and about 40' of Davis BuryFlex out to the remote antenna switch at the base 
> of the HF stack. From there, about 25 more feet of BuryFlex, a barrel 
> connector then the LMR-400 up to the 6m antenna. This will basically just be 
> an experiment to see if there's any improvement; I'll be bypassing both the 
> old Ten-Tec tuner/switch and the inlet box, and routing via the HF signal 
> path and automatic antenna switch. Adding 65' of BuryFlex to the path strikes 
> me as adding measurable and fairly significant loss to an otherwise really 
> good, quiet antenna system, but if it lets me operate without having to worry 
> about hard faults all the time then I'll take that as a tradeoff.
> 
> - pjd
> 
> -Original Message-
> From: Jack Brindle  
> Sent: Monday, June 1, 2020 6:09 PM
> To: Peter Dougherty 
> Cc: Bob McGraw K4TAX ; elecraft@mailman.qth.net
> Subject: Re: [Elecraft] NOT the feedline
> 
> Lets take another try at this. There still isn’t enough information in your 
> emails to really determine what might be going on. From the amplifier’s 
> viewpoint, *everything* from the antenna jack on the back of the amplifier is 
> part of the antenna system. So far we know it consists of some section of 
> RG213, another of LM400, a balun of some sort, and an antenna. There are 
> undoubtedly some adapters and couplers in between, and perhaps a few other 
> things. Knowing exactly what these are is critical in making any suggestions.
> 
> Every few months since we released the KPA500 we have seen emails from folks 
> who are certain that the amplifier is causing a problem. We all build our 
> stations for low power, then decide that adding an amplifier is needed, so we 
> buy one. We then are faced with issues driving a lot more power into the 
> antenna system. These are caused by deficiencies in that system, which was 
> sized for much lower power, and almost always will contain at least one 
> component that cannot handle the power. The last part of the KPA500 before 
> power goes out is the directional coupler (note: it is after the low pass 
> filters), the KPA1500 has its ATU after those components. With the KPA1500 
> ATU in bypass, the directional coupler becomes the last component. This is 
> important because the directional coupler will see any problem in the antenna 
> system, and report it. No amplifier component is in the way to modify things, 
> we get a true picture of what follows the amplifier. So, when something 
> glitches in the antenna system (usually an arc in a coupler, or an overheated 
> toroid in a balun or matching unit), the directional coupler picks it up and 
> moves to protect the amplifier.
> 
> With this in mind, place the KPA1500 ATU into bypass and perform the test. 
> When you see the fault occur, you then need to look at the entire antenna 
> system, starting at the antenna jack on the back of the KPA1500. All of the 
> components are suspect, even a new part (balun, antenna, etc), which may have 
> been affected by high power right after installation. Be sure to looks at the 
> RG213, and at the coupler to the LM400. You have made reference to shack 
> feed-through, what is that, and does it use components that might have issues?
> 
> As in 

Re: [Elecraft] NOT the feedline

[Bob McGraw K4TAX]

Plus there is L1 which is 0.3uH in the circuit and C7 and C8 in the 
circuit when in the bypass position.  This does not allow the tuner, 
even in bypass mode, to work well as an antenna switch on 6M.


 The capacitors in question are not rated for the RF current 
experienced under certain load Z conditions.  They heat, change value, 
and the SWR creeps up.  Allow them to cool and the SWR is back to the 
starting point.    I usually tweaked mine such that the SWR started off 
a bit high, came down as I transmitted and if transmitting a bit longer 
the SWR increased.   Later I got tired of this and changed the group of 
disk ceramic caps to 470 pf Russian doorknob caps.  Problem solved.


73

Bob, K4TAX


On 6/1/2020 10:08 PM, Jim Brown wrote:
his might be it, Peter. ! I've used (and loved) the Ten Tec 229 and 
238 tuners, but some of their fixed capacitors are under-rated for 
power. This is fairly well known among Ten Tec users, so I read about 
it somewhere and replaced those in my tuners with caps having higher 
power ratings. 


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Re: [Elecraft] NOT the feedline

[Adrian]

My recent experience with Palstar has not been good. An expensive DL1500 
dummy load in which the SO239 had not been mounted correct bwith the 
locknut still ten turns loose,


requiring dismantle and repair new out of the box by myself. Also a new 
expensive AT2K tuner in which the roller inductor shaft had not been 
graphite greased nor tensioned.


My SPE amp @ 400w went out on alarm quickly until I disassembled and 
repaired myself. I found Palstar support rude and in self denial of the 
issues I raised.


In hindsight I should have saved a heap of money and gone with MFJ.


On 2/6/20 1:08 pm, Jim Brown wrote:

On 6/1/2020 5:47 PM, Peter Dougherty wrote:

  Ten-Tec Tuner,


This might be it, Peter. ! I've used (and loved) the Ten Tec 229 and 
238 tuners, but some of their fixed capacitors are under-rated for 
power. This is fairly well known among Ten Tec users, so I read about 
it somewhere and replaced those in my tuners with caps having higher 
power ratings.


There's another design flaw -- their antenna selection switch fails to 
to provide a return for RF current, using the chassis instead. This 
adds inductance in series with the signal path, which increasingly 
degrades SWR and crosstalk with increasing frequency. Palstar makes 
the same mistake in tuners I saw at Dayton 8-10 years ago. When I 
pointed it out to a guy in their booth who claimed to be its designer, 
he told me I was crazy!


73, Jim K9YC


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Re: [Elecraft] NOT the feedline

[Adrian]

My experience is that the Balun-Designs 4:1 current balun works 
brilliantly on a well designed ocf antenna with decent height and 
proportions to


provide good band sync at the same impedance point, where the different 
band sine waves intersect, at the approx 1/3 total length feedpoint. 
shown in below from ;


https://archive.org/details/UnderstandingAndBuildingTheOCFDipole



 However these days I use delta loops, beams and verticals.

Adrian Fewster


On 2/6/20 1:01 pm, Bob McGraw K4TAX wrote:

I agree with Jim, K9YC  on these points.

** OCFD antennas are noted to have lots of common mode current 
issues.   These are a chore to tame.


** Most commercial baluns or common mode chokes are poor designs, of 
inadequate material, designs copied from other poor designs but packed 
in a pretty box of different color, size, and shape with a high price.


One of the best applications for a 4:1 balun is with a single band 
folded dipole made of equal wire diameter or size. Depending on height 
above ground the feed point Z is between 200 and 300 ohms. The use of 
a 4:1 give an impedance of 50 to 75 ohms.    Any other usage of a 4:1 
balun is more of a compromise to a disaster.


73

Bob, K4TAX


On 6/1/2020 9:41 PM, Jim Brown wrote:

On 6/1/2020 6:45 AM, Alan - G4GNX wrote:
I have a similar issue with ferrite 'balun' heating, although mostly 
tested on 40 metres. I'm using an OSCFD (Windom) which has a main 
4:1 balun at the feed point, but also has a sleeve 'balun' 
consisting of 8 ferrites wrapped in a plastic sleeve, about 3 feet 
from the feed point. If I run the K3S at 100W, via the KPA500 in 
standby, then through the KAT500 tuner, I see no problems.


On increasing the power to 200W by using the KPA500 in Operate and 
about 10W drive from the K3S, during a SSB 'over' the temperature of 
the KPA500 rises and after a few minutes, the SWR readings on the 
KPA500 and KAT500 start to rise.


Alan,

What you describe basically a lousy common mode choke, applied to an 
antenna that, because it is so badly unbalanced, has a LOT common 
mode current. The primary function of such a choke is to prevent 
common mode noise picked up on that feedline from coupling to the 
antenna, and from there to the receiver. I don't know of a way to 
EFFECTIVELY choke such an antenna. The application of ANY choke to 
such an antenna is an unnatural act -- it does nothing useful.


I strongly suggest that you study the material on my website about 
how common mode chokes work. These concepts have been part of the 
ARRL Handbook and/or Antenna Book for nearly 10 years.


k9yc.com/publish.htm

The word "balun" is used to describe nearly a dozen very different 
things. What COULD work is a two winding transformer wound on a low 
loss ferrite toroid, like Fair-Rite #61 or #67 material. #61 will 
likely handle 100W from 160M to 10M without overheating. #67, which 
has much lower loss above about 17M, may be required at the 400W 
level, and would certainly be used at 1 kW and above.


Making the windings bifilar provides a capacitive path for common 
mode current, degrading its effectiveness. This is minimized by 
placing the windings on opposite sides of the toroidal core.


73, Jim K9YC
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Re: [Elecraft] NOT the feedline

[Jim Brown]

On 6/1/2020 5:47 PM, Peter Dougherty wrote:

  Ten-Tec Tuner,


This might be it, Peter. ! I've used (and loved) the Ten Tec 229 and 238 
tuners, but some of their fixed capacitors are under-rated for power. 
This is fairly well known among Ten Tec users, so I read about it 
somewhere and replaced those in my tuners with caps having higher power 
ratings.


There's another design flaw -- their antenna selection switch fails to 
to provide a return for RF current, using the chassis instead. This adds 
inductance in series with the signal path, which increasingly degrades 
SWR and crosstalk with increasing frequency. Palstar makes the same 
mistake in tuners I saw at Dayton 8-10 years ago. When I pointed it out 
to a guy in their booth who claimed to be its designer, he told me I was 
crazy!


73, Jim K9YC
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Re: [Elecraft] NOT the feedline

[Bob McGraw K4TAX]

I agree with Jim, K9YC  on these points.

** OCFD antennas are noted to have lots of common mode current issues.   
These are a chore to tame.


** Most commercial baluns or common mode chokes are poor designs, of 
inadequate material, designs copied from other poor designs but packed 
in a pretty box of different color, size, and shape with a high price.


One of the best applications for a 4:1 balun is with a single band 
folded dipole made of equal wire diameter or size. Depending on height 
above ground the feed point Z is between 200 and 300 ohms.  The use of a 
4:1 give an impedance of 50 to 75 ohms.    Any other usage of a 4:1 
balun is more of a compromise to a disaster.


73

Bob, K4TAX


On 6/1/2020 9:41 PM, Jim Brown wrote:

On 6/1/2020 6:45 AM, Alan - G4GNX wrote:
I have a similar issue with ferrite 'balun' heating, although mostly 
tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
balun at the feed point, but also has a sleeve 'balun' consisting of 
8 ferrites wrapped in a plastic sleeve, about 3 feet from the feed 
point. If I run the K3S at 100W, via the KPA500 in standby, then 
through the KAT500 tuner, I see no problems.


On increasing the power to 200W by using the KPA500 in Operate and 
about 10W drive from the K3S, during a SSB 'over' the temperature of 
the KPA500 rises and after a few minutes, the SWR readings on the 
KPA500 and KAT500 start to rise.


Alan,

What you describe basically a lousy common mode choke, applied to an 
antenna that, because it is so badly unbalanced, has a LOT common mode 
current. The primary function of such a choke is to prevent common 
mode noise picked up on that feedline from coupling to the antenna, 
and from there to the receiver. I don't know of a way to EFFECTIVELY 
choke such an antenna. The application of ANY choke to such an antenna 
is an unnatural act -- it does nothing useful.


I strongly suggest that you study the material on my website about how 
common mode chokes work. These concepts have been part of the ARRL 
Handbook and/or Antenna Book for nearly 10 years.


k9yc.com/publish.htm

The word "balun" is used to describe nearly a dozen very different 
things. What COULD work is a two winding transformer wound on a low 
loss ferrite toroid, like Fair-Rite #61 or #67 material. #61 will 
likely handle 100W from 160M to 10M without overheating. #67, which 
has much lower loss above about 17M, may be required at the 400W 
level, and would certainly be used at 1 kW and above.


Making the windings bifilar provides a capacitive path for common mode 
current, degrading its effectiveness. This is minimized by placing the 
windings on opposite sides of the toroidal core.


73, Jim K9YC
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Re: [Elecraft] NOT the feedline

[Jim Brown]

On 6/1/2020 3:31 PM, Walter Underwood wrote:

Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating for a UHF 
connector.


The vast majority of HF stations with big power amps use UHF connectors 
throughout, and are without such problems as long as quality connectors 
are properly installed. The only problems I've ever had with connectors 
were the result the connectors being junk quality, and it hasn't been 
voltage breakdown. Rather I've had them fall apart, and I've had the 
center conductor melt.


73, Jim K9YC
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Re: [Elecraft] NOT the feedline

[Jim Brown]

On 6/1/2020 7:13 AM, Adrian wrote:
If you use a decent combination balun such as ; 
https://www.balundesigns.com/model-4116-4-1-hybrid-balun-1-5-54mhz-3kw/ 
if you have any metal structure in range of the field, or


These are probably effective as impedance matching devices, but 
everything I've seen from this company indicates they don't have a clue 
about how common mode chokes work. Several years ago, a member of our 
contest club building a big contest station in the Caribbean gave me one 
of their common mode choke "baluns" to measure. It looked NOTHING like 
the the curves published on their website, and was a LOUSY choke. It 
probably would not have blown up with power, but it certainly wouldn't 
have done much to kill common mode noise over the frequency range 
advertised.


> The true windom uses the vertical section of its feedline as part of
> the antenna, such that any ocf dipole with a feedpoint common mode
> choke cannot be referred to as a 'windom'

Whatever it's called, while it was probably a very good idea many years 
ago when it was conceived, it's a LOUSY idea today because the design is 
a sitting duck for the increasingly massive levels of RF noise in our 
homes and the homes of our neighbors. As old-timers learned many years 
ago, "if you can't hear 'em, you can't work 'em."


73, Jim K9YC
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Re: [Elecraft] NOT the feedline

[Peter Dougherty]

It's the 6 element LFA on a 6.8 meter boom. The balun is their 50 MHz ferrite 
core balun. 

I want to get the Ten-Tec tuner out of the equation forthwith but unless I can 
solve the fan noise problems it's a non-starter. My XYL is working from home in 
the same home-office that my shack is located in, about 6 feet away from my 
operating desk. The fan noise drives *me* crazy but she won't tolerate it being 
on all day when I'm just monitoring six. I work enough stuff on CW on HF for it 
to remain the primary concern, so I can't really put that on ANT-2, which I did 
try.

Hopefully going through the main antenna switch will help--I'll find out 
tomorrow. 

 - pjd

-Original Message-
From: Jack Brindle  
Sent: Monday, June 1, 2020 9:29 PM
To: Peter Dougherty 
Cc: Elecraft Mailer 
Subject: Re: [Elecraft] NOT the feedline

Is it the 3 element 6m LFA? That is an interesting antenna. Which of the baluns 
did you get? They show three - two for 50 - 70 MHz, and a third for HF and 6m. 
G0KSC has some interesting designed - I will be waiting to hear your results 
with this one.

I’ll go through your details here and see what I might come up with. In the 
mean time I will be interested in the results of your tests tomorrow. Getting 
info about the TenTec ATU/switch may be difficult, but it wouldn’t surprise me 
if that is the source. I am sure somewhere in here you will find the problem.

I usually take these problem-solving discussion off-line, but let’s leave this 
one here because of the already wide interest.

73 and have a great evening!
Jack, W6FB



> On Jun 1, 2020, at 5:47 PM, Peter Dougherty  wrote:
> 
> Thanks for the reply, Jack. 
> 
> Here's a FULL summary of what is in the line at this moment from the jack on 
> up.
> 
> PL-259 (soldered, Amphenol 83-1SP as all are) to about 2 feet of RG-213 
> feeding into a Ten-Tec Tuner, which is being used only as an antenna switch 
> and is in bypass. This is needed because the power supply fan noise on the 
> KPA-1500 is just so overwhelming that I can only power it on when needed. I 
> am primarily an HF operator, so ANT-1 is reserved for my HF stack. If I put 
> the 6m antenna on ANT-2, I would need to keep the amp running. So everything 
> goes out on ANT-1, through the TT-238. From there, one feedline goes to the 
> HF stack and the other to the 6m output. It gets SLIGHTLY better if I go 
> directly from the KPA-1500 to the input box, as follows but I still 
> experience faults.
> 
> From there, a PL-259, and 7 or 8 feet of RG-213. Another PL-259, an Amphenol 
> barrel connector in the input box, PL259, then approximately 65 or 70 feet of 
> Commscope-branded LMR-400. PL-259 from that is connected to an Amphenol 
> SO-239 female-to-N-Male, the choke balun, then the driven loop element to the 
> antenna.
> 
> As of Tuesday morning this will change as follows. KPA-1500 ANT-1 out, PL-259 
> and about 40' of Davis BuryFlex out to the remote antenna switch at the base 
> of the HF stack. From there, about 25 more feet of BuryFlex, a barrel 
> connector then the LMR-400 up to the 6m antenna. This will basically just be 
> an experiment to see if there's any improvement; I'll be bypassing both the 
> old Ten-Tec tuner/switch and the inlet box, and routing via the HF signal 
> path and automatic antenna switch. Adding 65' of BuryFlex to the path strikes 
> me as adding measurable and fairly significant loss to an otherwise really 
> good, quiet antenna system, but if it lets me operate without having to worry 
> about hard faults all the time then I'll take that as a tradeoff.
> 
> - pjd
> 
> -Original Message-
> From: Jack Brindle 
> Sent: Monday, June 1, 2020 6:09 PM
> To: Peter Dougherty 
> Cc: Bob McGraw K4TAX ; elecraft@mailman.qth.net
> Subject: Re: [Elecraft] NOT the feedline
> 
> Lets take another try at this. There still isn’t enough information in your 
> emails to really determine what might be going on. From the amplifier’s 
> viewpoint, *everything* from the antenna jack on the back of the amplifier is 
> part of the antenna system. So far we know it consists of some section of 
> RG213, another of LM400, a balun of some sort, and an antenna. There are 
> undoubtedly some adapters and couplers in between, and perhaps a few other 
> things. Knowing exactly what these are is critical in making any suggestions.
> 
> Every few months since we released the KPA500 we have seen emails from folks 
> who are certain that the amplifier is causing a problem. We all build our 
> stations for low power, then decide that adding an amplifier is needed, so we 
> buy one. We then are faced with issues driving a lot more power into the 
> antenna system. These are caused by deficiencies in that system, which was 
> sized for much lower power, and almost always will contain at l

Re: [Elecraft] NOT the feedline

[Jim Brown]

On 6/1/2020 6:45 AM, Alan - G4GNX wrote:
I have a similar issue with ferrite 'balun' heating, although mostly 
tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
balun at the feed point, but also has a sleeve 'balun' consisting of 8 
ferrites wrapped in a plastic sleeve, about 3 feet from the feed point. 
If I run the K3S at 100W, via the KPA500 in standby, then through the 
KAT500 tuner, I see no problems.


On increasing the power to 200W by using the KPA500 in Operate and about 
10W drive from the K3S, during a SSB 'over' the temperature of the 
KPA500 rises and after a few minutes, the SWR readings on the KPA500 and 
KAT500 start to rise.


Alan,

What you describe basically a lousy common mode choke, applied to an 
antenna that, because it is so badly unbalanced, has a LOT common mode 
current. The primary function of such a choke is to prevent common mode 
noise picked up on that feedline from coupling to the antenna, and from 
there to the receiver. I don't know of a way to EFFECTIVELY choke such 
an antenna. The application of ANY choke to such an antenna is an 
unnatural act -- it does nothing useful.


I strongly suggest that you study the material on my website about how 
common mode chokes work. These concepts have been part of the ARRL 
Handbook and/or Antenna Book for nearly 10 years.


k9yc.com/publish.htm

The word "balun" is used to describe nearly a dozen very different 
things. What COULD work is a two winding transformer wound on a low loss 
ferrite toroid, like Fair-Rite #61 or #67 material. #61 will likely 
handle 100W from 160M to 10M without overheating. #67, which has much 
lower loss above about 17M, may be required at the 400W level, and would 
certainly be used at 1 kW and above.


Making the windings bifilar provides a capacitive path for common mode 
current, degrading its effectiveness. This is minimized by placing the 
windings on opposite sides of the toroidal core.


73, Jim K9YC
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Re: [Elecraft] NOT the feedline

[Jack Brindle via Elecraft]

Is it the 3 element 6m LFA? That is an interesting antenna. Which of the baluns 
did you get? They show three - two for 50 - 70 MHz, and a third for HF and 6m. 
G0KSC has some interesting designed - I will be waiting to hear your results 
with this one.

I’ll go through your details here and see what I might come up with. In the 
mean time I will be interested in the results of your tests tomorrow. Getting 
info about the TenTec ATU/switch may be difficult, but it wouldn’t surprise me 
if that is the source. I am sure somewhere in here you will find the problem.

I usually take these problem-solving discussion off-line, but let’s leave this 
one here because of the already wide interest.

73 and have a great evening!
Jack, W6FB



> On Jun 1, 2020, at 5:47 PM, Peter Dougherty  wrote:
> 
> Thanks for the reply, Jack. 
> 
> Here's a FULL summary of what is in the line at this moment from the jack on 
> up.
> 
> PL-259 (soldered, Amphenol 83-1SP as all are) to about 2 feet of RG-213 
> feeding into a Ten-Tec Tuner, which is being used only as an antenna switch 
> and is in bypass. This is needed because the power supply fan noise on the 
> KPA-1500 is just so overwhelming that I can only power it on when needed. I 
> am primarily an HF operator, so ANT-1 is reserved for my HF stack. If I put 
> the 6m antenna on ANT-2, I would need to keep the amp running. So everything 
> goes out on ANT-1, through the TT-238. From there, one feedline goes to the 
> HF stack and the other to the 6m output. It gets SLIGHTLY better if I go 
> directly from the KPA-1500 to the input box, as follows but I still 
> experience faults.
> 
> From there, a PL-259, and 7 or 8 feet of RG-213. Another PL-259, an Amphenol 
> barrel connector in the input box, PL259, then approximately 65 or 70 feet of 
> Commscope-branded LMR-400. PL-259 from that is connected to an Amphenol 
> SO-239 female-to-N-Male, the choke balun, then the driven loop element to the 
> antenna.
> 
> As of Tuesday morning this will change as follows. KPA-1500 ANT-1 out, PL-259 
> and about 40' of Davis BuryFlex out to the remote antenna switch at the base 
> of the HF stack. From there, about 25 more feet of BuryFlex, a barrel 
> connector then the LMR-400 up to the 6m antenna. This will basically just be 
> an experiment to see if there's any improvement; I'll be bypassing both the 
> old Ten-Tec tuner/switch and the inlet box, and routing via the HF signal 
> path and automatic antenna switch. Adding 65' of BuryFlex to the path strikes 
> me as adding measurable and fairly significant loss to an otherwise really 
> good, quiet antenna system, but if it lets me operate without having to worry 
> about hard faults all the time then I'll take that as a tradeoff.
> 
> - pjd
> 
> -Original Message-
> From: Jack Brindle  
> Sent: Monday, June 1, 2020 6:09 PM
> To: Peter Dougherty 
> Cc: Bob McGraw K4TAX ; elecraft@mailman.qth.net
> Subject: Re: [Elecraft] NOT the feedline
> 
> Lets take another try at this. There still isn’t enough information in your 
> emails to really determine what might be going on. From the amplifier’s 
> viewpoint, *everything* from the antenna jack on the back of the amplifier is 
> part of the antenna system. So far we know it consists of some section of 
> RG213, another of LM400, a balun of some sort, and an antenna. There are 
> undoubtedly some adapters and couplers in between, and perhaps a few other 
> things. Knowing exactly what these are is critical in making any suggestions.
> 
> Every few months since we released the KPA500 we have seen emails from folks 
> who are certain that the amplifier is causing a problem. We all build our 
> stations for low power, then decide that adding an amplifier is needed, so we 
> buy one. We then are faced with issues driving a lot more power into the 
> antenna system. These are caused by deficiencies in that system, which was 
> sized for much lower power, and almost always will contain at least one 
> component that cannot handle the power. The last part of the KPA500 before 
> power goes out is the directional coupler (note: it is after the low pass 
> filters), the KPA1500 has its ATU after those components. With the KPA1500 
> ATU in bypass, the directional coupler becomes the last component. This is 
> important because the directional coupler will see any problem in the antenna 
> system, and report it. No amplifier component is in the way to modify things, 
> we get a true picture of what follows the amplifier. So, when something 
> glitches in the antenna system (usually an arc in a coupler, or an overheated 
> toroid in a balun or matching unit), the directional coupler picks it up and 
> moves to protect the amplifier.
> 
> With this in mind, place the KPA1500 ATU into bypass

Re: [Elecraft] NOT the feedline

[Peter Dougherty]

Thanks for the reply, Jack. 

Here's a FULL summary of what is in the line at this moment from the jack on up.

PL-259 (soldered, Amphenol 83-1SP as all are) to about 2 feet of RG-213 feeding 
into a Ten-Tec Tuner, which is being used only as an antenna switch and is in 
bypass. This is needed because the power supply fan noise on the KPA-1500 is 
just so overwhelming that I can only power it on when needed. I am primarily an 
HF operator, so ANT-1 is reserved for my HF stack. If I put the 6m antenna on 
ANT-2, I would need to keep the amp running. So everything goes out on ANT-1, 
through the TT-238. From there, one feedline goes to the HF stack and the other 
to the 6m output. It gets SLIGHTLY better if I go directly from the KPA-1500 to 
the input box, as follows but I still experience faults.

From there, a PL-259, and 7 or 8 feet of RG-213. Another PL-259, an Amphenol 
barrel connector in the input box, PL259, then approximately 65 or 70 feet of 
Commscope-branded LMR-400. PL-259 from that is connected to an Amphenol SO-239 
female-to-N-Male, the choke balun, then the driven loop element to the antenna.

As of Tuesday morning this will change as follows. KPA-1500 ANT-1 out, PL-259 
and about 40' of Davis BuryFlex out to the remote antenna switch at the base of 
the HF stack. From there, about 25 more feet of BuryFlex, a barrel connector 
then the LMR-400 up to the 6m antenna. This will basically just be an 
experiment to see if there's any improvement; I'll be bypassing both the old 
Ten-Tec tuner/switch and the inlet box, and routing via the HF signal path and 
automatic antenna switch. Adding 65' of BuryFlex to the path strikes me as 
adding measurable and fairly significant loss to an otherwise really good, 
quiet antenna system, but if it lets me operate without having to worry about 
hard faults all the time then I'll take that as a tradeoff.

 - pjd

-Original Message-
From: Jack Brindle  
Sent: Monday, June 1, 2020 6:09 PM
To: Peter Dougherty 
Cc: Bob McGraw K4TAX ; elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline

Lets take another try at this. There still isn’t enough information in your 
emails to really determine what might be going on. From the amplifier’s 
viewpoint, *everything* from the antenna jack on the back of the amplifier is 
part of the antenna system. So far we know it consists of some section of 
RG213, another of LM400, a balun of some sort, and an antenna. There are 
undoubtedly some adapters and couplers in between, and perhaps a few other 
things. Knowing exactly what these are is critical in making any suggestions.

Every few months since we released the KPA500 we have seen emails from folks 
who are certain that the amplifier is causing a problem. We all build our 
stations for low power, then decide that adding an amplifier is needed, so we 
buy one. We then are faced with issues driving a lot more power into the 
antenna system. These are caused by deficiencies in that system, which was 
sized for much lower power, and almost always will contain at least one 
component that cannot handle the power. The last part of the KPA500 before 
power goes out is the directional coupler (note: it is after the low pass 
filters), the KPA1500 has its ATU after those components. With the KPA1500 ATU 
in bypass, the directional coupler becomes the last component. This is 
important because the directional coupler will see any problem in the antenna 
system, and report it. No amplifier component is in the way to modify things, 
we get a true picture of what follows the amplifier. So, when something 
glitches in the antenna system (usually an arc in a coupler, or an overheated 
toroid in a balun or matching unit), the directional coupler picks it up and 
moves to protect the amplifier.

With this in mind, place the KPA1500 ATU into bypass and perform the test. When 
you see the fault occur, you then need to look at the entire antenna system, 
starting at the antenna jack on the back of the KPA1500. All of the components 
are suspect, even a new part (balun, antenna, etc), which may have been 
affected by high power right after installation. Be sure to looks at the RG213, 
and at the coupler to the LM400. You have made reference to shack feed-through, 
what is that, and does it use components that might have issues?

As in past cases, find the problem in the overall antenna system, and the 
KPA1500 will be much happier, as will you.

So, before we can help you, we need to know the details of the system.

73!
Jack, W6FB
Elecraft Engineering


> On Jun 1, 2020, at 2:25 PM, Peter Dougherty  wrote:
> 
> Your point is valid, however the underlying fact in my situation is that the 
> new antenna with the new 1:1 current balun (i.e. feedline choke) is 
> presenting **identically** to my old antenna that didn't have a balun. 
> Neither better nor worse.
> 
> - pjd
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net 

Re: [Elecraft] NOT the feedline

[Ted Edwards W3TB]

Back to Bob K4TAX
I had a common mode current problem when I lived in Virginia and ran 100
watts barefoot, and it came as I could not do a significant angle away from
the antenna --- which I eventually solved.

I really do love the OCF idea.  Through modeling it and patterns and then
careful selection of trees for directionality, I have been able to land the
lobes on Europe, South America, and East Asia for 40m, 20m, and 15m with
upwards of 8 dBi --- not too shabby for a wire antenna.

I have some LMR-400 and RG-9 B/U here and plan to change out the coax.  I
no longer expect that work to solve the issue, so I am looking at baluns.
While it is a change back from a current balun to voltage balun, I must may
do it.

Thanks for all the good wisdom, guys!

On Mon, Jun 1, 2020 at 6:33 PM David Gilbert  wrote:

> I had an antenna for 160m that had a fairly high SWR at the feedpoint, but
> was easy to match to 50 ohms with a series inductor less than 30 feet
> further down the line toward the shack.  I put a common mode choke per
> K9YC's designs at the antenna feedpoint, though, and even though it was
> actually two chokes in series (two large cores with separate windings) that
> should easily handle 5 KW under matched conditions, at 1.5 KW it heated up
> in less than two seconds to put the QRO Tech HF-2500DX amp into a fault.  I
> could have moved the choke to the shack side of the matching inductor, but
> I decided it was best to just fix the antenna.  No problems after I did.
>
> Common mode chokes don't need high saturation current to get hot (and
> that's rarely the problem anyway) ... high SWR voltages work just fine for
> that.  And at high power it can happen in a very brief period of time.
>
> Everyone stay safe,
> Dave   AB7E
>
>
> >
> __
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>


-- 
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."
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Re: [Elecraft] NOT the feedline

[David Gilbert]

I had an antenna for 160m that had a fairly high SWR at the feedpoint, but
was easy to match to 50 ohms with a series inductor less than 30 feet
further down the line toward the shack.  I put a common mode choke per
K9YC's designs at the antenna feedpoint, though, and even though it was
actually two chokes in series (two large cores with separate windings) that
should easily handle 5 KW under matched conditions, at 1.5 KW it heated up
in less than two seconds to put the QRO Tech HF-2500DX amp into a fault.  I
could have moved the choke to the shack side of the matching inductor, but
I decided it was best to just fix the antenna.  No problems after I did.

Common mode chokes don't need high saturation current to get hot (and
that's rarely the problem anyway) ... high SWR voltages work just fine for
that.  And at high power it can happen in a very brief period of time.

Everyone stay safe,
Dave   AB7E


>
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Re: [Elecraft] NOT the feedline

[Dave Cole]

Is it possible that Common mode is getting into the amp, and forcing a 
fault?


73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources

On 6/1/20 2:40 PM, Fred Jensen wrote:
Nearly same experience Bob:  Sloping V, 135 ft legs, from top of 80 ft 
tower fed with homemade 600 ohm open wire using a DX Engineering 4:1 
"balun" [a strange, usually misunderstood piece of electronic apparatus 
often used for the wrong reasons] rated at 10 KW.  It warmed up 
noticeably at 1.2 KW RTTY use.  It helps to remember that one can 
saturate a ferrite core [especially when very hot] which creates a 
racket reminiscent of a non-synchronous spark gap TX.


73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:
Based on my experience, balun power ratings are for MATCHED 
conditions. It is rare that hams use a balun in a matched condition. 
   Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on the 
output, while a 4:1 balun should see 200 ohms on the output and 50 
ohms on the input.   In the case of a resonant folded dipole, a 4:1 
balun is typically operating in a nearly matched condition. All others 
combinations are unknown and random.


I run about 500 watts on all bands.  My baluns are rated at 5KW! It 
takes 3 or 4 big hunkin' pieces of ferrite to attain this power 
level.   My 6 meter balun is a 1/2 wavelength electrically of RG-213. 
No ferrite!


Buy or build a balun of your choice.  Using an IR temperature gun, 
measure the ambient temperature of the core.  Run about 1/2 rated 
power carrier for 30 to 60 seconds.  Measure the temperature again. If 
it is warm to hot, this is RF producing heat.   And likely continuing 
will produce core failure.   This is not a good balun for your 
application.


One of my baluns work between the output of my KAT500 and the balanced 
feed line connected to the center of a 256 ft wire.  That antenna 
works 160M - 6M with zero issues.   Now, I do run a hybrid balun being 
a 4:1 Guanella balun as a transformer, and it is fed with a 1:1 balun 
for common mode rejection.


Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are 
not at all a proper balun design   A Guanella balun will have 2 cores 
with 2 windings and then another 2 separate cores with another 2 
windings.  These are then wired to produce a 4:1 balun with good 
common mode rejection.    Most "factory" 4:1 baluns are poorly 
designed and built junk.


See https://www.dj0ip.de/balun-stuff/ for further references.

73

Bob, K4TAX


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Re: [Elecraft] NOT the feedline

[Walter Underwood]

Even with a 1:1 SWR, 1000 W is pretty close to the 500 V peak rating for a UHF 
connector. Type N connectors are rated at 1500 V peak.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jun 1, 2020, at 3:17 PM, George Kidder  wrote:
> 
> One of my antennas is a commercial "G5RV" fed with 33' of 450 ohm ladder 
> line, terminated in a PL-259 pair, with coax from there to the shack.  
> Apparently this combination results in very high RF voltage at the PL-259, 
> and it arcs over at 1000 W (not from an Elecraft amp!).  This combo goes wild 
> when I attempt high power on 80M, although it is stable at 100 W.  Just 
> another thing to watch out for!
> 
> 73 - George, W3HBM
> 
> On 6/1/2020 5:59 PM, Ted Edwards W3TB wrote:
>> [This message came from an external source. If suspicious, report to 
>> ab...@ilstu.edu]
>> 
>> I am following this with great interest.
>> Like Alan G0GNX, I also use an OCF, RG-8X out to the current balun in this
>> case, 300 ohm to the antenna.  K3, KPA-500 and KAT-500.
>> 
>> If I am running stations in a contest on 40m and also 80m CW, It "appears"
>> that my VSWR rises after a half hour and then the KAT-500 starts to try to
>> spontaneously retune.  Doesn't happen on 20m and up.  This past weekend in
>> CQ WPX, I reduced drive so that output was about 300 watts and it all
>> became tame.
>> 
>> I had thought that it was a heating of the RG-8X; then I changed my mind to
>> the current balun from Radiowavz that is rated for 1.5 KW.  I think it is
>> the balun just getting hot out there.  I had used a W2AU 4:1 balun with my
>> OCF, which is a voltage balun but I didn't know about that -- for upwards
>> of 40 years and with the Elecraft equipment for about 4 years since I got
>> the amp/tuner.  I just switched to a current balun last year with one that
>> I bought at Dayton.
>> 
>> I would have expected more problem with the voltage balun than with the
>> current balun.  I could change back to the W2AU if needed.
>> 
>> Interesting stuff, so I am reading along.  And my thanks to all of you.
>> 
>> On Mon, Jun 1, 2020 at 4:42 PM Fred Jensen  wrote:
>> 
>>> Nearly same experience Bob:  Sloping V, 135 ft legs, from top of 80 ft
>>> tower fed with homemade 600 ohm open wire using a DX Engineering 4:1
>>> "balun" [a strange, usually misunderstood piece of electronic apparatus
>>> often used for the wrong reasons] rated at 10 KW.  It warmed up
>>> noticeably at 1.2 KW RTTY use.  It helps to remember that one can
>>> saturate a ferrite core [especially when very hot] which creates a
>>> racket reminiscent of a non-synchronous spark gap TX.
>>> 
>>> 73,
>>> Fred ["Skip"] K6DGW
>>> Sparks NV DM09dn
>>> Washoe County
>>> 
>>> On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:
 Based on my experience, balun power ratings are for MATCHED
 conditions. It is rare that hams use a balun in a matched condition.
Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on the
 output, while a 4:1 balun should see 200 ohms on the output and 50
 ohms on the input.   In the case of a resonant folded dipole, a 4:1
 balun is typically operating in a nearly matched condition. All others
 combinations are unknown and random.
 
 I run about 500 watts on all bands.  My baluns are rated at 5KW! It
 takes 3 or 4 big hunkin' pieces of ferrite to attain this power
 level.   My 6 meter balun is a 1/2 wavelength electrically of RG-213.
 No ferrite!
 
 Buy or build a balun of your choice.  Using an IR temperature gun,
 measure the ambient temperature of the core.  Run about 1/2 rated
 power carrier for 30 to 60 seconds.  Measure the temperature again.
 If it is warm to hot, this is RF producing heat.   And likely
 continuing will produce core failure.   This is not a good balun for
 your application.
 
 One of my baluns work between the output of my KAT500 and the balanced
 feed line connected to the center of a 256 ft wire.  That antenna
 works 160M - 6M with zero issues.   Now, I do run a hybrid balun being
 a 4:1 Guanella balun as a transformer, and it is fed with a 1:1 balun
 for common mode rejection.
 
 Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are
 not at all a proper balun design   A Guanella balun will have 2 cores
 with 2 windings and then another 2 separate cores with another 2
 windings.  These are then wired to produce a 4:1 balun with good
 common mode rejection.Most "factory" 4:1 baluns are poorly
 designed and built junk.
 
 See https://www.dj0ip.de/balun-stuff/ for further references.
 
 73
 
 Bob, K4TAX
>>> __
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>> 
>>> This list hosted by: 

Re: [Elecraft] NOT the feedline

[George Kidder]

One of my antennas is a commercial "G5RV" fed with 33' of 450 ohm ladder 
line, terminated in a PL-259 pair, with coax from there to the shack.  
Apparently this combination results in very high RF voltage at the 
PL-259, and it arcs over at 1000 W (not from an Elecraft amp!).  This 
combo goes wild when I attempt high power on 80M, although it is stable 
at 100 W.  Just another thing to watch out for!


73 - George, W3HBM

On 6/1/2020 5:59 PM, Ted Edwards W3TB wrote:

[This message came from an external source. If suspicious, report to 
ab...@ilstu.edu]

I am following this with great interest.
Like Alan G0GNX, I also use an OCF, RG-8X out to the current balun in this
case, 300 ohm to the antenna.  K3, KPA-500 and KAT-500.

If I am running stations in a contest on 40m and also 80m CW, It "appears"
that my VSWR rises after a half hour and then the KAT-500 starts to try to
spontaneously retune.  Doesn't happen on 20m and up.  This past weekend in
CQ WPX, I reduced drive so that output was about 300 watts and it all
became tame.

I had thought that it was a heating of the RG-8X; then I changed my mind to
the current balun from Radiowavz that is rated for 1.5 KW.  I think it is
the balun just getting hot out there.  I had used a W2AU 4:1 balun with my
OCF, which is a voltage balun but I didn't know about that -- for upwards
of 40 years and with the Elecraft equipment for about 4 years since I got
the amp/tuner.  I just switched to a current balun last year with one that
I bought at Dayton.

I would have expected more problem with the voltage balun than with the
current balun.  I could change back to the W2AU if needed.

Interesting stuff, so I am reading along.  And my thanks to all of you.

On Mon, Jun 1, 2020 at 4:42 PM Fred Jensen  wrote:


Nearly same experience Bob:  Sloping V, 135 ft legs, from top of 80 ft
tower fed with homemade 600 ohm open wire using a DX Engineering 4:1
"balun" [a strange, usually misunderstood piece of electronic apparatus
often used for the wrong reasons] rated at 10 KW.  It warmed up
noticeably at 1.2 KW RTTY use.  It helps to remember that one can
saturate a ferrite core [especially when very hot] which creates a
racket reminiscent of a non-synchronous spark gap TX.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:

Based on my experience, balun power ratings are for MATCHED
conditions. It is rare that hams use a balun in a matched condition.
Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on the
output, while a 4:1 balun should see 200 ohms on the output and 50
ohms on the input.   In the case of a resonant folded dipole, a 4:1
balun is typically operating in a nearly matched condition. All others
combinations are unknown and random.

I run about 500 watts on all bands.  My baluns are rated at 5KW! It
takes 3 or 4 big hunkin' pieces of ferrite to attain this power
level.   My 6 meter balun is a 1/2 wavelength electrically of RG-213.
No ferrite!

Buy or build a balun of your choice.  Using an IR temperature gun,
measure the ambient temperature of the core.  Run about 1/2 rated
power carrier for 30 to 60 seconds.  Measure the temperature again.
If it is warm to hot, this is RF producing heat.   And likely
continuing will produce core failure.   This is not a good balun for
your application.

One of my baluns work between the output of my KAT500 and the balanced
feed line connected to the center of a 256 ft wire.  That antenna
works 160M - 6M with zero issues.   Now, I do run a hybrid balun being
a 4:1 Guanella balun as a transformer, and it is fed with a 1:1 balun
for common mode rejection.

Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are
not at all a proper balun design   A Guanella balun will have 2 cores
with 2 windings and then another 2 separate cores with another 2
windings.  These are then wired to produce a 4:1 balun with good
common mode rejection.Most "factory" 4:1 baluns are poorly
designed and built junk.

See https://www.dj0ip.de/balun-stuff/ for further references.

73

Bob, K4TAX

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--
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."
__
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Re: [Elecraft] NOT the feedline

[Jack Brindle via Elecraft]

Lets take another try at this. There still isn’t enough information in your 
emails to really determine what might be going on. From the amplifier’s 
viewpoint, *everything* from the antenna jack on the back of the amplifier is 
part of the antenna system. So far we know it consists of some section of 
RG213, another of LM400, a balun of some sort, and an antenna. There are 
undoubtedly some adapters and couplers in between, and perhaps a few other 
things. Knowing exactly what these are is critical in making any suggestions.

Every few months since we released the KPA500 we have seen emails from folks 
who are certain that the amplifier is causing a problem. We all build our 
stations for low power, then decide that adding an amplifier is needed, so we 
buy one. We then are faced with issues driving a lot more power into the 
antenna system. These are caused by deficiencies in that system, which was 
sized for much lower power, and almost always will contain at least one 
component that cannot handle the power. The last part of the KPA500 before 
power goes out is the directional coupler (note: it is after the low pass 
filters), the KPA1500 has its ATU after those components. With the KPA1500 ATU 
in bypass, the directional coupler becomes the last component. This is 
important because the directional coupler will see any problem in the antenna 
system, and report it. No amplifier component is in the way to modify things, 
we get a true picture of what follows the amplifier. So, when something 
glitches in the antenna system (usually an arc in a coupler, or an overheated 
toroid in a balun or matching unit), the directional coupler picks it up and 
moves to protect the amplifier.

With this in mind, place the KPA1500 ATU into bypass and perform the test. When 
you see the fault occur, you then need to look at the entire antenna system, 
starting at the antenna jack on the back of the KPA1500. All of the components 
are suspect, even a new part (balun, antenna, etc), which may have been 
affected by high power right after installation. Be sure to looks at the RG213, 
and at the coupler to the LM400. You have made reference to shack feed-through, 
what is that, and does it use components that might have issues?

As in past cases, find the problem in the overall antenna system, and the 
KPA1500 will be much happier, as will you.

So, before we can help you, we need to know the details of the system.

73!
Jack, W6FB
Elecraft Engineering


> On Jun 1, 2020, at 2:25 PM, Peter Dougherty  wrote:
> 
> Your point is valid, however the underlying fact in my situation is that the 
> new antenna with the new 1:1 current balun (i.e. feedline choke) is 
> presenting **identically** to my old antenna that didn't have a balun. 
> Neither better nor worse.
> 
> - pjd
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net  On 
> Behalf Of Bob McGraw K4TAX
> Sent: Monday, June 1, 2020 4:48 PM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] NOT the feedline
> 
> Based on my experience, balun power ratings are for MATCHED conditions. It is 
> rare that hams use a balun in a matched condition.Thus a 1:1 balun should 
> see 50 ohms on the input and 50 ohms on the output, while a
> 4:1 balun should see 200 ohms on the output and 50 ohms on the input. In the 
> case of a resonant folded dipole, a 4:1 balun is typically operating in a 
> nearly matched condition.All others combinations are unknown and random.
> 
> I run about 500 watts on all bands.  My baluns are rated at 5KW!   It takes 3 
> or 4 big hunkin' pieces of ferrite to attain this power level. My 6 meter 
> balun is a 1/2 wavelength electrically of RG-213.  No ferrite!
> 
> Buy or build a balun of your choice.  Using an IR temperature gun, measure 
> the ambient temperature of the core.  Run about 1/2 rated power carrier for 
> 30 to 60 seconds.  Measure the temperature again.   If it is warm to hot, 
> this is RF producing heat.   And likely continuing will produce core failure. 
>   This is not a good balun for your application.
> 
> One of my baluns work between the output of my KAT500 and the balanced feed 
> line connected to the center of a 256 ft wire.  That antenna works 160M - 6M 
> with zero issues.   Now, I do run a hybrid balun being a 4:1 Guanella balun 
> as a transformer, and it is fed with a 1:1 balun for common mode rejection.
> 
> Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are not at 
> all a proper balun design   A Guanella balun will have 2 cores with 2 
> windings and then another 2 separate cores with another 2 windings. These are 
> then wired to produce a 4:1 balun with good common mode rejection.Most 
> "factory" 4:1 baluns are poorly designed and built junk.
> 
> See https://www.dj0ip.de/balun-stuff/ for further references.
> 
> 73
&g

Re: [Elecraft] NOT the feedline

[Ted Edwards W3TB]

I am following this with great interest.
Like Alan G0GNX, I also use an OCF, RG-8X out to the current balun in this
case, 300 ohm to the antenna.  K3, KPA-500 and KAT-500.

If I am running stations in a contest on 40m and also 80m CW, It "appears"
that my VSWR rises after a half hour and then the KAT-500 starts to try to
spontaneously retune.  Doesn't happen on 20m and up.  This past weekend in
CQ WPX, I reduced drive so that output was about 300 watts and it all
became tame.

I had thought that it was a heating of the RG-8X; then I changed my mind to
the current balun from Radiowavz that is rated for 1.5 KW.  I think it is
the balun just getting hot out there.  I had used a W2AU 4:1 balun with my
OCF, which is a voltage balun but I didn't know about that -- for upwards
of 40 years and with the Elecraft equipment for about 4 years since I got
the amp/tuner.  I just switched to a current balun last year with one that
I bought at Dayton.

I would have expected more problem with the voltage balun than with the
current balun.  I could change back to the W2AU if needed.

Interesting stuff, so I am reading along.  And my thanks to all of you.

On Mon, Jun 1, 2020 at 4:42 PM Fred Jensen  wrote:

> Nearly same experience Bob:  Sloping V, 135 ft legs, from top of 80 ft
> tower fed with homemade 600 ohm open wire using a DX Engineering 4:1
> "balun" [a strange, usually misunderstood piece of electronic apparatus
> often used for the wrong reasons] rated at 10 KW.  It warmed up
> noticeably at 1.2 KW RTTY use.  It helps to remember that one can
> saturate a ferrite core [especially when very hot] which creates a
> racket reminiscent of a non-synchronous spark gap TX.
>
> 73,
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:
> > Based on my experience, balun power ratings are for MATCHED
> > conditions. It is rare that hams use a balun in a matched condition.
> >Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on the
> > output, while a 4:1 balun should see 200 ohms on the output and 50
> > ohms on the input.   In the case of a resonant folded dipole, a 4:1
> > balun is typically operating in a nearly matched condition. All others
> > combinations are unknown and random.
> >
> > I run about 500 watts on all bands.  My baluns are rated at 5KW! It
> > takes 3 or 4 big hunkin' pieces of ferrite to attain this power
> > level.   My 6 meter balun is a 1/2 wavelength electrically of RG-213.
> > No ferrite!
> >
> > Buy or build a balun of your choice.  Using an IR temperature gun,
> > measure the ambient temperature of the core.  Run about 1/2 rated
> > power carrier for 30 to 60 seconds.  Measure the temperature again.
> > If it is warm to hot, this is RF producing heat.   And likely
> > continuing will produce core failure.   This is not a good balun for
> > your application.
> >
> > One of my baluns work between the output of my KAT500 and the balanced
> > feed line connected to the center of a 256 ft wire.  That antenna
> > works 160M - 6M with zero issues.   Now, I do run a hybrid balun being
> > a 4:1 Guanella balun as a transformer, and it is fed with a 1:1 balun
> > for common mode rejection.
> >
> > Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are
> > not at all a proper balun design   A Guanella balun will have 2 cores
> > with 2 windings and then another 2 separate cores with another 2
> > windings.  These are then wired to produce a 4:1 balun with good
> > common mode rejection.Most "factory" 4:1 baluns are poorly
> > designed and built junk.
> >
> > See https://www.dj0ip.de/balun-stuff/ for further references.
> >
> > 73
> >
> > Bob, K4TAX
>
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to w3tb@gmail.com



-- 
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."
__
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Re: [Elecraft] NOT the feedline

[Fred Jensen]

Nearly same experience Bob:  Sloping V, 135 ft legs, from top of 80 ft 
tower fed with homemade 600 ohm open wire using a DX Engineering 4:1 
"balun" [a strange, usually misunderstood piece of electronic apparatus 
often used for the wrong reasons] rated at 10 KW.  It warmed up 
noticeably at 1.2 KW RTTY use.  It helps to remember that one can 
saturate a ferrite core [especially when very hot] which creates a 
racket reminiscent of a non-synchronous spark gap TX.


73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/1/2020 1:48 PM, Bob McGraw K4TAX wrote:
Based on my experience, balun power ratings are for MATCHED 
conditions. It is rare that hams use a balun in a matched condition. 
   Thus a 1:1 balun should see 50 ohms on the input and 50 ohms on the 
output, while a 4:1 balun should see 200 ohms on the output and 50 
ohms on the input.   In the case of a resonant folded dipole, a 4:1 
balun is typically operating in a nearly matched condition. All others 
combinations are unknown and random.


I run about 500 watts on all bands.  My baluns are rated at 5KW! It 
takes 3 or 4 big hunkin' pieces of ferrite to attain this power 
level.   My 6 meter balun is a 1/2 wavelength electrically of RG-213.  
No ferrite!


Buy or build a balun of your choice.  Using an IR temperature gun, 
measure the ambient temperature of the core.  Run about 1/2 rated 
power carrier for 30 to 60 seconds.  Measure the temperature again.   
If it is warm to hot, this is RF producing heat.   And likely 
continuing will produce core failure.   This is not a good balun for 
your application.


One of my baluns work between the output of my KAT500 and the balanced 
feed line connected to the center of a 256 ft wire.  That antenna 
works 160M - 6M with zero issues.   Now, I do run a hybrid balun being 
a 4:1 Guanella balun as a transformer, and it is fed with a 1:1 balun 
for common mode rejection.


Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are 
not at all a proper balun design   A Guanella balun will have 2 cores 
with 2 windings and then another 2 separate cores with another 2 
windings.  These are then wired to produce a 4:1 balun with good 
common mode rejection.    Most "factory" 4:1 baluns are poorly 
designed and built junk.


See https://www.dj0ip.de/balun-stuff/ for further references.

73

Bob, K4TAX


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Re: [Elecraft] NOT the feedline

[Peter Dougherty]

Your point is valid, however the underlying fact in my situation is that the 
new antenna with the new 1:1 current balun (i.e. feedline choke) is presenting 
**identically** to my old antenna that didn't have a balun. Neither better nor 
worse.

 - pjd

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Bob McGraw K4TAX
Sent: Monday, June 1, 2020 4:48 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline

Based on my experience, balun power ratings are for MATCHED conditions. It is 
rare that hams use a balun in a matched condition.Thus a 1:1 balun should 
see 50 ohms on the input and 50 ohms on the output, while a
4:1 balun should see 200 ohms on the output and 50 ohms on the input. In the 
case of a resonant folded dipole, a 4:1 balun is typically operating in a 
nearly matched condition.All others combinations are unknown and random.

I run about 500 watts on all bands.  My baluns are rated at 5KW!   It takes 3 
or 4 big hunkin' pieces of ferrite to attain this power level. My 6 meter balun 
is a 1/2 wavelength electrically of RG-213.  No ferrite!

Buy or build a balun of your choice.  Using an IR temperature gun, measure the 
ambient temperature of the core.  Run about 1/2 rated power carrier for 30 to 
60 seconds.  Measure the temperature again.   If it is warm to hot, this is RF 
producing heat.   And likely continuing will produce core failure.   This is 
not a good balun for your application.

One of my baluns work between the output of my KAT500 and the balanced feed 
line connected to the center of a 256 ft wire.  That antenna works 160M - 6M 
with zero issues.   Now, I do run a hybrid balun being a 4:1 Guanella balun as 
a transformer, and it is fed with a 1:1 balun for common mode rejection.

Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are not at all 
a proper balun design   A Guanella balun will have 2 cores with 2 windings and 
then another 2 separate cores with another 2 windings. These are then wired to 
produce a 4:1 balun with good common mode rejection.Most "factory" 4:1 
baluns are poorly designed and built junk.

See https://www.dj0ip.de/balun-stuff/ for further references.

73

Bob, K4TAX


On 6/1/2020 8:45 AM, Alan - G4GNX wrote:
> I have a similar issue with ferrite 'balun' heating, although mostly 
> tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
> balun at the feed point, but also has a sleeve 'balun' consisting of 8 
> ferrites wrapped in a plastic sleeve, about 3 feet from the feed 
> point. If I run the K3S at 100W, via the KPA500 in standby, then 
> through the KAT500 tuner, I see no problems.
>
> On increasing the power to 200W by using the KPA500 in Operate and 
> about 10W drive from the K3S, during a SSB 'over' the temperature of 
> the KPA500 rises and after a few minutes, the SWR readings on the
> KPA500 and KAT500 start to rise. One of the Elecraft guys actually 
> very kindly went through my fault log and came to the conclusion that 
> the fault is with the antenna/feeder and I agree with him. What is 
> strange is that if I leave a solid carrier running at 200W, I can't 
> easily reproduce the issue and I wonder if its something being 
> affected by peak excursions with SSB?
>
> When things do start to go wrong, I can usually perform a manual tune 
> with the KAT500 and the fault will then not (mostly) be apparent.
>
> Anyway, I'm in the process of replacing the entire feeder with 
> Westflex 103 and much bigger ferrites. I will also replace the main 
> balun which is a 400W device for a 1KW device, as I think that running 
> the UK max of 400W may be pushing the spec of a 400W balun. Also, the 
> balun itself or connections to it may be faulty.
>
> The point now is that I have discovered some damage to the outer 
> covering of the sleeve 'balun' which may be the result of ferrites 
> overheating or may be the cause of movement of the ferrites thus 
> causing instability. Either way, heftier devices seem to be the order 
> of the day.
>
> Although the KPA500 temperature rise is somewhat expected, I feel it's 
> a bit higher over a short period than I would like and may be due to 
> reflected power.
>
> 73,
>
> Alan. G4GNX
>
>
> -- Original Message --
> From: "David Olean" 
> To: "Peter Dougherty" 
> Cc: elecraft@mailman.qth.net
> Sent: 01/06/2020 13:25:18
> Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; 
> SWR issues)
>
>> Hello Peter
>>
>> I suspect RFI as well. I do not have a KPA1500, so my advice is not 
>> worth much, but the fact that the fault only occurs when a signal is 
>> being radiated sends me a red flag.  I had a similar problem here 
>> with my SPE amplifier power output. I was measuring it on an LP-

Re: [Elecraft] NOT the feedline

[Bob McGraw K4TAX]

Based on my experience, balun power ratings are for MATCHED conditions.  
It is rare that hams use a balun in a matched condition.    Thus a 1:1 
balun should see 50 ohms on the input and 50 ohms on the output, while a 
4:1 balun should see 200 ohms on the output and 50 ohms on the input.   
In the case of a resonant folded dipole, a 4:1 balun is typically 
operating in a nearly matched condition.    All others combinations are 
unknown and random.


I run about 500 watts on all bands.  My baluns are rated at 5KW!   It 
takes 3 or 4 big hunkin' pieces of ferrite to attain this power level.   
My 6 meter balun is a 1/2 wavelength electrically of RG-213.  No ferrite!


Buy or build a balun of your choice.  Using an IR temperature gun, 
measure the ambient temperature of the core.  Run about 1/2 rated power 
carrier for 30 to 60 seconds.  Measure the temperature again.   If it is 
warm to hot, this is RF producing heat.   And likely continuing will 
produce core failure.   This is not a good balun for your application.


One of my baluns work between the output of my KAT500 and the balanced 
feed line connected to the center of a 256 ft wire.  That antenna works 
160M - 6M with zero issues.   Now, I do run a hybrid balun being a 4:1 
Guanella balun as a transformer, and it is fed with a 1:1 balun for 
common mode rejection.


Most single core, i.e. 2 or 3 cores stacked with 2 to 4 windings are not 
at all a proper balun design   A Guanella balun will have 2 cores with 2 
windings and then another 2 separate cores with another 2 windings.  
These are then wired to produce a 4:1 balun with good common mode 
rejection.    Most "factory" 4:1 baluns are poorly designed and built junk.


See https://www.dj0ip.de/balun-stuff/ for further references.

73

Bob, K4TAX


On 6/1/2020 8:45 AM, Alan - G4GNX wrote:
I have a similar issue with ferrite 'balun' heating, although mostly 
tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
balun at the feed point, but also has a sleeve 'balun' consisting of 8 
ferrites wrapped in a plastic sleeve, about 3 feet from the feed 
point. If I run the K3S at 100W, via the KPA500 in standby, then 
through the KAT500 tuner, I see no problems.


On increasing the power to 200W by using the KPA500 in Operate and 
about 10W drive from the K3S, during a SSB 'over' the temperature of 
the KPA500 rises and after a few minutes, the SWR readings on the 
KPA500 and KAT500 start to rise. One of the Elecraft guys actually 
very kindly went through my fault log and came to the conclusion that 
the fault is with the antenna/feeder and I agree with him. What is 
strange is that if I leave a solid carrier running at 200W, I can't 
easily reproduce the issue and I wonder if its something being 
affected by peak excursions with SSB?


When things do start to go wrong, I can usually perform a manual tune 
with the KAT500 and the fault will then not (mostly) be apparent.


Anyway, I'm in the process of replacing the entire feeder with 
Westflex 103 and much bigger ferrites. I will also replace the main 
balun which is a 400W device for a 1KW device, as I think that running 
the UK max of 400W may be pushing the spec of a 400W balun. Also, the 
balun itself or connections to it may be faulty.


The point now is that I have discovered some damage to the outer 
covering of the sleeve 'balun' which may be the result of ferrites 
overheating or may be the cause of movement of the ferrites thus 
causing instability. Either way, heftier devices seem to be the order 
of the day.


Although the KPA500 temperature rise is somewhat expected, I feel it's 
a bit higher over a short period than I would like and may be due to 
reflected power.


73,

Alan. G4GNX


-- Original Message --
From: "David Olean" 
To: "Peter Dougherty" 
Cc: elecraft@mailman.qth.net
Sent: 01/06/2020 13:25:18
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; 
SWR issues)



Hello Peter

I suspect RFI as well. I do not have a KPA1500, so my advice is not 
worth much, but the fact that the fault only occurs when a signal is 
being radiated sends me a red flag.  I had a similar problem here 
with my SPE amplifier power output. I was measuring it on an LP-100A 
wattmeter.  It turns out that 1.8 MHz energy from the SPE amp 
radiated from my vertical antenna and  was getting into a new wire 
doublet antenna and coming back down the ladder line into the shack. 
The ladder line was about 7 inches from the power coupler for the 
LP-100A. RF caused the readings to go wacky and it looked like my 
amplifier was going postal! The problem was high rf fields next to 
the power meter coupler.


Ferrite balun heating can be seen with a VSWR meter if you set the 
power at some intermediate level, key the amp up with a steady 
carrier, and watch for VSWR creeping up.  Loose pins in coax can also 
be a problem. They can heat up and disconnect or start arcing. Those 
problems do

Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Ned Mountain WC4X]

I had a similar issue with my K3s/KPA 1500 that defied logic.  Without going
into all the details, I finally sent both the K3s and KPA 1500 back to
Elecraft to have them analyze it as a systems problem.  It turned out to be
a faulty 100W PA on the K3s that would generate very short high level
transient pulses that somehow caused the fault.  Since having that replaced
all has been extremely stable for over 12 months.

This problem always happened on 6 meters, sometimes on 10 meters, but never
on any lower frequencies.

Best of luck.

Ned
WC4X 



--
Sent from: http://elecraft.365791.n2.nabble.com/
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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Jim Brown]

On 6/1/2020 6:37 AM, stephen shearer wrote:

Ground loops can be another issue.
I was having a "feed back" issue with my KX3/KXPA100 ans solved it 
eliminating ground/power loops.


DANGER, WILL ROBINSON!

First, ain't no such thing as a "ground loop." The real cause of 
problems we BLAME on this fictional condition is failure to do proper 
bonding within our stations and all other "grounds" in our homes.


BY LAW (Electrical Building Codes, usually a version of NEC or based on 
NEC), ALL grounds in any facility must be bonded together. At a minimum, 
all equipment plugged into the wall must have its chassis bonded to the 
green wire in its power cord.


In a ham station, every chassis must be directly bonded to the others by 
short, fat copper, AND all equipment that will be interconnected with 
the station (rig, computer, audio interface) should get AC power from 
outlets that share the same green wire back to the breaker panel.


Lots of detail on this in http://k9yc.com/GroundingAndAudio.pdf  and in 
N0AX's ARRL book on the topic, on which we collaborated.


73, Jim K9YC













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Re: [Elecraft] NOT the feedline

[Adrian]

In that case, then it should also fault with a 50 ohm dummy load under 
the same settings.


Does it ?


Adrian Fewster


Everything I'm seeing is pointing to the fault


being inside the KPA-1500 at this point.

  - pjd


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Re: [Elecraft] NOT the feedline

[Peter Dougherty]

The balun (1:1 current choke here) is a red herring. 

If you follow this thread all the way back, you'll see that the previous
antenna was not balun fed, and it used a length of 75 ohm cable and stubs to
match. And in this case the balun is made by InnovAntennas, specifically for
this antenna (also of their design in the UK). If changing any one or two
components had made a significant difference I would have noted it. 

First was the antenna change. When that failed to show a marked difference
then I replaced the feedline. Again, no change whatsoever. It's behaving the
same today as it has since I first got on 6m with high power. So either the
amp has an issue or it's something incredibly esoteric that will take a
miracle to find and fix.

I have tried going through an antenna switch and switching via the KPA-1500.
No difference. All coax connectors are genuine Amphenol 83-SP1 and assembled
correctly. New LMR-400 coax, purchased last year and stored inside over the
winter, and new(ish) RG-213 patch cable inside the house. I don't ever reuse
connectors or outdoor coax. Everything I'm seeing is pointing to the fault
being inside the KPA-1500 at this point.

 - pjd

-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Adrian
Sent: Monday, June 1, 2020 10:13 AM
To: Alan - G4GNX ; Elecraft Reflector

Subject: Re: [Elecraft] NOT the feedline

If you use a decent combination balun such as ;
https://www.balundesigns.com/model-4116-4-1-hybrid-balun-1-5-54mhz-3kw/
if you have any metal structure in range of the field, or

https://www.balundesigns.com/model-4115ocf-4-1-for-ocf-dipoles-1-5-54-mhz-5k
w/
for a total current 4:1 balun. These are very robust at high power, and no
other feedpoint RF common mode choke is required.

I ran a K3 , amp and ocf dipole like this, with above balun earlier this
decade with great success, had top 4a4a dxpedition total band vk points with
this one antenna. Also the windom and ocf are different animals.

The true windom uses the vertical section of its feedline as part of the
antenna, such that any ocf dipole with a feedpoint common mode choke cannot
be referred to as a 'windom'

Adrian Fewster


On 1/6/20 11:45 pm, Alan - G4GNX wrote:
> I have a similar issue with ferrite 'balun' heating, although mostly 
> tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
> balun at the feed point, but also has a sleeve 'balun' consisting of 8 
> ferrites wrapped in a plastic sleeve, about 3 feet from the feed 
> point. If I run the K3S at 100W, via the KPA500 in standby, then 
> through the KAT500 tuner, I see no problems.
>
> On increasing the power to 200W by using the KPA500 in Operate and 
> about 10W drive from the K3S, during a SSB 'over' the temperature of 
> the KPA500 rises and after a few minutes, the SWR readings on the
> KPA500 and KAT500 start to rise. One of the Elecraft guys actually 
> very kindly went through my fault log and came to the conclusion that 
> the fault is with the antenna/feeder and I agree with him. What is 
> strange is that if I leave a solid carrier running at 200W, I can't 
> easily reproduce the issue and I wonder if its something being 
> affected by peak excursions with SSB?
>
> When things do start to go wrong, I can usually perform a manual tune 
> with the KAT500 and the fault will then not (mostly) be apparent.
>
> Anyway, I'm in the process of replacing the entire feeder with 
> Westflex 103 and much bigger ferrites. I will also replace the main 
> balun which is a 400W device for a 1KW device, as I think that running 
> the UK max of 400W may be pushing the spec of a 400W balun. Also, the 
> balun itself or connections to it may be faulty.
>
> The point now is that I have discovered some damage to the outer 
> covering of the sleeve 'balun' which may be the result of ferrites 
> overheating or may be the cause of movement of the ferrites thus 
> causing instability. Either way, heftier devices seem to be the order 
> of the day.
>
> Although the KPA500 temperature rise is somewhat expected, I feel it's 
> a bit higher over a short period than I would like and may be due to 
> reflected power.
>
> 73,
>
> Alan. G4GNX
>
>
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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

I have never driven the amp with 90 Watts. Ever. The 90W figure is what comes 
out of the K3s *after* the amp has tripped out. With the amp in 'operate' I 
feed it typically 25-35 Watts.

Here are the error codes, as requested (truncated for length--there are MANY 
more): 
441 20-06-01T01:02:22 FLT 90 - PWR REFL  freq 50304 inp 13W fwd 1064W refl 198W 
swr 2.5 23A 32C adc 280 var 198
440 20-05-31T23:45:57 FLT 90 - PWR REFL  freq 50008 inp 22W fwd 1356W refl 199W 
swr 2.2 44A 45C adc 281 var 199
439 20-05-31T23:43:46 OVR 90 - PWR REFL  freq 50304 inp 23W fwd 1210W refl 172W 
swr 2.2 39A 31C adc 257 var 172
438 20-05-31T23:43:39 OVR 90 - PWR REFL  freq 50304 inp 23W fwd 1204W refl 172W 
swr 2.2 39A 28C adc 257 var 172
437 20-05-31T23:43:13 FLT 90 - PWR REFL  freq 50304 inp 23W fwd 1298W refl 202W 
swr 2.3 44A 27C adc 284 var 202
435 20-05-31T02:39:03 OVR 90 - PWR REFL  freq 50304 inp 14W fwd 1107W refl 178W 
swr 2.3 23A 47C adc 262 var 178
434 20-05-31T02:34:03 FLT 90 - PWR REFL  freq 50304 inp 15W fwd 1152W refl 198W 
swr 2.4 28A 33C adc 280 var 198
433 20-05-31T02:25:03 OVR 90 - PWR REFL  freq 50304 inp 15W fwd 1130W refl 187W 
swr 2.3 24A 43C adc 270 var 187
432 20-05-31T02:23:03 FLT 90 - PWR REFL  freq 50304 inp 18W fwd 1165W refl 199W 
swr 2.4 40A 43C adc 281 var 199
431 20-05-31T02:21:33 FLT 90 - PWR REFL  freq 50304 inp 20W fwd 1189W refl 201W 
swr 2.3 46A 48C adc 283 var 201
 

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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

The new full-length LMR-400 cable is about 3 feet longer than the old 2-section 
coax I had before (old = 3/8” hardline and about 8 feet of RG-213). The entry 
point is grounded to rod immediately below it, connected by 1.5” braid. 

 

- pjd

 

From: Mark Goldberg  
Sent: Monday, June 1, 2020 12:45 AM
To: Peter Dougherty 
Cc: Adrian ; Paul Baldock ; Elecraft 
Mailing List 
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR 
issues)

 

I haven't seen a discussion of your grounding system or feedline length. 6M can 
be picky.  What does your ground system look like? Do you have any common mode 
chokes on the feedline? Have you tried adding or subtracting 2-3 feet from the 
feedline? If it is exactly a multiple of 1/2 wave or 1/4 wave changing the 
feedline length will move it away from that. Have you tried adding a 
counterpoise in the shack? That's not the ultimate solution but if it improves 
things it will tell you something. Can you point an IR thermometer at tuner / 
balun inductors to see if they are getting hot? Just throwing out ideas.

 

73,

 

Mark

W7MLG

 

 

On Sun, May 31, 2020 at 9:08 PM Peter Dougherty mailto:li...@w2irt.net> > wrote:

New coax and old coax behaved identically. HOWEVER, running into about 80 feet 
of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is 
the only condition on 6m where there is no fault. Brand new coax, old coax, 
brand new antenna, old antenna, with balun, without balun. Always faults except 
when feeding the pure resistive dummy load. If there's any reactance it trips 
or gives false SWR info.

I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of 
drive? On the regular HF bands I can use the internal tuner to take out a 2.5 
or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..

 - pjd
  

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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

That's worth a shot. I have a ~7 foot RG-213 patch cable from the back of the 
amp to the entry box. I don't have any more LMR-400 so I can't use that, but I 
do have quite a bit of 213 and will make a new patch cable. That's the only bit 
of the old system that's still remaining. 
 - pjd

-Original Message-
From: Vic Rosenthal  
Sent: Monday, June 1, 2020 12:18 AM
To: Peter Dougherty 
Cc: j...@audiosystemsgroup.com; Elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR 
issues)

Are you using the same output connector on the KPA1500 for the dummy load and 
the antenna? 
Perhaps the problem is in one of the SO239s or in the KPA’s switching circuit?

Victor 4X6GP 

> On 1 Jun 2020, at 4:30, Peter Dougherty  wrote:
> 
> Many here suggested that it was most likely a feedline issue, and I 
> figured this was indeed a distinct possibility.
> 
> So this afternoon I replaced the feedline. I now have about 80 feet of 
> brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at 
> the balun since I don't have any type-N connectors here). The AA-230 
> ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below 
> the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the 
> KPA.
> 
> The TDR screen looks very clean, just a tiny bump where the feedline 
> goes through the (new) bulkhead connector to get into the house. See:
> https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl
> =0
> 
> The SWR chart between 50.000 and 50.500:
> https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl
> =0
> 
> Again, I know the antenna is resonant a bit low, but this should NOT 
> be a factor. So here's what's now going on.
> 
> 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the 
> KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering 
> power and no faults.
> 
> 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 
> into the Cantenna. Again, no problem delivering power to the purely resistive 
> load.
> Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 
> second periods without issue.
> 
> 3) When I switch over to the live antenna, with25 Watts of drive from 
> the K3s into the actual antenna and the amp faults out instantly in 
> bypass. When the amplifier is in bypass and the tuner is in bypass, 
> and when the K3s is delivering about 90W in FT8 mode, the front panel 
> on the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on 
> the radio, it's showing an SWR of 1.4:1.
> 
> 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the 
> front panel of the KPA-1500 is showing a perfect 1.0:1 match. It 
> SHOULD work fine like this, right?
> 
> 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA 
> tuner in and untouched since step 4), the amp SOMETIMES delivers 
> power, sometimes faults out, shows an SWR of 1.7:1. Pressing the 
> OPER/STBY button again to use only exciter power, and touching NOTHING 
> ELSE, it's back to 1.1:1 with 90W of K3s drive.
> 
> 6) There is basically no rhyme or reason why this is happening and 
> it's
> *somewhat* repeatable. The incredibly frustrating part is if I see a 
> needed station come up, I'll flick the amp's tuner in line and it says it's 
> tuned.
> Once WSJT-X keys the radio, 90 out of 100 times the amp will 
> hard-fault. If it doesn't fault on the first transmission, it 
> absolutely WILL on the second transmission.
> 
> So I'm now at a complete loss to understand what's going on here. Amp 
> is fine into a resistive load. Brand-new antenna, brand new LMR-400 
> feedline, brand new connectors, the KPA-1500 is faulting out the same 
> as it did on the
> 10+ year old 6M5 with a patchwork of feedlines. I can't see how this 
> 10+ is
> anything but a problem in the KPA-1500 (S/N 0398).
> 
> - pjd
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net 
>  On Behalf Of Jim Brown
> Sent: Sunday, May 31, 2020 8:22 PM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues
> 
>> On 5/31/2020 9:54 AM, Jim Miller wrote:
>> Have you vetted your feedline at 1500w? Many times something might be 
>> good at low power and fail at 1500.
> 
> This is good advice. Guys who do lots of portable setup say to always 
> check the coax first, which mostly means check for a connector that's 
> bad or badly installed.
> 
> In general, if it doesn't say Amphenol or isn't stamped with a MIL 
> spec number, it's very likely to be poor quality. This includes 
> barrels, adapters, etc.  Also make sure that every connector is" wrench 
> tight."
> 
> The adv

Re: [Elecraft] NOT the feedline

[Adrian]

If you use a decent combination balun such as ; 
https://www.balundesigns.com/model-4116-4-1-hybrid-balun-1-5-54mhz-3kw/ 
if you have any metal structure in range of the field, or


https://www.balundesigns.com/model-4115ocf-4-1-for-ocf-dipoles-1-5-54-mhz-5kw/ 
for a total current 4:1 balun. These are very robust at high power, and 
no other feedpoint RF common mode choke is required.


I ran a K3 , amp and ocf dipole like this, with above balun earlier this 
decade with great success, had top 4a4a dxpedition total band vk points 
with this one antenna. Also the windom and ocf are different animals.


The true windom uses the vertical section of its feedline as part of the 
antenna, such that any ocf dipole with a feedpoint common mode choke 
cannot be referred to as a 'windom'


Adrian Fewster


On 1/6/20 11:45 pm, Alan - G4GNX wrote:
I have a similar issue with ferrite 'balun' heating, although mostly 
tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
balun at the feed point, but also has a sleeve 'balun' consisting of 8 
ferrites wrapped in a plastic sleeve, about 3 feet from the feed 
point. If I run the K3S at 100W, via the KPA500 in standby, then 
through the KAT500 tuner, I see no problems.


On increasing the power to 200W by using the KPA500 in Operate and 
about 10W drive from the K3S, during a SSB 'over' the temperature of 
the KPA500 rises and after a few minutes, the SWR readings on the 
KPA500 and KAT500 start to rise. One of the Elecraft guys actually 
very kindly went through my fault log and came to the conclusion that 
the fault is with the antenna/feeder and I agree with him. What is 
strange is that if I leave a solid carrier running at 200W, I can't 
easily reproduce the issue and I wonder if its something being 
affected by peak excursions with SSB?


When things do start to go wrong, I can usually perform a manual tune 
with the KAT500 and the fault will then not (mostly) be apparent.


Anyway, I'm in the process of replacing the entire feeder with 
Westflex 103 and much bigger ferrites. I will also replace the main 
balun which is a 400W device for a 1KW device, as I think that running 
the UK max of 400W may be pushing the spec of a 400W balun. Also, the 
balun itself or connections to it may be faulty.


The point now is that I have discovered some damage to the outer 
covering of the sleeve 'balun' which may be the result of ferrites 
overheating or may be the cause of movement of the ferrites thus 
causing instability. Either way, heftier devices seem to be the order 
of the day.


Although the KPA500 temperature rise is somewhat expected, I feel it's 
a bit higher over a short period than I would like and may be due to 
reflected power.


73,

Alan. G4GNX



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Re: [Elecraft] NOT the feedline

[Alan - G4GNX]

I have a similar issue with ferrite 'balun' heating, although mostly 
tested on 40 metres. I'm using an OSCFD (Windom) which has a main 4:1 
balun at the feed point, but also has a sleeve 'balun' consisting of 8 
ferrites wrapped in a plastic sleeve, about 3 feet from the feed point. 
If I run the K3S at 100W, via the KPA500 in standby, then through the 
KAT500 tuner, I see no problems.


On increasing the power to 200W by using the KPA500 in Operate and about 
10W drive from the K3S, during a SSB 'over' the temperature of the 
KPA500 rises and after a few minutes, the SWR readings on the KPA500 and 
KAT500 start to rise. One of the Elecraft guys actually very kindly went 
through my fault log and came to the conclusion that the fault is with 
the antenna/feeder and I agree with him. What is strange is that if I 
leave a solid carrier running at 200W, I can't easily reproduce the 
issue and I wonder if its something being affected by peak excursions 
with SSB?


When things do start to go wrong, I can usually perform a manual tune 
with the KAT500 and the fault will then not (mostly) be apparent.


Anyway, I'm in the process of replacing the entire feeder with Westflex 
103 and much bigger ferrites. I will also replace the main balun which 
is a 400W device for a 1KW device, as I think that running the UK max of 
400W may be pushing the spec of a 400W balun. Also, the balun itself or 
connections to it may be faulty.


The point now is that I have discovered some damage to the outer 
covering of the sleeve 'balun' which may be the result of ferrites 
overheating or may be the cause of movement of the ferrites thus causing 
instability. Either way, heftier devices seem to be the order of the 
day.


Although the KPA500 temperature rise is somewhat expected, I feel it's a 
bit higher over a short period than I would like and may be due to 
reflected power.


73,

Alan. G4GNX


-- Original Message --
From: "David Olean" 
To: "Peter Dougherty" 
Cc: elecraft@mailman.qth.net
Sent: 01/06/2020 13:25:18
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; 
SWR issues)



Hello Peter

I suspect RFI as well. I do not have a KPA1500, so my advice is not worth much, 
but the fact that the fault only occurs when a signal is being radiated sends 
me a red flag.  I had a similar problem here with my SPE amplifier power 
output. I was measuring it on an LP-100A wattmeter.  It turns out that 1.8 MHz 
energy from the SPE amp radiated from my vertical antenna and  was getting into 
a new wire doublet antenna and coming back down the ladder line into the shack. 
The ladder line was about 7 inches from the power coupler for the LP-100A. RF 
caused the readings to go wacky and it looked like my amplifier was going 
postal!  The problem was high rf fields next to the power meter coupler.

Ferrite balun heating can be seen with a VSWR meter if you set the power at 
some intermediate level, key the amp up with a steady carrier, and watch for 
VSWR creeping up.  Loose pins in coax can also be a problem. They can heat up 
and disconnect or start arcing. Those problems do not typically show VSWR 
creep. They happen all at once usually.

The KPA1500 works fine into a dummy load. (No RFI)  That is a big clue.   Good 
luck and I hope you find the problem. Maybe an RF sniffer would detect the 
ingress point?

73

Dave K1WHS



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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[stephen shearer]

Ground loops can be another issue.
I was having a "feed back" issue with my KX3/KXPA100 ans solved it 
eliminating ground/power loops.


73, steve WB3LGC

On 6/1/20 8:25 AM, David Olean wrote:

Hello Peter

I suspect RFI as well. I do not have a KPA1500, so my advice is not 
worth much, but the fact that the fault only occurs when a signal is 
being radiated sends me a red flag.  I had a similar problem here with 
my SPE amplifier power output. I was measuring it on an LP-100A 
wattmeter.  It turns out that 1.8 MHz energy from the SPE amp radiated 
from my vertical antenna and  was getting into a new wire doublet 
antenna and coming back down the ladder line into the shack. The ladder 
line was about 7 inches from the power coupler for the LP-100A. RF 
caused the readings to go wacky and it looked like my amplifier was 
going postal!  The problem was high rf fields next to the power meter 
coupler.


Ferrite balun heating can be seen with a VSWR meter if you set the power 
at some intermediate level, key the amp up with a steady carrier, and 
watch for VSWR creeping up.  Loose pins in coax can also be a problem. 
They can heat up and disconnect or start arcing. Those problems do not 
typically show VSWR creep. They happen all at once usually.


The KPA1500 works fine into a dummy load. (No RFI)  That is a big 
clue.   Good luck and I hope you find the problem. Maybe an RF sniffer 
would detect the ingress point?


73

Dave K1WHS


On 6/1/2020 5:24 AM, Eric Norris wrote:

Is there any chance RF is getting in to the KPA1500 via an alternative
route, like one of your HF antennas, a faulty switch, loose 
bonding/ground,

or even a change in house wiring or wifi router, antenna rotator cable,
picking up the RF and radiating/routing it to the KPA1500 from the
antenna?  It's a shot in the dark, I know, but cut out everything but the
direct signal path originating from the K3, pull all the house 
breakers not

used, turn off everything--make only the 6m path active and see what
happens if this makes sense to you.

I feel your frustration--the same thing in reverse took out my 2m EME
station. I replaced every single thing, sent the K3 to Elecraft, the 
XV144

to Don...GUD LUCK OM!

VY 73 Eric WD6DBM

On Sun, May 31, 2020, 9:07 PM Peter Dougherty  wrote:

New coax and old coax behaved identically. HOWEVER, running into 
about 80
feet of old RG-213 and into the Cantenna dummy load and it doesn't 
fault.
This is the only condition on 6m where there is no fault. Brand new 
coax,
old coax, brand new antenna, old antenna, with balun, without balun. 
Always

faults except when feeding the pure resistive dummy load. If there's any
reactance it trips or gives false SWR info.

I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts
of drive? On the regular HF bands I can use the internal tuner to 
take out

a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..

  - pjd

-Original Message-
From: Adrian 
Sent: Sunday, May 31, 2020 11:05 PM
To: Peter Dougherty ; 'Paul Baldock' <
p...@paulbaldock.com>; elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 
6m; SWR

issues)

To remove any doubt, a 1.5kw or close dummy load at the end of the 
coax to

replace antenna, would confirm the amp issue.

On 1/6/20 12:27 pm, Peter Dougherty wrote:

Paul, please re-read what I wrote. The 90W figure is with the amp IN
STANDBY! I wouldn't dream of putting more than about 35W into the

KPA-1500.

I generally like to run about 1200W on 6m, but even if I turn my K3s
drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT
OF DRIVE from the K3s will stop these problems. If the amp is set to
deliver power it's going to fault on 6m, regardless of what the ATU is
set for (bypass or inline), and the KPA will miss-read the SWR of the

antenna system.

The resistance figure is 50.8 Ohms, and the reactance is -11 according
to the AA-230. The only difference between "works reliably" and
"faults out all the time" is one is a resistive-only load, the other
has a reactive component.

   - pjd

-


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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Dave Cole]

Peter,

If my antenna system had 2.5 to 3 to 1 SWR, I would not run 1.5 KW.  I'd 
be looking at my antenna...


73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources

On 5/31/20 9:07 PM, Peter Dougherty wrote:


I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of 
drive? On the regular HF bands I can use the internal tuner to take out a 2.5 
or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..

  - pjd

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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[David Olean]

Hello Peter

I suspect RFI as well. I do not have a KPA1500, so my advice is not 
worth much, but the fact that the fault only occurs when a signal is 
being radiated sends me a red flag.  I had a similar problem here with 
my SPE amplifier power output. I was measuring it on an LP-100A 
wattmeter.  It turns out that 1.8 MHz energy from the SPE amp radiated 
from my vertical antenna and  was getting into a new wire doublet 
antenna and coming back down the ladder line into the shack. The ladder 
line was about 7 inches from the power coupler for the LP-100A. RF 
caused the readings to go wacky and it looked like my amplifier was 
going postal!  The problem was high rf fields next to the power meter 
coupler.


Ferrite balun heating can be seen with a VSWR meter if you set the power 
at some intermediate level, key the amp up with a steady carrier, and 
watch for VSWR creeping up.  Loose pins in coax can also be a problem. 
They can heat up and disconnect or start arcing. Those problems do not 
typically show VSWR creep. They happen all at once usually.


The KPA1500 works fine into a dummy load. (No RFI)  That is a big 
clue.   Good luck and I hope you find the problem. Maybe an RF sniffer 
would detect the ingress point?


73

Dave K1WHS


On 6/1/2020 5:24 AM, Eric Norris wrote:

Is there any chance RF is getting in to the KPA1500 via an alternative
route, like one of your HF antennas, a faulty switch, loose bonding/ground,
or even a change in house wiring or wifi router, antenna rotator cable,
picking up the RF and radiating/routing it to the KPA1500 from the
antenna?  It's a shot in the dark, I know, but cut out everything but the
direct signal path originating from the K3, pull all the house breakers not
used, turn off everything--make only the 6m path active and see what
happens if this makes sense to you.

I feel your frustration--the same thing in reverse took out my 2m EME
station. I replaced every single thing, sent the K3 to Elecraft, the XV144
to Don...GUD LUCK OM!

VY 73 Eric WD6DBM

On Sun, May 31, 2020, 9:07 PM Peter Dougherty  wrote:


New coax and old coax behaved identically. HOWEVER, running into about 80
feet of old RG-213 and into the Cantenna dummy load and it doesn't fault.
This is the only condition on 6m where there is no fault. Brand new coax,
old coax, brand new antenna, old antenna, with balun, without balun. Always
faults except when feeding the pure resistive dummy load. If there's any
reactance it trips or gives false SWR info.

I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts
of drive? On the regular HF bands I can use the internal tuner to take out
a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..

  - pjd

-Original Message-
From: Adrian 
Sent: Sunday, May 31, 2020 11:05 PM
To: Peter Dougherty ; 'Paul Baldock' <
p...@paulbaldock.com>; elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR
issues)

To remove any doubt, a 1.5kw or close dummy load at the end of the coax to
replace antenna, would confirm the amp issue.

On 1/6/20 12:27 pm, Peter Dougherty wrote:

Paul, please re-read what I wrote. The 90W figure is with the amp IN
STANDBY! I wouldn't dream of putting more than about 35W into the

KPA-1500.

I generally like to run about 1200W on 6m, but even if I turn my K3s
drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT
OF DRIVE from the K3s will stop these problems. If the amp is set to
deliver power it's going to fault on 6m, regardless of what the ATU is
set for (bypass or inline), and the KPA will miss-read the SWR of the

antenna system.

The resistance figure is 50.8 Ohms, and the reactance is -11 according
to the AA-230. The only difference between "works reliably" and
"faults out all the time" is one is a resistive-only load, the other
has a reactive component.

   - pjd

-


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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Jim Brown]

On 5/31/2020 7:22 PM, Peter Dougherty wrote:

This is a brand-new balun from InnovAntennas, made specifically for this
antenna, received this past Thursday.


The word "balun" has been used to describe nearly a dozen VERY different 
physical things, and is thus totally useless as a descriptor of what you 
used (or what they sold you). Buy me a case of a good single malt Scotch 
and I'll run down the list.


I have extensively studied only one set of those "things," common mode 
chokes formed by winding a length of transmission line onto a ferrite 
core that is lossy at the frequency(ies) of interest, forming a parallel 
resonance in the common mode circuit where the RESISTIVE component of 
the low-Q parallel resonance is what makes the choke work.


A good common mode choke does not interact with a well-designed antenna 
unless the Zo of the transmission line wound onto the ferrite core is 
mismatched to the antenna. And I emphatically do NOT call them "baluns" 
because use of that word obscures understanding of HOW they work.


73, Jim K9YC
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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Eric Norris]

Is there any chance RF is getting in to the KPA1500 via an alternative
route, like one of your HF antennas, a faulty switch, loose bonding/ground,
or even a change in house wiring or wifi router, antenna rotator cable,
picking up the RF and radiating/routing it to the KPA1500 from the
antenna?  It's a shot in the dark, I know, but cut out everything but the
direct signal path originating from the K3, pull all the house breakers not
used, turn off everything--make only the 6m path active and see what
happens if this makes sense to you.

I feel your frustration--the same thing in reverse took out my 2m EME
station. I replaced every single thing, sent the K3 to Elecraft, the XV144
to Don...GUD LUCK OM!

VY 73 Eric WD6DBM

On Sun, May 31, 2020, 9:07 PM Peter Dougherty  wrote:

> New coax and old coax behaved identically. HOWEVER, running into about 80
> feet of old RG-213 and into the Cantenna dummy load and it doesn't fault.
> This is the only condition on 6m where there is no fault. Brand new coax,
> old coax, brand new antenna, old antenna, with balun, without balun. Always
> faults except when feeding the pure resistive dummy load. If there's any
> reactance it trips or gives false SWR info.
>
> I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts
> of drive? On the regular HF bands I can use the internal tuner to take out
> a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..
>
>  - pjd
>
> -Original Message-
> From: Adrian 
> Sent: Sunday, May 31, 2020 11:05 PM
> To: Peter Dougherty ; 'Paul Baldock' <
> p...@paulbaldock.com>; elecraft@mailman.qth.net
> Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR
> issues)
>
> To remove any doubt, a 1.5kw or close dummy load at the end of the coax to
> replace antenna, would confirm the amp issue.
>
> On 1/6/20 12:27 pm, Peter Dougherty wrote:
> > Paul, please re-read what I wrote. The 90W figure is with the amp IN
> > STANDBY! I wouldn't dream of putting more than about 35W into the
> KPA-1500.
> > I generally like to run about 1200W on 6m, but even if I turn my K3s
> > drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT
> > OF DRIVE from the K3s will stop these problems. If the amp is set to
> > deliver power it's going to fault on 6m, regardless of what the ATU is
> > set for (bypass or inline), and the KPA will miss-read the SWR of the
> antenna system.
> >
> > The resistance figure is 50.8 Ohms, and the reactance is -11 according
> > to the AA-230. The only difference between "works reliably" and
> > "faults out all the time" is one is a resistive-only load, the other
> > has a reactive component.
> >
> >   - pjd
> >
> > -
> >
>
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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Wes]

In an earlier message on a different, but related thread: 
http://elecraft.365791.n2.nabble.com/K3-SWR-Numerical-Indication-td7643839.html


I wrote:

"I would be surprised if two garden variety instruments, even placed at the same
point, would agree. The directional bridges/couplers in most "(V)SWR" meters
that hams routinely use externally or which are built into our radios are not
precision instruments.  There are a number of error sources in reflection
measurements; source match, diode non-linearity, coupler tracking errors and
often the most significant, directivity error.

In an ideal coupler, (i.e signal separation device) one port measures the
forward (incident signal) and another measures the reverse (reflected) signal
and there is no coupling between ports in the unwanted direction(s).  In other
words there is no signal at the reverse port due to the forward signal.  In a
real world coupler there is some leakage signal appearing at the reverse port
due to the forward signal, absent any reflected signal.  The "goodness" of a
directional coupler in this instance is called "directivity" and the error
signal is directivity error. Directivity is usually specified in dB.  Really
good couplers might have directivities in the 40 dB neighborhood. Really really
good directional bridges can be 50 dB, but so-so units might be 25-30 dB.  Not
ready for prime time units are lower than this.

Now I have no way of knowing what the directivities are of the couplers built
into K3s, KPA500s, KAT500s, etc. but considering that they have to work over
about 5 octaves, I'm going out on a limb and saying that 25 to 30 dB is a fair
estimate.  If I'm wrong, I'm sure I'll hear about it.  For sake of discussion
I'm going to use 26.5 dB.  What this means is that if I terminate the output
spigot of one of these radios with a perfect 50+j0 load, I'm going to measure a
leakage signal (directivity error) that is 26.5 dB below the incident value.
I'll introduce the concept of return loss here.

We hams usually speak in terms of SWR.  SWR = (1 + p) / (1 - p) where p is the
reflection coefficient. Here the p = the voltage measured at the reflected port
and the constant 1 represents the incident signal.  In reality both of these
quantities are complex numbers, they have both magnitude and phase but SWR
measurements are scalar, we throw away the phase (since it's difficult to
measure) and just use the magnitude. (In fact the symbol "p", which is really
the Greek letter rho, indicates the magnitude of the reflection coefficient in
normal usage)  We can also express this ratio as return loss, which is -20 *
log10(p).  So return loss, SWR and reflection coefficient are just different
ways to express the same thing; the ratio of incident to reflected signal.

Let's return to our example; the coupler with 26.5 dB directivity, which
indicates a return loss (RL) of 26.5 dB even with a perfect termination.  Doing
the math and converting RL = 26.5 dB to SWR we get 1.1:1.  Our perfect load
measures 1.1:1 with our imperfect instrument.  And this assumes that there are
no other errors, which there always are. But it gets worse.

Let's say that the load we want to measure really is 1.1:1.  We now have two
(apparent) reflections, 1) the real one and 2) the directivity error and they
both have the same magnitude.  In our simple detector, they sum together.  Now I
said earlier that we don't measure phase, only magnitude, but just because we
don't, or can't measure the relative phases doesn't mean they aren't there. We
will examine two cases to determine the limits of error.  Case 1) both
reflections are in phase, they add up to p + p or 2p, RL = 20.5 and SWR
~1.21:1.  Case 2) they are exactly out of phase, they sum to zero.  p = 0, RL is
infinite and SWR = 1:1.  The possible RL error is then -6 to +infinity dB!

In other words, an actual SWR of 1.1:1 can be measured anywhere between 1.0:1
and 1.2:1.  Is it any wonder that we often read about concerns that one device
measures one thing, while another located at the same, or close location
measures something different.  Of course all of this is predicated on a
directional coupler with 26.5 dB directivity and no other error sources.  It's
entirely possible that the Elecraft couplers are better than this.  They are
certainly no better than 40 dB since the internal reference resistors are 51
instead of 50 ohm.  Plus the "Tandem Match" configuration is in itself not a
great match to the transmitter output.(1)  Furthermore, the coupler, at least in
a K3 is driven by a LPF, which isn't a great 50 ohm source. Plus the coupler
output port isn't connected directly to the coax connector. and so on and so
forth (2).  All of this creates "uncertainty."

In a metrology lab heroic efforts are made to reduce uncertainty but do we, or
should we, really care in this situation?  In my opinion, no, but everyone is
free to differ.

Wes  N7WS

(1)  See "An HF In-Line Return Loss And Power Meter" by Paul Kiciak, N2PK.

Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Lou W0FK]

What are the error codes when you hard fault? Check them and see if there’s
any consistency.

 I sometimes get hard faults when I’ve moved my rf deck, simply because the
PowerPoles on the 12v line from the power supply have moved a bit and aren’t
making a good connection. I usually see a 50v warning pop up that alerts me
to the issue.  Have you made sure that 12v line is secured?

I also concur that 90 watts Drive into the amp is way too much. That
suggests the amp is the culprit. The innovantenna balun is pretty robust.
But if you suspect it, bypass it and test a direct line with pigtailed ends
directly into the loop.

73, Lou W0FK





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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Mark Goldberg]

I haven't seen a discussion of your grounding system or feedline length. 6M
can be picky.  What does your ground system look like? Do you have any
common mode chokes on the feedline? Have you tried adding or subtracting
2-3 feet from the feedline? If it is exactly a multiple of 1/2 wave or 1/4
wave changing the feedline length will move it away from that. Have you
tried adding a counterpoise in the shack? That's not the ultimate solution
but if it improves things it will tell you something. Can you point an IR
thermometer at tuner / balun inductors to see if they are getting hot? Just
throwing out ideas.

73,

Mark
W7MLG


On Sun, May 31, 2020 at 9:08 PM Peter Dougherty  wrote:

> New coax and old coax behaved identically. HOWEVER, running into about 80
> feet of old RG-213 and into the Cantenna dummy load and it doesn't fault.
> This is the only condition on 6m where there is no fault. Brand new coax,
> old coax, brand new antenna, old antenna, with balun, without balun. Always
> faults except when feeding the pure resistive dummy load. If there's any
> reactance it trips or gives false SWR info.
>
> I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts
> of drive? On the regular HF bands I can use the internal tuner to take out
> a 2.5 or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..
>
>  - pjd
>
>
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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Vic Rosenthal]

Are you using the same output connector on the KPA1500 for the dummy load and 
the antenna? 
Perhaps the problem is in one of the SO239s or in the KPA’s switching circuit?

Victor 4X6GP 

> On 1 Jun 2020, at 4:30, Peter Dougherty  wrote:
> 
> Many here suggested that it was most likely a feedline issue, and I figured
> this was indeed a distinct possibility. 
> 
> So this afternoon I replaced the feedline. I now have about 80 feet of brand
> new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun
> since I don't have any type-N connectors here). The AA-230 ZOOM analyzer
> shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix
> that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. 
> 
> The TDR screen looks very clean, just a tiny bump where the feedline goes
> through the (new) bulkhead connector to get into the house. See:
> https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0
> 
> The SWR chart between 50.000 and 50.500:
> https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0
> 
> Again, I know the antenna is resonant a bit low, but this should NOT be a
> factor. So here's what's now going on.
> 
> 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500
> is delivering 1075W and showing 1.4:1. No problem delivering power and no
> faults.
> 
> 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the
> Cantenna. Again, no problem delivering power to the purely resistive load.
> Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second
> periods without issue.
> 
> 3) When I switch over to the live antenna, with25 Watts of drive from the
> K3s into the actual antenna and the amp faults out instantly in bypass. When
> the amplifier is in bypass and the tuner is in bypass, and when the K3s is
> delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the
> SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR
> of 1.4:1. 
> 
> 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front
> panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine
> like this, right?
> 
> 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner
> in and untouched since step 4), the amp SOMETIMES delivers power, sometimes
> faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to
> use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with
> 90W of K3s drive.
> 
> 6) There is basically no rhyme or reason why this is happening and it's
> *somewhat* repeatable. The incredibly frustrating part is if I see a needed
> station come up, I'll flick the amp's tuner in line and it says it's tuned.
> Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If
> it doesn't fault on the first transmission, it absolutely WILL on the second
> transmission. 
> 
> So I'm now at a complete loss to understand what's going on here. Amp is
> fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline,
> brand new connectors, the KPA-1500 is faulting out the same as it did on the
> 10+ year old 6M5 with a patchwork of feedlines. I can't see how this is
> anything but a problem in the KPA-1500 (S/N 0398).
> 
> - pjd
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net  On
> Behalf Of Jim Brown
> Sent: Sunday, May 31, 2020 8:22 PM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues
> 
>> On 5/31/2020 9:54 AM, Jim Miller wrote:
>> Have you vetted your feedline at 1500w? Many times something might be 
>> good at low power and fail at 1500.
> 
> This is good advice. Guys who do lots of portable setup say to always check
> the coax first, which mostly means check for a connector that's bad or badly
> installed.
> 
> In general, if it doesn't say Amphenol or isn't stamped with a MIL spec
> number, it's very likely to be poor quality. This includes barrels,
> adapters, etc.  Also make sure that every connector is" wrench tight."
> 
> The advice to run it straight to a dummy load is right on -- if you have one
> big enough. :)
> 
> 73, Jim K9YC
> __
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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

New coax and old coax behaved identically. HOWEVER, running into about 80 feet 
of old RG-213 and into the Cantenna dummy load and it doesn't fault. This is 
the only condition on 6m where there is no fault. Brand new coax, old coax, 
brand new antenna, old antenna, with balun, without balun. Always faults except 
when feeding the pure resistive dummy load. If there's any reactance it trips 
or gives false SWR info.

I would also add, why would a 2:1 SWR trip out the amp at 25 or 30 Watts of 
drive? On the regular HF bands I can use the internal tuner to take out a 2.5 
or 3:1 SWR and it still sends 1400-1450 Watts up the pipe..

 - pjd

-Original Message-
From: Adrian  
Sent: Sunday, May 31, 2020 11:05 PM
To: Peter Dougherty ; 'Paul Baldock' ; 
elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR 
issues)

To remove any doubt, a 1.5kw or close dummy load at the end of the coax to 
replace antenna, would confirm the amp issue.

On 1/6/20 12:27 pm, Peter Dougherty wrote:
> Paul, please re-read what I wrote. The 90W figure is with the amp IN 
> STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500.
> I generally like to run about 1200W on 6m, but even if I turn my K3s 
> drive down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT 
> OF DRIVE from the K3s will stop these problems. If the amp is set to 
> deliver power it's going to fault on 6m, regardless of what the ATU is 
> set for (bypass or inline), and the KPA will miss-read the SWR of the antenna 
> system.
>
> The resistance figure is 50.8 Ohms, and the reactance is -11 according 
> to the AA-230. The only difference between "works reliably" and 
> "faults out all the time" is one is a resistive-only load, the other 
> has a reactive component.
>
>   - pjd
>
> -
>

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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Adrian]

To remove any doubt, a 1.5kw or close dummy load at the end of the coax 
to replace antenna, would confirm the amp issue.


On 1/6/20 12:27 pm, Peter Dougherty wrote:

Paul, please re-read what I wrote. The 90W figure is with the amp IN
STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500.
I generally like to run about 1200W on 6m, but even if I turn my K3s drive
down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT OF DRIVE
from the K3s will stop these problems. If the amp is set to deliver power
it's going to fault on 6m, regardless of what the ATU is set for (bypass or
inline), and the KPA will miss-read the SWR of the antenna system.

The resistance figure is 50.8 Ohms, and the reactance is -11 according to
the AA-230. The only difference between "works reliably" and "faults out all
the time" is one is a resistive-only load, the other has a reactive
component.

  - pjd

-


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Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

Paul, please re-read what I wrote. The 90W figure is with the amp IN
STANDBY! I wouldn't dream of putting more than about 35W into the KPA-1500.
I generally like to run about 1200W on 6m, but even if I turn my K3s drive
down to 20 Watts, it will STILL hard-fault regularly. NO AMOUNT OF DRIVE
from the K3s will stop these problems. If the amp is set to deliver power
it's going to fault on 6m, regardless of what the ATU is set for (bypass or
inline), and the KPA will miss-read the SWR of the antenna system. 

The resistance figure is 50.8 Ohms, and the reactance is -11 according to
the AA-230. The only difference between "works reliably" and "faults out all
the time" is one is a resistive-only load, the other has a reactive
component.

 - pjd

-Original Message-
From: Paul Baldock  
Sent: Sunday, May 31, 2020 10:06 PM
To: Peter Dougherty ; elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR
issues)

A few things I observe on my KPA 1500:

On 6m the KPA1500 reads 1.3/1.4:1 into a perfect load.  FYI it reads
1.2:1 in to a perfect load on 10M also, but 1.0:1 on all other
bands.Elecraft have various excuses for this.

1500W its really pushing it on 6M. Way to much compression. I run mine at
1100W out with 38W drive. as you state 90W, that's way too much drive.

As the amp warms up the output drops (on all bands), but I never exceed 38W
drive on 6M.

On FT8 I drive it to 500W out only, and the amp stays reasonably cool.

On 6M I bypass the tuner as the real antenna SWR is less than 1.5:1, and I
ignore what the KP1500 says it is.

Try the amp the way I use it and see how it goes.

Good luck

- Paul KW7Y



At 06:29 PM 5/31/2020, you wrote:
>Many here suggested that it was most likely a feedline issue, and I 
>figured this was indeed a distinct possibility.
>
>So this afternoon I replaced the feedline. I now have about 80 feet of 
>brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at 
>the balun since I don't have any type-N connectors here). The AA-230 
>ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below 
>the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to the
KPA.
>
>The TDR screen looks very clean, just a tiny bump where the feedline 
>goes through the (new) bulkhead connector to get into the house. See:
>https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=
>0
>
>The SWR chart between 50.000 and 50.500:
>https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=
>0
>
>Again, I know the antenna is resonant a bit low, but this should NOT be 
>a factor. So here's what's now going on.
>
>1) Into a Cantenna dummy load, with 25W of drive from the M3s, the 
>KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering 
>power and no faults.
>
>2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into 
>the Cantenna. Again, no problem delivering power to the purely resistive
load.
>Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 
>second periods without issue.
>
>3) When I switch over to the live antenna, with25 Watts of drive from 
>the K3s into the actual antenna and the amp faults out instantly in 
>bypass. When the amplifier is in bypass and the tuner is in bypass, and 
>when the K3s is delivering about 90W in FT8 mode, the front panel on 
>the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on the 
>radio, it's showing an SWR of 1.4:1.
>
>4) Amp in bypass, tuner inline, press TUNE button on the K3s and the 
>front panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD 
>work fine like this, right?
>
>5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA 
>tuner in and untouched since step 4), the amp SOMETIMES delivers power, 
>sometimes faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY 
>button again to use only exciter power, and touching NOTHING ELSE, it's 
>back to 1.1:1 with 90W of K3s drive.
>
>6) There is basically no rhyme or reason why this is happening and it's
>*somewhat* repeatable. The incredibly frustrating part is if I see a 
>needed station come up, I'll flick the amp's tuner in line and it says it's
tuned.
>Once WSJT-X keys the radio, 90 out of 100 times the amp will 
>hard-fault. If it doesn't fault on the first transmission, it 
>absolutely WILL on the second transmission.
>
>So I'm now at a complete loss to understand what's going on here. Amp 
>is fine into a resistive load. Brand-new antenna, brand new LMR-400 
>feedline, brand new connectors, the KPA-1500 is faulting out the same 
>as it did on the
>10+ year old 6M5 with a patchwork of feedlines. I can't see how this is
>anything but a problem in the KPA-1500 (S/N 0398).
>
>  - pjd
>
>-Original Message--

Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

This is a brand-new balun from InnovAntennas, made specifically for this
antenna, received this past Thursday. 

Note that exactly what I described was also occurring on my old setup, on an
antenna without a balun feed. 

Basically everything from the output SO-239 on the KPA-1500 on up to the top
of the tower has been replaced with brand new everything. The fault
conditions are identical to what was happening beforehand.

 - pjd

-Original Message-
From: Jack Brindle  
Sent: Sunday, May 31, 2020 9:38 PM
To: Peter Dougherty 
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR
issues)

Balun? Is it new? What kind?
You have pretty much eliminated the KPA1500 with this test. This sounds like
a balun toroid heating up and causing problems. 
You will see perfect conditions at low power, and the AA230 will also show
things in great shape. They are not stressing the system. But 1500 watts
sure will.
Talk a better look at the antenna system. And the balun. Open it up if
possible.

And, again describe, in detail the antenna system. There is something there
to be found.

73!
Jack, W6FB


> On May 31, 2020, at 6:29 PM, Peter Dougherty  wrote:
> 
> Many here suggested that it was most likely a feedline issue, and I 
> figured this was indeed a distinct possibility.
> 
> So this afternoon I replaced the feedline. I now have about 80 feet of 
> brand new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at 
> the balun since I don't have any type-N connectors here). The AA-230 
> ZOOM analyzer shows about 1.2:1 at 50.313, with resonance just below 
> the band. I'll fix that tomorrow, but 1.2 or 1.3:1 should be nothing to
the KPA.
> 
> The TDR screen looks very clean, just a tiny bump where the feedline 
> goes through the (new) bulkhead connector to get into the house. See:
> https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl
> =0
> 
> The SWR chart between 50.000 and 50.500:
> https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl
> =0
> 
> Again, I know the antenna is resonant a bit low, but this should NOT 
> be a factor. So here's what's now going on.
> 
> 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the 
> KPA-1500 is delivering 1075W and showing 1.4:1. No problem delivering 
> power and no faults.
> 
> 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 
> into the Cantenna. Again, no problem delivering power to the purely
resistive load.
> Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 
> second periods without issue.
> 
> 3) When I switch over to the live antenna, with25 Watts of drive from 
> the K3s into the actual antenna and the amp faults out instantly in 
> bypass. When the amplifier is in bypass and the tuner is in bypass, 
> and when the K3s is delivering about 90W in FT8 mode, the front panel 
> on the KPA-1500 says the SWR is 1.9:1. When I press the TUNE button on 
> the radio, it's showing an SWR of 1.4:1.
> 
> 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the 
> front panel of the KPA-1500 is showing a perfect 1.0:1 match. It 
> SHOULD work fine like this, right?
> 
> 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA 
> tuner in and untouched since step 4), the amp SOMETIMES delivers 
> power, sometimes faults out, shows an SWR of 1.7:1. Pressing the 
> OPER/STBY button again to use only exciter power, and touching NOTHING 
> ELSE, it's back to 1.1:1 with 90W of K3s drive.
> 
> 6) There is basically no rhyme or reason why this is happening and 
> it's
> *somewhat* repeatable. The incredibly frustrating part is if I see a 
> needed station come up, I'll flick the amp's tuner in line and it says
it's tuned.
> Once WSJT-X keys the radio, 90 out of 100 times the amp will 
> hard-fault. If it doesn't fault on the first transmission, it 
> absolutely WILL on the second transmission.
> 
> So I'm now at a complete loss to understand what's going on here. Amp 
> is fine into a resistive load. Brand-new antenna, brand new LMR-400 
> feedline, brand new connectors, the KPA-1500 is faulting out the same 
> as it did on the
> 10+ year old 6M5 with a patchwork of feedlines. I can't see how this 
> 10+ is
> anything but a problem in the KPA-1500 (S/N 0398).
> 
> - pjd
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net 
>  On Behalf Of Jim Brown
> Sent: Sunday, May 31, 2020 8:22 PM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues
> 
> On 5/31/2020 9:54 AM, Jim Miller wrote:
>> Have you vetted your feedline at 1500w? Many times something might be 
>> good at low power and fail at 1500.
> 
> This is good advice. Guys who d

Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Paul Baldock]

A few things I observe on my KPA 1500:

On 6m the KPA1500 reads 1.3/1.4:1 into a perfect load.  FYI it reads 
1.2:1 in to a perfect load on 10M also, but 1.0:1 on all other 
bands.Elecraft have various excuses for this.


1500W its really pushing it on 6M. Way to much compression. I run 
mine at 1100W out with 38W drive. as you state 90W, that's way too much drive.


As the amp warms up the output drops (on all bands), but I never 
exceed 38W drive on 6M.


On FT8 I drive it to 500W out only, and the amp stays reasonably cool.

On 6M I bypass the tuner as the real antenna SWR is less than 1.5:1, 
and I ignore what the KP1500 says it is.


Try the amp the way I use it and see how it goes.

Good luck

- Paul KW7Y



At 06:29 PM 5/31/2020, you wrote:

Many here suggested that it was most likely a feedline issue, and I figured
this was indeed a distinct possibility.

So this afternoon I replaced the feedline. I now have about 80 feet of brand
new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun
since I don't have any type-N connectors here). The AA-230 ZOOM analyzer
shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix
that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA.

The TDR screen looks very clean, just a tiny bump where the feedline goes
through the (new) bulkhead connector to get into the house. See:
https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0

The SWR chart between 50.000 and 50.500:
https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0

Again, I know the antenna is resonant a bit low, but this should NOT be a
factor. So here's what's now going on.

1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500
is delivering 1075W and showing 1.4:1. No problem delivering power and no
faults.

2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the
Cantenna. Again, no problem delivering power to the purely resistive load.
Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second
periods without issue.

3) When I switch over to the live antenna, with25 Watts of drive from the
K3s into the actual antenna and the amp faults out instantly in bypass. When
the amplifier is in bypass and the tuner is in bypass, and when the K3s is
delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the
SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR
of 1.4:1.

4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front
panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine
like this, right?

5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner
in and untouched since step 4), the amp SOMETIMES delivers power, sometimes
faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to
use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with
90W of K3s drive.

6) There is basically no rhyme or reason why this is happening and it's
*somewhat* repeatable. The incredibly frustrating part is if I see a needed
station come up, I'll flick the amp's tuner in line and it says it's tuned.
Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If
it doesn't fault on the first transmission, it absolutely WILL on the second
transmission.

So I'm now at a complete loss to understand what's going on here. Amp is
fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline,
brand new connectors, the KPA-1500 is faulting out the same as it did on the
10+ year old 6M5 with a patchwork of feedlines. I can't see how this is
anything but a problem in the KPA-1500 (S/N 0398).

 - pjd

-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Jim Brown
Sent: Sunday, May 31, 2020 8:22 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues

On 5/31/2020 9:54 AM, Jim Miller wrote:
> Have you vetted your feedline at 1500w? Many times something might be
> good at low power and fail at 1500.

This is good advice. Guys who do lots of portable setup say to always check
the coax first, which mostly means check for a connector that's bad or badly
installed.

In general, if it doesn't say Amphenol or isn't stamped with a MIL spec
number, it's very likely to be poor quality. This includes barrels,
adapters, etc.  Also make sure that every connector is" wrench tight."

The advice to run it straight to a dummy load is right on -- if you have one
big enough. :)

73, Jim K9YC
__
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__
Elecraft 

Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Jack Brindle via Elecraft]

Balun? Is it new? What kind?
You have pretty much eliminated the KPA1500 with this test. This sounds like a 
balun toroid heating up and causing problems. 
You will see perfect conditions at low power, and the AA230 will also show 
things in great shape. They are not stressing the system. But 1500 watts sure 
will.
Talk a better look at the antenna system. And the balun. Open it up if possible.

And, again describe, in detail the antenna system. There is something there to 
be found.

73!
Jack, W6FB


> On May 31, 2020, at 6:29 PM, Peter Dougherty  wrote:
> 
> Many here suggested that it was most likely a feedline issue, and I figured
> this was indeed a distinct possibility. 
> 
> So this afternoon I replaced the feedline. I now have about 80 feet of brand
> new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun
> since I don't have any type-N connectors here). The AA-230 ZOOM analyzer
> shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix
> that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. 
> 
> The TDR screen looks very clean, just a tiny bump where the feedline goes
> through the (new) bulkhead connector to get into the house. See:
> https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0
> 
> The SWR chart between 50.000 and 50.500:
> https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0
> 
> Again, I know the antenna is resonant a bit low, but this should NOT be a
> factor. So here's what's now going on.
> 
> 1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500
> is delivering 1075W and showing 1.4:1. No problem delivering power and no
> faults.
> 
> 2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the
> Cantenna. Again, no problem delivering power to the purely resistive load.
> Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second
> periods without issue.
> 
> 3) When I switch over to the live antenna, with25 Watts of drive from the
> K3s into the actual antenna and the amp faults out instantly in bypass. When
> the amplifier is in bypass and the tuner is in bypass, and when the K3s is
> delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the
> SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR
> of 1.4:1. 
> 
> 4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front
> panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine
> like this, right?
> 
> 5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner
> in and untouched since step 4), the amp SOMETIMES delivers power, sometimes
> faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to
> use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with
> 90W of K3s drive.
> 
> 6) There is basically no rhyme or reason why this is happening and it's
> *somewhat* repeatable. The incredibly frustrating part is if I see a needed
> station come up, I'll flick the amp's tuner in line and it says it's tuned.
> Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If
> it doesn't fault on the first transmission, it absolutely WILL on the second
> transmission. 
> 
> So I'm now at a complete loss to understand what's going on here. Amp is
> fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline,
> brand new connectors, the KPA-1500 is faulting out the same as it did on the
> 10+ year old 6M5 with a patchwork of feedlines. I can't see how this is
> anything but a problem in the KPA-1500 (S/N 0398).
> 
> - pjd
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net  On
> Behalf Of Jim Brown
> Sent: Sunday, May 31, 2020 8:22 PM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues
> 
> On 5/31/2020 9:54 AM, Jim Miller wrote:
>> Have you vetted your feedline at 1500w? Many times something might be 
>> good at low power and fail at 1500.
> 
> This is good advice. Guys who do lots of portable setup say to always check
> the coax first, which mostly means check for a connector that's bad or badly
> installed.
> 
> In general, if it doesn't say Amphenol or isn't stamped with a MIL spec
> number, it's very likely to be poor quality. This includes barrels,
> adapters, etc.  Also make sure that every connector is" wrench tight."
> 
> The advice to run it straight to a dummy load is right on -- if you have one
> big enough. :)
> 
> 73, Jim K9YC
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> delivered to li...@w2irt.net 
> 
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> Elecraft 

Re: [Elecraft] NOT the feedline (was KPA-1500 faulting on 6m; SWR issues)

[Peter Dougherty]

Many here suggested that it was most likely a feedline issue, and I figured
this was indeed a distinct possibility. 

So this afternoon I replaced the feedline. I now have about 80 feet of brand
new LMR-400, new 83-SP1 connectors (and an Amphenol adaptor at the balun
since I don't have any type-N connectors here). The AA-230 ZOOM analyzer
shows about 1.2:1 at 50.313, with resonance just below the band. I'll fix
that tomorrow, but 1.2 or 1.3:1 should be nothing to the KPA. 

The TDR screen looks very clean, just a tiny bump where the feedline goes
through the (new) bulkhead connector to get into the house. See:
https://www.dropbox.com/s/izcwvece7nt5f42/2020-05-31%2019.32.44.jpg?dl=0

The SWR chart between 50.000 and 50.500:
https://www.dropbox.com/s/y2xh4l1lihy2ujr/2020-05-31%2021.23.29.jpg?dl=0

Again, I know the antenna is resonant a bit low, but this should NOT be a
factor. So here's what's now going on.

1) Into a Cantenna dummy load, with 25W of drive from the M3s, the KPA-1500
is delivering 1075W and showing 1.4:1. No problem delivering power and no
faults.

2) With input power increased, 35W of K3s drive gives 1375W at 1.5 into the
Cantenna. Again, no problem delivering power to the purely resistive load.
Why a 1.5:1, I don't know, but fine, whatever. I can TX for 15-20 second
periods without issue.

3) When I switch over to the live antenna, with25 Watts of drive from the
K3s into the actual antenna and the amp faults out instantly in bypass. When
the amplifier is in bypass and the tuner is in bypass, and when the K3s is
delivering about 90W in FT8 mode, the front panel on the KPA-1500 says the
SWR is 1.9:1. When I press the TUNE button on the radio, it's showing an SWR
of 1.4:1. 

4) Amp in bypass, tuner inline, press TUNE button on the K3s and the front
panel of the KPA-1500 is showing a perfect 1.0:1 match. It SHOULD work fine
like this, right?

5) Pressing ONLY the OPER/STBY button to put the amp in operate (KPA tuner
in and untouched since step 4), the amp SOMETIMES delivers power, sometimes
faults out, shows an SWR of 1.7:1. Pressing the OPER/STBY button again to
use only exciter power, and touching NOTHING ELSE, it's back to 1.1:1 with
90W of K3s drive.

6) There is basically no rhyme or reason why this is happening and it's
*somewhat* repeatable. The incredibly frustrating part is if I see a needed
station come up, I'll flick the amp's tuner in line and it says it's tuned.
Once WSJT-X keys the radio, 90 out of 100 times the amp will hard-fault. If
it doesn't fault on the first transmission, it absolutely WILL on the second
transmission. 

So I'm now at a complete loss to understand what's going on here. Amp is
fine into a resistive load. Brand-new antenna, brand new LMR-400 feedline,
brand new connectors, the KPA-1500 is faulting out the same as it did on the
10+ year old 6M5 with a patchwork of feedlines. I can't see how this is
anything but a problem in the KPA-1500 (S/N 0398).

 - pjd

-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Jim Brown
Sent: Sunday, May 31, 2020 8:22 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA-1500 faulting on 6m; SWR issues

On 5/31/2020 9:54 AM, Jim Miller wrote:
> Have you vetted your feedline at 1500w? Many times something might be 
> good at low power and fail at 1500.

This is good advice. Guys who do lots of portable setup say to always check
the coax first, which mostly means check for a connector that's bad or badly
installed.

In general, if it doesn't say Amphenol or isn't stamped with a MIL spec
number, it's very likely to be poor quality. This includes barrels,
adapters, etc.  Also make sure that every connector is" wrench tight."

The advice to run it straight to a dummy load is right on -- if you have one
big enough. :)

73, Jim K9YC
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Re: [Elecraft] Off topic feedline question

[Bill W4ZV]

Here's a thread on zipcord loss from years ago:

http://elecraft.365791.n2.nabble.com/What-your-mother-didn-t-tell-you-about-transmission-lines-td6780383.html

This is a real world result I observed:

"About 10 years ago ET3PMW was attempting to get on the low bands and only
had zip cord available for transmission line.  I thought it should work fine
for 80 and 160.  However, on 80m running 100 watts he was barely detectible
here using a 1200' Beverage for receive.  Once Paul got some good ladder
line, his signal was typically S8 on 80m and S6 on Topband, where he made
several hundred QSOs with North America even in summer QRN (June/July)."

Stay away from it until you can get decent ladder line!

73,  Bill  W4ZV



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Re: [Elecraft] Off topic feedline question

[Al Scanandoah]

If your main concerns are strength and durability, I'd recommend:
http://trueladderline.com
I've been pleased with the results I've had over the past 15 years.
Al, K2ZN


Sent via mobile
 Original message From: Michael Blake <k9...@mac.com> Date: 
11/7/17  11:12 AM  (GMT-05:00) To: Elecraft Mailing List 
<elecraft@mailman.qth.net> Subject: Re: [Elecraft] Off topic feedline question 
Thanks to all of you for your responses.  My need for a lower impedance 
parallel line is not so much a matter of loss but to minimize the impedance 
transformer effect a 25’ window line (400 ohm) has when terminated in a low 
impedance load.  My real concern was for the ability of the line to survive in 
weather and sunlight and its RF voltage breakdown rating.

The two data references were quite helpful.  Thanks again!

Michael Blake
k9...@mac.com

From: Michael Blake
Sent: Tuesday, November 7, 2017 9:12 AM
To: Elecraft Mailing List
Subject: [Elecraft] Off topic feedline question

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 90 
ohm range, and world certainly handle the applied power (500 watts) but I have 
not been able find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Off topic feedline question

[Wes Stewart]

You are mistaken. 25' of ladderline is only about a tenth of a wavelength and 
does not invert impedance. I suggest you download Dan's TLDetails program: 
http://ac6la.com/tldetails1.html and play with it.  Put in what you think, or 
have measured, the feedpoint Z is then select one of the Wireman ladderlines and 
see what happens as you change the length.


You may find some data on zip cord as feeders, but I would avoid them like the 
plague, particularly as you are trying to solve a problem that doesn't exist.


Wes  N7WS


On 11/7/2017 7:08 AM, Michael Blake wrote:
My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and 
terminates in a 1:1 balun which is then connected to a remote autotuner via 24 
inches of 9913F.


The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 
90 ohm range, and world certainly handle the applied power (500 watts) but I 
have not been able find any information regarding RF loss.


Michael Blake
k9...@mac.com 


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Re: [Elecraft] Off topic feedline question

[Wes Stewart]

I'm sending this again because I didn't see it come through:

You are mistaken. 25' of ladderline is only about a tenth of a wavelength and 
does not invert impedance. I suggest you download Dan's TLDetails program: 
http://ac6la.com/tldetails1.html and play with it.  Put in what you think, or 
have measured, the feedpoint Z is then select one of the Wireman ladderlines and 
see what happens as you change the length.


You may find some data on zip cord as feeders, but I would avoid them like the 
plague, particularly as you are trying to solve a problem that doesn't exist.


Wes  N7WS


On 11/7/2017 9:12 AM, Michael Blake wrote:

Thanks to all of you for your responses.  My need for a lower impedance 
parallel line is not so much a matter of loss but to minimize the impedance 
transformer effect a 25’ window line (400 ohm) has when terminated in a low 
impedance load.  My real concern was for the ability of the line to survive in 
weather and sunlight and its RF voltage breakdown rating.

The two data references were quite helpful.  Thanks again!

Michael Blake
k9...@mac.com

From: Michael Blake
Sent: Tuesday, November 7, 2017 9:12 AM
To: Elecraft Mailing List
Subject: [Elecraft] Off topic feedline question

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC insulated 
"speaker" wire.  The impedance would be quite low, probably in the 90 ohm 
range, and world certainly handle the applied power (500 watts) but I have not been able 
find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Off topic feedline question

[Michael Blake]

Thanks to all of you for your responses.  My need for a lower impedance 
parallel line is not so much a matter of loss but to minimize the impedance 
transformer effect a 25’ window line (400 ohm) has when terminated in a low 
impedance load.  My real concern was for the ability of the line to survive in 
weather and sunlight and its RF voltage breakdown rating.

The two data references were quite helpful.  Thanks again!

Michael Blake
k9...@mac.com

From: Michael Blake
Sent: Tuesday, November 7, 2017 9:12 AM
To: Elecraft Mailing List
Subject: [Elecraft] Off topic feedline question

My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 90 
ohm range, and world certainly handle the applied power (500 watts) but I have 
not been able find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Off topic feedline question

[Robert Cunnings]

Yes, googling "zip cord hf loss" yields the classic QST article:

http://www.w1npp.org/events/2010/2010-f~1/antennas/wire/790303~1.PDF

among others. Here are measurements made with a Rigexpert AA-600;

http://owenduffy.net/blog/?p=327

Bob NW8L

On Tue, 7 Nov 2017, Michael Blake wrote:


The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 
90 ohm range, and world certainly handle the applied power (500 watts) but I 
have not been able find any information regarding RF loss.


Michael Blake
k9...@mac.com__
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Re: [Elecraft] Off topic feedline question

[David Kuechenmeister]

I didn't study this site too deeply, but KP4MD has the most appropriate 
characteristics on her page, here, http://www.qsl.net/kp4md/zipcord.htm.
You might also look at Owen Duffy's pages. His transmission line calculator is 
great. I think the last entry for zip 105 is zip cord, but you should email him 
and ask. The page is at http://owenduffy.net/calc/tl/tllc.php
vy 73,Dave N4KD 

On Tuesday, November 7, 2017 9:12 AM, Michael Blake  wrote:
 

 My 80M antenna is a low, loaded dipole fed with balanced window line.  As the 
center impedance is  low the high impedance window line tries to invert the 
impedance to a much higher value.  The feedline is only 25' long and terminates 
in a 1:1 balun which is then connected to a remote autotuner via 24 inches of 
9913F.

The question is:

Has anyone run any RF loss tests on the commonly available 12 gauge clear PVC 
insulated "speaker" wire.  The impedance would be quite low, probably in the 90 
ohm range, and world certainly handle the applied power (500 watts) but I have 
not been able find any information regarding RF loss.

Michael Blake
k9...@mac.com
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Re: [Elecraft] Balanced Antenna Feedline Current Measurements

[John W2XS]

Let's try spaces instead of tabs for the tables.

Here's a summary of the sums of the scale readings (side1 plus side 2). 
Keep in mind that I may have switched scales from band to band but it is the
relative numbers in each row are all on the same scale.

BandJMBDirect4to11to1
  Sum   Sum   Sum Sum
160  X84 7175
80   73   62 6765
40   124 87108   84
30   93   75101   88
20   73   149   6142
17   140  117  135   117
15   75   808080
12   50   495755
10   70   657367
6 X 444445
  
Here's a summary of the differences of the scale readings.  The smaller the
better. The direct case is pretty poor except for 160m and 6m.

 JMB   Direct4to1  1to1
Band   Diff   DiffDiffDiff
160X  6   7   5
80 3  20  3   1
40 6  23  12 18
30-3  65  3   8
20 3  11  3   2
17 2  33  17  7
15 1  16  4   4
12 0  11  1   1
10 0  25  3   3
6   X  0   2   3


73,

John W2XS



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Re: [Elecraft] Twin Lead feedline

[Joe-aa4nn]

I have put 300 watts from a single 813
grounded grid amp into a doublet made
using 300 ohm twin lead.  No problem.
de Joe, aa4nn

- Original Message - 
From: Thom LaCosta [EMAIL PROTECTED]

To: Elecraft@mailman.qth.net
Sent: Tuesday, August 14, 2007 7:26 AM
Subject: [Elecraft] Twin Lead feedline



It's been years since I melted 300 ohm twin lead...

Can I use it for a 44 foot each side of center doublet at 100 watts out? 
I can't find any other open wire feedline locally, and I need to get 
something up in the airI keep on walking into the slinky that runs 
down my hallway.


I'm thinking at 5 watts it will pass...just not sure what will happen at 
100 watts.


Thanks

73 k3hrn
Thom,EIEIO
Email, Internet, Electronic Information Officer

www.baltimorehon.com/Home of the Baltimore Lexicon
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Re: [Elecraft] Twin Lead feedline

[Robert Tellefsen]

Thom
There are various grades of 300 ohm twinlead.
Some are very cheap and have pretty skimpy
conductors.  Some are good quality.  There is/was
at least one version that was suitable for transmitting
(power level not stated that I can recall).  If you
have some of the good quality stuff, you can probably
do 100w just fine.  I'd watch out for the skimpy stuff,
though.
Good luck and 73
Bob N6WG

- Original Message -
From: Thom LaCosta [EMAIL PROTECTED]
To: Elecraft@mailman.qth.net
Sent: Tuesday, August 14, 2007 4:26 AM
Subject: [Elecraft] Twin Lead feedline


 It's been years since I melted 300 ohm twin lead...

 Can I use it for a 44 foot each side of center doublet at 100 watts out?
I
 can't find any other open wire feedline locally, and I need to get
something up
 in the airI keep on walking into the slinky that runs down my hallway.

 I'm thinking at 5 watts it will pass...just not sure what will happen at
100
 watts.

 Thanks

 73 k3hrn
 Thom,EIEIO
 Email, Internet, Electronic Information Officer

 www.baltimorehon.com/Home of the Baltimore Lexicon
 www.tlchost.net/hosting/ Web Hosting as low as 3.49/month
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Re: [Elecraft] Twin Lead feedline

[Jozef Hand-Boniakowski]

I have been using TruValue twin lead at $14/100 feet for the past 4 
years on both my G5RV and my 40 meter loop.  Works just fine.  Best 
bargain around.  Since I only need 40 feet on either antenna, if it goes 
bad, I just use the other half  of what is left with some to spare.


Jozef WB2MIC

PS.  The antenna wire is leftover electric fence wire now over 22 years 
old.   Cost per antenna per year is quite low.  :)


Robert Tellefsen wrote:

Thom
There are various grades of 300 ohm twinlead.
Some are very cheap and have pretty skimpy
conductors.  Some are good quality.  There is/was
at least one version that was suitable for transmitting
(power level not stated that I can recall).  If you
have some of the good quality stuff, you can probably
do 100w just fine.  I'd watch out for the skimpy stuff,
though.
Good luck and 73
Bob N6WG

- Original Message -
From: Thom LaCosta [EMAIL PROTECTED]
To: Elecraft@mailman.qth.net
Sent: Tuesday, August 14, 2007 4:26 AM
Subject: [Elecraft] Twin Lead feedline


  

It's been years since I melted 300 ohm twin lead...

Can I use it for a 44 foot each side of center doublet at 100 watts out?


I
  

can't find any other open wire feedline locally, and I need to get


something up
  

in the airI keep on walking into the slinky that runs down my hallway.

I'm thinking at 5 watts it will pass...just not sure what will happen at


100
  

watts.

Thanks

73 k3hrn
Thom,EIEIO
Email, Internet, Electronic Information Officer

www.baltimorehon.com/Home of the Baltimore Lexicon
www.tlchost.net/hosting/ Web Hosting as low as 3.49/month
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Re: [Elecraft] Twin Lead feedline

[David Cutter]

I've just re-read your question.  So, the twin lead is not for the feeder, 
it's for the arms of the doublet, or possibly both.  I presume to widen the 
frequency response.  There are some interesting ideas for using ribbon as 
antennas.


If it's the pale pink variety, the only thing I would advise is to make sure 
you water-proof the cut ends because it will drink water by capillary action 
and rapidly rot the copper inside.  This happened to me many years ago.  If 
it's the black ladder line, I would say it is quite heavy compared to single 
wires.


Otherwise I see no particular problems.

David
G3UNA


- Original Message - 
From: Jozef Hand-Boniakowski [EMAIL PROTECTED]

To: Robert Tellefsen [EMAIL PROTECTED]
Cc: Elecraft@mailman.qth.net
Sent: Tuesday, August 14, 2007 5:02 PM
Subject: Re: [Elecraft] Twin Lead feedline


I have been using TruValue twin lead at $14/100 feet for the past 4 years 
on both my G5RV and my 40 meter loop.  Works just fine.  Best bargain 
around.  Since I only need 40 feet on either antenna, if it goes bad, I 
just use the other half  of what is left with some to spare.


Jozef WB2MIC

PS.  The antenna wire is leftover electric fence wire now over 22 years 
old.   Cost per antenna per year is quite low.  :)


Robert Tellefsen wrote:

Thom
There are various grades of 300 ohm twinlead.
Some are very cheap and have pretty skimpy
conductors.  Some are good quality.  There is/was
at least one version that was suitable for transmitting
(power level not stated that I can recall).  If you
have some of the good quality stuff, you can probably
do 100w just fine.  I'd watch out for the skimpy stuff,
though.
Good luck and 73
Bob N6WG

- Original Message -
From: Thom LaCosta [EMAIL PROTECTED]
To: Elecraft@mailman.qth.net
Sent: Tuesday, August 14, 2007 4:26 AM
Subject: [Elecraft] Twin Lead feedline




It's been years since I melted 300 ohm twin lead...

Can I use it for a 44 foot each side of center doublet at 100 watts out?


I


can't find any other open wire feedline locally, and I need to get


something up

in the airI keep on walking into the slinky that runs down my 
hallway.


I'm thinking at 5 watts it will pass...just not sure what will happen at


100


watts.

Thanks

73 k3hrn
Thom,EIEIO
Email, Internet, Electronic Information Officer

www.baltimorehon.com/Home of the Baltimore Lexicon
www.tlchost.net/hosting/ Web Hosting as low as 
3.49/month

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