David,
True but IIRC I was replying to a message where he said the SWR was flat
through 6m. Usually, somewhere between 20m and 6m, receive losses do count.
Ken WA8JXM
On 1/14/2024 4:33 PM, David Woolley wrote:
The receive part of the penalty, from a lossy antenna, only applies if
the
The receive part of the penalty, from a lossy antenna, only applies if
the dominant noise source is after the point of attenuation. That's not
generally true at HF.
(I wonder if, at microwave frequencies, it is possible to use
circulators and isolators to put passive losses in on only the
If you were putting 200 watts into it on FT8 that's almost three times
the manufacturers rating and you're lucky you didn't fry it.
Dave AB7E
On 1/14/2024 1:18 PM, Michael Reynolds, NO6O wrote:
Actually, I was only putting around 200 into the antenna, and it's
doing fine. I've been
Actually, I was only putting around 200 into the antenna, and it's doing
fine. I've been continuing to make digital contacts without the amp and
tuner. The antenna works great for me. I reached 50 countries during
the past few weeks of testing. Fortunately, I fully understand what was
Fully agree. The specs for the CHA-250B say a maximum of 75 watts for
digital modes ... i.e., continuous duty modes. That pretty much says
what the actual heat dissipation capability is. If he was trying to put
500 watts into his antenna in almost any mode, it is probably toast ...
The Cha250 b is NOT an antenna capable of greater than 100 watts for any
length of time. It is a 5:1 unun hooked to a 23 foot aluminum radiator. It
needs to be 30 feet in the air and if that happens it will function like a
vertical OCFD. Still it is only good for 100 watts. When running a tuner
On 1/13/2024 2:02 PM, email wrote:
With the K4 power (drive) low enough, the amp can make 200W. Maybe not
efficiently.
I regularly reduce drive from K3 or K4 to big amp to run 100W in NAQP,
and on 60M, and 200W on 30M. I do that because I run the K3 and K4 for
two-radio contesting from a
The military isn't chasing DX or contesting ... They need enough
radiation for adequate operation in their networks. In the example, a
resistor in the folded dipole gives them that, they don't care about the
3dB, and a much easier radio system to set up. Little different for us
"Amateurs."
Unless its something like a log periodic, I think anything with those
frequency/SWR specs can only do it with high resistive losses. It
reminds me of the HF dipole B makes for the military: it is designed
to appear to have a low SWR by having 3 db of resistive losses. The
military
Bob, K4TAX
On 1/13/2024 3:58 PM, elecraft-requ...@mailman.qth.net wrote:
Message: 5
Date: Fri, 12 Jan 2024 23:28:09 -0600
From: "Michael Reynolds, NO6O"
To:elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT 500 Loses Match
Message-ID:
Content-Type: text/plain; charset=UTF-8; for
Check all of your connections such as PL-259 and SO-239. I once had the same
problem with a dipole antenna and a loose shield wire would disconnect and put
my SWR >9. You could also have a bad kink in your coax cable.
Good Luck
Sent with Proton Mail secure email.
On Friday, January 12th,
With the K4 power (drive) low enough, the amp can make 200W. Maybe not
efficiently. (yes, 200W is only 3db more than 100W) If FT8 RX level
at -24, then 3db may be important ??
steve WB3LGC
On 1/12/24 7:52 PM, Ken WA8JXM wrote:
Why do you have the amplifier running? 30m is as restricted
t;
> Michael
> NO6O
>
>
> On 2024-01-12 10:36 PM, Bill Johnson wrote:
>> Good advice
>>
>> Bill
>> K9YEQ
>>
>> From: elecraft-boun...@mailman.qth.net on
>> behalf of Ken WA8JXM
>> Sent: Friday, Janua
The C HA-50HD is rated for 250 W SSB or 75 W for digital modes. It gets a flat
SWR with resistive losses in the transformer. That is why the transformer has
heat sink fins. A KPA500 is almost certainly overheating the transformer and
causing failures. I would back off the power to match the
The only thing that has a flat 1:1 SWR from 80m to 6m is a good quality
dummy load.
Dave AB7E
On 1/12/2024 10:28 PM, Michael Reynolds, NO6O wrote:
Greetings,
I joined this list today, after sending a message to Elecraft support,
describing a similar problem. I have an Icom IC-7610,
I have a CHA-250B antenna, but it is not currently up. This antenna is only
rated for 250W SSB which is probably 100W on CW or a digital mode. I think
this antenna has a matching network and at higher powers will saturate the
cores causing SWR to rise out of control. Same thing happens for me with
Your situation sounds like 1) something is heating up and changing value
or 2) something is arcing and changing value. Are you using a balun or
choke that is underrated?
Ken WA8JXM
On 1/13/2024 12:28 AM, Michael Reynolds, NO6O wrote:
Greetings,
I joined this list today, after sending a
From: elecraft-boun...@mailman.qth.net on behalf
of Ken WA8JXM
Sent: Friday, January 12, 2024 5:52:52 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT 500 Loses Match
It's possible that something is arcing and, of course changing the tuning.
Do you have the internal tuner in the K4
I just realized you said 30m. Why are you running the amplifier ("max
power") on 30m??
Dave AB7E
On 1/12/2024 2:46 PM, Paul Ecker wrote:
I am experiencing a new problem for me, with my KAT 500. So far I've
noticed this issue on 30M. I am using a dipole cut only for 30M with an SWR
of
Good advice
Bill
K9YEQ
From: elecraft-boun...@mailman.qth.net on
behalf of Ken WA8JXM
Sent: Friday, January 12, 2024 5:52:52 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT 500 Loses Match
It's possible that something is arcing and, of course
Thanks to all for the advice and suggestions. Will be out of pocket for a
day or so, but you have given me lots of areas to checkout and
troubleshoot. Will let you know what I find out.
73 Paul w2eck
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Elecraft mailing list
Home:
It's possible that something is arcing and, of course changing the tuning.
Do you have the internal tuner in the K4? If so, does it behave the
same way?
Why do you have the amplifier running? 30m is as restricted power band.
If you leave the amp and tuner out of the circuit and transmit
It sounds like a bad connection or arc-over in a connector, cable,
balun, etc. after the KAT500. I had a similar issue that drove me nuts
for weeks until I found a corroded solder connection in a balun at the
feedpoint of an antenna. It does not sound like an RFI issue.
73, Victor, 4X6GP
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That sounds EXACTLY like an arc over somewhere past your KAT500. Could
be a connector, the coax, the connection to the dipole, or any similar
spot, but my bet would be the connection to the connector or the
connector itself.
Dave AB7E
On 1/12/2024 2:46 PM, Paul Ecker wrote:
I am
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT 500 Loses Match
Ken
With the KAT connected to a dummy load on the 30M port, I don't see the
problem re-occur. The SWR measured outside prior to entering the box with a
polyphaser is low. So some type of problem is between the KAT
Ken
With the KAT connected to a dummy load on the 30M port, I don't see the
problem re-occur. The SWR measured outside prior to entering the box with a
polyphaser is low. So some type of problem is between the KAT and the
connection box outside??
73 & tnx for help
Paul w2eck
On Fri, Jan 12, 2024
On 1/12/2024 1:46 PM, Paul Ecker wrote:
Does this sound like a KAT 500 problem or maybe an RFI problem.
It sounds like a problem somewhere after the output of the power amp,
including all interconnecting cables, the feedline, and the antenna.
Common problems are loose connectors and/or
Paul,
Connect a dummy load in place of the antenna and repeat your testing.
This will eliminate the antenna as a possible source of RFI.
Report the results of your tests,
GL!
*Ken*
*WA2LBI*
On Fri, Jan 12, 2024 at 4:47 PM Paul Ecker wrote:
> I am experiencing a new problem for me, with
I am experiencing a new problem for me, with my KAT 500. So far I've
noticed this issue on 30M. I am using a dipole cut only for 30M with an SWR
of 1.2 to 1.3 max SWR across the band. I “trained the tuner” at 20khz
segments on 30M.
Setup is K4D, KAT 500 & KPA 500. Win 10 pc.
Running CW, I can
30 matches
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