Re: [Elecraft] When to use the preamps on the KX2/KX3 vs. K3/K3S

[na5n]

Wayne Burdick writes:

If the signals exceed a certain threshold, firmware will automatically  
turn off the preamp.


I generally operate in a fairly low noise environment and little strong  
signal interference.  Still, it is nice to learn the KX2 has such  
safeguards built in, especially since I plan on using mine at a 2 or 3  
station FD operation shortly and been wondering about what effect the SSB  
QRO station next to me will have.  I feel better now.


Another case is what we call “HF Pack Meeting Mode,” where two or more  
pedestrian mobile operators get their whips crossed :)


What?  No Crossed whip anti-overload vectorized buffer disrupter sensor?
:-)

72, Paul NA5N
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Re: [Elecraft] KPA500 cooling and efficiency

[K9MA]

On 5/21/2018 23:18, ANDY DURBIN wrote:

My KPA500 seems horribly inefficient when compared to my TS-590S running a similar power 
output.  The data for the heating test showed a PA efficiency of 23%, far short of the 
"approximately 50%" stated in the specification.


That's perfectly normal at that low power output.  The 50% spec is at 
full output.  If you ran your TS-590S at 20 W output, you would probably 
see about the same low efficiency.


73,

Scott K9MA

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[Elecraft] KPA500 cooling and efficiency

[ANDY DURBIN]

Bob,


I have made no changes to the cooling of my KPA500.  I also have no idea to 
what extent the designers of the KPA500 studied the thermodynamics of the 
design.   I have, however, been surprised at how quickly it heats up.I 
abandoned a heating test with the amplifier only producing 100 W output when 
the PA temperature reached 70 deg C after only 1 minute 45 seconds.  At that 
point the temperature was close to asymptotic and fan speed was 5 so it may not 
have gone much higher.


My KPA500 seems horribly inefficient when compared to my TS-590S running a 
similar power output.  The data for the heating test showed a PA efficiency of 
23%, far short of the "approximately 50%" stated in the specification.


I'm willing to share my test data but I know of no means to post it on this 
stone age "reflector".


73,

Andy k3wyc



From: Bob McGraw K4TAX 
Sent: Monday, May 21, 2018 6:57 PM
To: ANDY DURBIN
Subject: Re: [Elecraft] KPA1500 fan speeds and fan noise

Andy:

There are basically two types of radial blade fans and specific
application for each one.   Those that "blow" and those that "suck".
There is a difference in the design of the fan blades and the
application for a specific fan.   Also some are designed to have "air
over the motor".  This is a point affecting motor life and bearing
lubrication.

Those that "blow" are designed to pressurize a box or enclosure to a
specific  pressure measured in inches or millibars of H²O. Reducing the
air exhaust area or restricting air exhaust flow, thus increasing
internal pressure, can cause a blade stall.  This actually reduces the
amount of air measured in CFM that a given fan can deliver.

The other type  of fan, those that "suck" are designed to exhaust air
from a box or enclosure to a specific value measured in inches or
millibars of H²0. There is always some amount of restriction to
airflow entering, usually being contributed by the obstruction i.e. air
vents,  to air entering the box.  The perforated air vent on top of the
KPA500 as an example.

While I agree that increased airflow is beneficial to keeping
electronics cool, one must assure that added cooling efforts do not
create a vortex in the given area to be cooled.   This could cause a
void of air movement and thus reduced cooling.The KPA500 {I can't
speak for the KPA1500} are surely engineered and evaluated {brick on the
key}  to work within design limits of the solid state devices along with
cooling other components.In some cases, ones added cooling efforts
which may actually cause a partial blade stall, same as the stall effect
of an airplane wing, and thus cooling is actually reduced and, in many
cases.  In some instances, overall fan noise being increased.

Take care in the application of added cooling efforts.

I run my KPA500 with the FAN CTL at Normal.   It will step through all 6
levels as needed, otherwise it is off.I find no reason for it to run
all of the time at the lowest speed. Depending on mode and length of
transmission, I find the fan comes on and will ramp up as needed.
I've not seen any reported temperature above 65ºC with a heat sink upper
limit of 90ºC.

73

Bob, K4TAX



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[Elecraft] KPA1500 ATU

[K9MA]

After "training" the ATU across part of the band and, I think, setting 
up the K3 so it should track, I notice some strange behavior.  As I tune 
to a different segment of the band, and stop, there's a delay or a 
second or so before the ATU relays switch. Other times, even though it's 
already been tuned to the new frequency, it doesn't switch until 
transmission starts which, of course, garbles the first character.  Am I 
doing something wrong, or have others notice this behavior?  I assumed 
that once the ATU has been tuned to each band segment, it would switch 
as soon as the K3 was tuned to a new segment (if necessary), so it would 
be ready to go when transmission starts.


73,

Scott K9MA

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k...@sdellington.us

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[Elecraft] When to use the preamps on the KX2/KX3 vs. K3/K3S

[Wayne Burdick]

Occasionally we have a KX2 or KX3 user claim their rig has low receive 
sensitivity. Often this is simply because the preamp is turned off. 

These users may be used to superhet receivers like the one in the K3/K3S, where 
preamp-off sensitivity (MDS) is typically in the -130 dBm range (or better). 
The preamp is rarely needed below 15 meters on these rigs.

In contrast, the KX2 and KX3 are quadrature downconversion designs that have 
the A-to-D converter farther up the signal chain. Even very high-performance 
ADCs have quite high noise figures, resulting in preamp-off MDS of around -120 
dBm. So the preamp is needed more often. Typically, the preamp on the KX2 or 
KX3 should be used on 20 m and up unless extremely strong interference is 
present, or if you have a very high ambient noise level. 

Related notes: 

All Elecraft transceivers keep tabs on how strong incoming signals are. If the 
signals exceed a certain threshold, firmware will automatically turn off the 
preamp. (This is preceded by a “HI SIG” warning on the display.)

If signals are so high they might cause damage to the front end--say, a watt or 
two as measured at the antenna jack--firmware takes the further step of 
temporarily turning off all of the low-pass filters. This drops the signal 
level at the receiver’s front end by some 60-80 dB. The actual level of this 
“carrier operated relay” function is configurable in some cases (COR LVL menu 
entry). 

A typical case of this would be at field day, where antennas for two different 
stations are inadvertently placed extremely close together and one or both are 
used at high transmit power. The cure is to move them farther apart. The radio 
will then reenable the normal signal path.

Another case is what we call “HF Pack Meeting Mode,” where two or more 
pedestrian mobile operators get their whips crossed :)

73,
Wayne
N6KR

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Re: [Elecraft] setting up k3s to be used in conjunction with K3/0

[David Shoaf]

Here's the  Quick Start Guide from Remotehams.com
   for the K3/0 Mini.  Will
that do?

Cheers,

David



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[Elecraft] setting up k3s to be used in conjunction with K3/0

[Pete Block]

Hi,

This is my first post to this group so if I do something wrong please go
easy on me.

I have a K3s set up at home and I carry a KX3 with me when I travel.

I'll be leaving in just over a week for an extended road trip.

I'd like to get a K3/0 and take it with me to talk to people from my home
qth.

I've downloaded the remote hams server software to my PC and I'd like a blow
by blow outline

of how to connect the K3s to the PC so I can then set up the K3/0 to my
laptop when I get it.

I'll probably take delivery on the K3/0 in a couple of days.

Thanks for any help.

Pete

W2MGE

 

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[Elecraft] OT: old ARRL RA Handbook info

[Mike Maloney]

Thanks to the many of you who replied.   Got wanted info pretty quickly.   
Amazing how many are holding on to old RA handbooks.  
73,
Mike  AC5P
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Re: [Elecraft] KPS1500 fan noises

[Bob McGraw K4TAX]

There are basically two types of radial blade fans and specific 
application for each one.   Those that "blow" and those that "suck".  
There is a difference in the design of the fan blades and the 
application for a specific fan.   Also some are designed to have "air 
over the motor".  This is a point affecting motor life and bearing 
lubrication.


Those that "blow" are designed to pressurize a box or enclosure to a 
specific  pressure measured in inches or millibars of H²O. Reducing the 
air exhaust area or restricting air exhaust flow, thus increasing 
internal pressure, can cause a blade stall.  This actually reduces the 
amount of air measured in CFM that a given fan can deliver.


The other type  of fan, those that "suck" are designed to exhaust air 
from a box or enclosure to a specific value measured in inches or 
millibars of H²0. There is always some amount of restriction to 
airflow entering, usually being contributed by the obstruction i.e. air 
vents,  to air entering the box.  The perforated air vent on top of the 
KPA500 as an example.


While I agree that increased airflow is beneficial to keeping 
electronics cool, one must assure that added cooling efforts do not 
create a vortex in the given area to be cooled.   This could cause a 
void of air movement and thus reduced cooling.    The KPA500 {I can't 
speak for the KPA1500} are surely engineered and evaluated {brick on the 
key}  to work within design limits of the solid state devices along with 
cooling other components.    In some cases, ones added cooling efforts 
which may actually cause a partial blade stall, same as the stall effect 
of an airplane wing, and thus cooling is actually reduced and, in many 
cases.  In some instances, overall fan noise being increased.


Take care in the application of added cooling efforts.

I run my KPA500 with the FAN CTL at Normal.   It will step through all 6 
levels as needed, otherwise it is off.    I find no reason for it to run 
all of the time at the lowest speed. Depending on mode and length of 
transmission, I find the fan comes on and will ramp up as needed.    
I've not seen any reported temperature above 65ºC with a heat sink upper 
limit of 90ºC.


73

Bob, K4TAX



On 5/21/2018 2:32 PM, Roy Koeppe wrote:


"Do the KPA1500 fans push air into the box? If so, why doesn't the 
KPA500 fan do that. If the KPA1500 fans pull out of the box why would 
it be appropriate to use an additional fan that opposes this airflow?"


Yes, they do...which is also opposite of airflow in K3s. The idea of 
the additional fans is that they are much more quiet than the built 
ins, even when they are on speed #1 . And they prevent the built ins 
from running so much or not at all. Simpleminded, I admit.


Roy   K6XK

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Re: [Elecraft] Closed threads

[Chris Hallinan]

Wes,

I was going to say something but decided to keep my mouth shut.  It's about
time someone did.

Thank you.


73 de K1AY

On Sun, May 20, 2018 at 5:51 PM, Wes Stewart  wrote:

> I just love it when Eric declares a thread closed and ten guys write to
> say "Thank you" or "I was going to say something but kept my mouth shut" or
> "It's about time", etc...
>
> Wes  N7WS
>
> ps. This thread is closed.:-)
>
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Re: [Elecraft] K3 for sale

[DBB]

Is your K3 still available?

Tnx.



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Re: [Elecraft] KPA1500 fan noises

[Roy Koeppe]

"The benefit to putting fans in back blowing through the stock
screen/fans is that you get the slight added benefit of over-pressuring
the chassis which tends to keep the chassis interior cleaner. Assuming
adequate rear spacing, you can hide the fans a bit more"

Yes. and the ultimate is placing them remotely in the closet with a clothes 
dryer hose leading to that plenum sitting at the back air intake coupling. 
Care must be taken so as not to ever restrict air intake to the internal 
fans when they're running at max speed.


Roy


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Re: [Elecraft] kpa1500 new issue

[Bill Stravinsky via Elecraft]

 Well, I just spoke with Elecraft and it appears this problem was one they had 
run across in early engineering.  I sent them the config file which might have 
some indicatorsthey can look at and make some determinations.  But if it turns 
out to be what the engineer said it might, there might be a fix that is needed 
to cure this if the temp swing istoo much.
Film at eleven.
BillK3WJV

On Monday, May 21, 2018, 12:58:37 AM EDT, Bill Stravinsky via Elecraft 
 wrote:  
 
 In the last few days I have made about 21 Qso's with the new amp casually and 
about 75 Q's in a few contests over the weekend.  The first night I had a 
problem that seemedto disappear.  It only happened on 40mtrs.  I was xmitting 
and the power dropped like I went into stby but no indications on the front 
panel other than the power LED's showinga power drop.  I chalked it up to maybe 
not having things setup right as it hasn't happened again.
But tonite I was making some 40 mtr Q's and everything looked normal except the 
temp was jumping from 6 to 8 degrees low, meaning the temp was climbing 
normally then itwould fluctuate rapidly down about 6 degrees.  If I stopped 
xmitting the temp was stabile but xmitting it would jump down and back up 
quickly.  And now as I'm typing this postthe temp has gone down to normal but 
the same thing is now happening.  Every time I xmit the temp jumps down about 6 
degrees and fluctuates back and forth.
I checked on 20 mtrs and it doesn't happen there so either I've got some rf 
floating around on 40 or there is a problem in the amp.  I ran the power down 
and it happens all theway down to about 500 watts out but only fluctuates about 
4 degrees.  Just checked on 80 and its OK there.  So will look into this tmrw 
some more.
BillK3WJV
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Re: [Elecraft] KPS1500 fan noises

[Clay Autery]

Roy, contrary to what the other guy said, that is a perfectly logical 
supplement to the OE cooling system.  ANYTHING that reduces the pressure 
at the exit venting will improve airflow over the heatsink.
Increase inlet and exit free area and/or increase inlet pressure or 
reduce outlet pressure.  all will increase flow volume.


Alternatively/additionally, the industrious owner might also consider a 
custom duct in the back that would provide for adding multiple 120mm or 
140mm high-quality fans set to blow air IN.  I prefer Noctua fans these 
days.  They are quiet, come with anti-vibration mounts built in, and 
there are full anti-vibe gaskets available on some models that prevent 
flow short circuits.  They also come in 3-pin or 4-pin models.  3-pin 
models can generally be set to run at full speed or at 1 or 2 slower 
speeds.  The trick solution would be to use 4-wire fans and your own 
feedback loop controller to adjust the speed dynamically. albeit, 
you need to test and modify any of the ready-built controllers to make 
sure you aren't broadcasting RF birdies with the PWM.


The benefit to putting fans in back blowing through the stock 
screen/fans is that you get the slight added benefit of over-pressuring 
the chassis which tends to keep the chassis interior cleaner. Assuming 
adequate rear spacing, you can hide the fans a bit more


I could go on...  I love thermal control stuff...  I'd be interested to 
see the numbers on how much power/heat is dissipated at 1500W key down...


73,

__
Clay Autery, KY5G
(318) 518-1389

On 05/21/18 14:32, Roy Koeppe wrote:


"Do the KPA1500 fans push air into the box? If so, why doesn't the 
KPA500 fan do that. If the KPA1500 fans pull out of the box why would 
it be appropriate to use an additional fan that opposes this airflow?"


Yes, they do...which is also opposite of airflow in K3s. The idea of 
the additional fans is that they are much more quiet than the built 
ins, even when they are on speed #1 . And they prevent the built ins 
from running so much or not at all. Simpleminded, I admit.


Roy   K6XK


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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Bill Stravinsky via Elecraft]

 Feel free to do that with your kpa1500.  While you're at it test how long it 
takes to reach 60C with and without the modified fan system.I'm comfy with 
hearing the fans come on and I even set the fan speed to 1 or 2 if I'm in a 
contest mode.  I don't think there's a thing astoo much cooling for a solid 
state amp running 1500 watts.  The brief time I've played with mine it doesn't 
take too long to get to 60Cif you xmit enough.
Good luck.
BillK3WJV

On Monday, May 21, 2018, 5:11:01 PM EDT, hawley, charles j jr 
 wrote:  
 
 Seems like if the internal fans don't go on, that means the fan on the top is 
cooling the amp.

Chuck Hawley
 c-haw...@illinois.edu

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles

From: elecraft-boun...@mailman.qth.net [elecraft-boun...@mailman.qth.net] on 
behalf of Bill Stravinsky via Elecraft [elecraft@mailman.qth.net]
Sent: Monday, May 21, 2018 8:01 AM
To: Elecraft Reflector
Subject: Re: [Elecraft] KPA1500 fan speeds and fan noise

 That doesn't move any air across the heat sink or solid state devices that 
need the air.  The air that comes out of those vents starts at the fans in the 
rear.
BillK3WJV

    On Monday, May 21, 2018, 6:07:22 AM EDT, Roy Koeppe  wrote:

 All,

My solution is two 4.5-inch, 48-volt dc muffin fans sitting on half-inch
tall rubber feet covering the top exhaust vent on amp. They are running on a
19-volt supply at a slow but effective cooling speed and are very quiet
(drawing air upward). During normal CW rag chewing the main fans do not come
on -- a vast improvement for a few bucks. When you go portable, just leave
'em home.

73,    Roy        K6XK












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Re: [Elecraft] KPA1500 fan speeds and fan noise

[hawley, charles j jr]

Seems like if the internal fans don't go on, that means the fan on the top is 
cooling the amp.

Chuck Hawley
 c-haw...@illinois.edu

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles

From: elecraft-boun...@mailman.qth.net [elecraft-boun...@mailman.qth.net] on 
behalf of Bill Stravinsky via Elecraft [elecraft@mailman.qth.net]
Sent: Monday, May 21, 2018 8:01 AM
To: Elecraft Reflector
Subject: Re: [Elecraft] KPA1500 fan speeds and fan noise

 That doesn't move any air across the heat sink or solid state devices that 
need the air.  The air that comes out of those vents starts at the fans in the 
rear.
BillK3WJV

On Monday, May 21, 2018, 6:07:22 AM EDT, Roy Koeppe  wrote:

 All,

My solution is two 4.5-inch, 48-volt dc muffin fans sitting on half-inch
tall rubber feet covering the top exhaust vent on amp. They are running on a
19-volt supply at a slow but effective cooling speed and are very quiet
(drawing air upward). During normal CW rag chewing the main fans do not come
on -- a vast improvement for a few bucks. When you go portable, just leave
'em home.

73,RoyK6XK












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[Elecraft] KPA1500, First Impressions

[K9MA]

So far, all looks good.  My only concern is that the ATU doesn't always 
find a good match, even when the antenna is below 2:1. With the default 
"stop" threshold set to 1.2, it often stops at 1.6:1 or greater.  A 
second tuning sometime helps a bit. Increasing tune power to 20W didn't 
help much. It seems the ATU ought to be able to do better than that with 
a 2:1 load.  Has anyone else noticed this?


That said, integration with the K3 seems to have gone without a hitch.

73,

Scott K9MA

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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Walter Underwood]

> On May 21, 2018, at 1:56 PM, Bill Stravinsky via Elecraft 
>  wrote:
> 
> If you are going to depend on those 2 fans sucking hot air out of the amp 
> instead of using the internal fans that push it where it needs to go, I think 
> you arepulling hot air out of the amp and that hot air has already done its 
> damage.
> BillK3WJV


And pulling cool air in, probably through those big holes with fans in them, 
right where it needs to go. And if the amp gets hot, the built-in fans come on.

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

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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Bill Stravinsky via Elecraft]

 If you are going to depend on those 2 fans sucking hot air out of the amp 
instead of using the internal fans that push it where it needs to go, I think 
you arepulling hot air out of the amp and that hot air has already done its 
damage.
BillK3WJV

On Monday, May 21, 2018, 3:29:29 PM EDT, Roy Koeppe  wrote:  
 
 Yes it does, normally air flow is from rear to top. The fans placed over the 
exhaust vent on top create a partial vacuum, drawing in air through the idle 
(or running) fans on the rear apron and out the top just like when the 
regular fans are doing that job.

Roy    K6XK


"That doesn't move any air across the heat sink or solid state devices that 
need the air.  The air that comes out of those vents starts at the fans in 
the rear."
BillK3WJV

    On Monday, May 21, 2018, 6:07:22 AM EDT, Roy Koeppe  
wrote:

All,

My solution is two 4.5-inch, 48-volt dc muffin fans sitting on half-inch
tall rubber feet covering the top exhaust vent on amp. They are running on a
19-volt supply at a slow but effective cooling speed and are very quiet
(drawing air upward). During normal CW rag chewing the main fans do not come
on -- a vast improvement for a few bucks. When you go portable, just leave
'em home.

73,    Roy        K6XK



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[Elecraft] OT: old ARRL RA handbook

[Mike Maloney]

Would anyone reading per chance have a 1960 or '61, '62 Radio Amateurs Handbook 
handy?Reply direct off list.  Thanks
Mike  AC5P
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Re: [Elecraft] KPS1500 fan noises

[Roy Koeppe]

"Do the KPA1500 fans push air into the box? If so, why doesn't the KPA500 
fan do that. If the KPA1500 fans pull out of the box why would it be 
appropriate to use an additional fan that opposes this airflow?"


Yes, they do...which is also opposite of airflow in K3s. The idea of the 
additional fans is that they are much more quiet than the built ins, even 
when they are on speed #1 . And they prevent the built ins from running so 
much or not at all. Simpleminded, I admit.


Roy   K6XK 



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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Roy Koeppe]

Yes it does, normally air flow is from rear to top. The fans placed over the 
exhaust vent on top create a partial vacuum, drawing in air through the idle 
(or running) fans on the rear apron and out the top just like when the 
regular fans are doing that job.


RoyK6XK


"That doesn't move any air across the heat sink or solid state devices that 
need the air.  The air that comes out of those vents starts at the fans in 
the rear."

BillK3WJV

   On Monday, May 21, 2018, 6:07:22 AM EDT, Roy Koeppe  
wrote:


All,

My solution is two 4.5-inch, 48-volt dc muffin fans sitting on half-inch
tall rubber feet covering the top exhaust vent on amp. They are running on a
19-volt supply at a slow but effective cooling speed and are very quiet
(drawing air upward). During normal CW rag chewing the main fans do not come
on -- a vast improvement for a few bucks. When you go portable, just leave
'em home.

73,RoyK6XK



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[Elecraft] test

[Fred Cady]

test message
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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Ed Gray W0SD]

I have a KPA-1500  #171 and when I set the fans at 1 the air is being 
pulled from the back by only the middle fan on  the back. The air is 
exiting out the top cover, front, right.  This exit area is just a 
little over 5" x 8".  I feel a good deal of air coming out the top 
evenly distributed over the 5" x 8" area.


Set at position 2, 3, 4 and 5 all three fans run and the fan speed is 
increased with each setting.  2 is IMHO is not very noisy, 3 is more 
noise than I like if ran continuously. Sporadically would be OK assuming 
it would not be needed a lot. 4 and especially 5 are noisy.  However I 
would think you would only need 4 or 5 with lots of TX in RTTY or WSJT 
modes so one would not need to be concerned about mic pick up however I 
will say 4 and 5 are not pleasant to listen to.  More to be learned by 
me but I suspect letting the fan be regulated by the temperature rather 
than a fixed setting may be the way to go for lots of TX in RTTY or WSJT.


Anyway the air comes in the back and goes out the top cover on the KPA-1500.

Ed W0SD



On 5/21/2018 9:13 AM, ANDY DURBIN wrote:

>From the KPA500 kit build manual:

"If airflow arrows are visible on the fan housing, they will show that air will be 
blown out of the back of the KPA500."


It was a bit surprising to me that the KPA500 fan airflow is the opposite of 
natural convective flow but I accepted that was the intended design.  My KPA500 
fan does pull air in the top and exhaust it out of the back.


"They are running on a 19-volt supply at a slow but effective cooling speed and are 
very quiet (drawing air upward)."


Do the KPA1500 fans push air into the box? If so, why doesn't the KPA500 fan do 
that. If the KPA1500 fans pull out of the box why would it be appropriate to 
use an additional fan that opposes this airflow?


73,

Andy k3wyc
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[Elecraft] KPA1500 fan speeds and fan noise

[ANDY DURBIN]

>From the KPA500 kit build manual:

"If airflow arrows are visible on the fan housing, they will show that air will 
be blown out of the back of the KPA500."


It was a bit surprising to me that the KPA500 fan airflow is the opposite of 
natural convective flow but I accepted that was the intended design.  My KPA500 
fan does pull air in the top and exhaust it out of the back.


"They are running on a 19-volt supply at a slow but effective cooling speed and 
are very quiet (drawing air upward)."


Do the KPA1500 fans push air into the box? If so, why doesn't the KPA500 fan do 
that. If the KPA1500 fans pull out of the box why would it be appropriate to 
use an additional fan that opposes this airflow?


73,

Andy k3wyc
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[Elecraft] Test 2018-05-21

[John Gibson]

This is 2nd test message. Please ignore.

73,

John, no8v

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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Bill Stravinsky via Elecraft]

 That doesn't move any air across the heat sink or solid state devices that 
need the air.  The air that comes out of those vents starts at the fans in the 
rear.
BillK3WJV

On Monday, May 21, 2018, 6:07:22 AM EDT, Roy Koeppe  wrote:  
 
 All,

My solution is two 4.5-inch, 48-volt dc muffin fans sitting on half-inch 
tall rubber feet covering the top exhaust vent on amp. They are running on a 
19-volt supply at a slow but effective cooling speed and are very quiet 
(drawing air upward). During normal CW rag chewing the main fans do not come 
on -- a vast improvement for a few bucks. When you go portable, just leave 
'em home.

73,    Roy        K6XK












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Re: [Elecraft] [K2] Using the K2 above 29 MHz

[Steve Kavanagh via Elecraft]

I made some measurements on my K2/K60XV.  It seems the bandpass filter does cut 
off just above 28.8 MHz and the available 1 mW output from the K60XV drops 
markedly starting around 29 MHz. It would not be practical to use this output 
unless the bandpass filter were retuned.  

At the QRP antenna jack, using WSJT (and therefore presumably SSB) the power 
remains constant (when set for 2 watts) up to at least 29.4, so it seems the 
power control algorithm is doing its job.  On CW, however, when raising the 
frequency the power drops.  When starting at 29.4 MHz and going down, the power 
goes up well above 2 W.  It can be reset to 2 W by moving the power knob off 
the 2 watt setting and back again.  This isn't very practical in real 
operation, so once again, the conclusion is that to operate above 29 MHz the 
bandpass filter would need to be retuned.

73,
Steve VE3SMA
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Re: [Elecraft] KPA1500 fan speeds and fan noise

[Roy Koeppe]

All,

My solution is two 4.5-inch, 48-volt dc muffin fans sitting on half-inch 
tall rubber feet covering the top exhaust vent on amp. They are running on a 
19-volt supply at a slow but effective cooling speed and are very quiet 
(drawing air upward). During normal CW rag chewing the main fans do not come 
on -- a vast improvement for a few bucks. When you go portable, just leave 
'em home.


73,Roy K6XK












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Re: [Elecraft] K4

[Petr, OK1RP/M0SIS]

Hi,

definitely less birdies (impossible by tech) and less misbehavior ...it is
enough for me.

73 - Petr, OK1RP




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http://ok1rp.blogspot.com
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Re: [Elecraft] K2 - Issue after installing K60XV

[paulb]

possible long shot  check status of D19  Alignment and Test 


cheers




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