"With the OPER light GREEN and slowly increasing the RF drive level to the amp,
there is a point where an internal relay 'click' can be heard, the 50-watt LED
on the top row of LEDs turns red and the FAULT light turns red."
All the KPA500 LED are single color. The 50 W LED is either lit green
"My KAT500 will no longer tune in AUTO mode on 20M and does not change to
prior stored settings in MAN mode. All other bands work as expected in
both modes. Any suggestions on where I should look first?"
Use the utility to check that KAT500 has tuned to your 20 m frequency. If it
has, then
You can re-post as many times as you like but this stone-age reflector will
discard any images you attempt to share.
One solution is the put the image file in drop box, or similar, and share the
link.
Andy, k3wyc
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Elecraft mailing
"The KAT serial port is MONO, not STEREO, as I (not so quickly) discovered"
The plug has to connect data in, data out, and ground. That requires 3
contacts which cannot be done with a mono plug!
The KAT500 PC DATA port uses a STEREO plug.
Andy, k3wyc
"My Winkeyer has settings for both lead and tail time, and so does N1MM+.
WSJT-X does not appear to have these variables."
WSJT-X has provision for changing the delay between assertion CAT PTT and onset
of audio (settings/advanced/miscellaneous). The delay between end of audio and
CAT PTT
I don't have the same equipment as you but I experienced a very similar problem
that I initially thought was caused by a problem with my KPA500.However,
when I looked at the output of my TS-590S with a scope and spectrum analyzer,
I found that it was emitting out of band spurii at the end
"Presumably it has some very sophisticated detection that can tell if a
frequency is in use?"
My auto trainer function is only used on 160 m and 80 m and only during the day
when I expect the bands to be dead and as confirmed by the panadapter. It
doesn't need a detection system any more
"I see some people are using HDSDR software - I did try installing that, but it
insists on using OmniRig v2, whereas my Logging program (Log4OM) and WSJT-X use
OmniRig v1.1 and I'm not sure I can make the swap to Omnirig 2."
I use an RSP with OmniRig 1.20 and HDSDR 2.76a. Support for OmniRig 1
"Do you have a K-Pod button programmed to do all this?"
No, it's code in an Arduino Mega 256 than sequences a couple of state machines.
One state machine controls putting KAT500 in full search tune, powering the
exciter, waiting for completion of auto tune, returning exciter to RX mode.
The
"One thing I forgot. The KAT500 should only be in AUTO mode when you’re
actually training it."
Training a KAT500 does not require it to be in AUTO mode. I NEVER put my
KAT500 in AUTO mode and I can auto train a complete band with one button push.
Andy, k3wyc
"AFAICR the manual says that if an AUX cable is connected between the KAT500
and the radio, the KAT500 will follow any frequency/band change and if a tuning
solution has already been stored for that frequency/band it will be employed
before the radio goes into TX. In other words, whilst the
"> How does your KAT500 know what frequency to use? Does it have a serial data
interface or does it depend only on the internal RF counter?
>
W7BRS> AUX cable between K3 to KAT-500 and KAT-500 to KPA-500. They are in
serial communication per Elecraft protcol(s), whatever those are.
> What
"Actual Results: The ATU-500 clicks between Bypass and MAN (by "clicks", I mean
only what I can infer from the behavior -- it is as if the ATU-500 is either
using the memory-based ATU settings of the previously tuned settings and
switching between that and what seems like a Bypass mode) -- the
I was running ver 1.21.10.8 and the edit threshold function appears to work
correctly.
I installed 1.23.9.8 and found all thresholds were blank (current values not
displayed) and could not be edited.
Utility ver 1.23.9.8 seems to be broken. I suggest running 1.21.10.8. Email
me if you don't
"Anyone interested in the current draw for Sleep and Off (but powered) states
could simply put a multimeter in the PSU lead. I would expect a difference in
current between Off and Sleep that would depend strongly on the number of
tuning relays that were active while sleeping. No relays are
"Off" and "sleep" are not the same states. Also "Off" is not the same state as
"not powered".
"PS Power on/off
GET format: PS;
SET/RESPONSE format: PS0; or PS1;
Turns the KAT500 ON (PS1;) or OFF (PS0;).
The KAT500’s microcontroller operates whenever DC power is applied. LEDs and
relays are off
"Scope traces for a typical KAT500 serial data interface can be found here -
https://www.dropbox.com/scl/fi/ypk0ks16rl03d55ugm4t9/KAT500-signal-levels.pdf?rlkey=7iahis4xp0jnua3c8s577cxjq=0;
The depicted voltage levels for KAT500 driving the KXUSB were not typical. In
my station the KAT500
Scope traces for a typical KAT500 serial data interface can be found here -
https://www.dropbox.com/scl/fi/ypk0ks16rl03d55ugm4t9/KAT500-signal-levels.pdf?rlkey=7iahis4xp0jnua3c8s577cxjq=0
I can also confirm that KAT500 works just fine when interfaced with a genuine
MAX 3232 RS-232 line driver.
"Indeed, it is NOT true that the KAT500 uses TTL signal levels for the serial
port. "
Ah, but I said "Isn't it true that the KAT500 USB cable uses RS-232 protocol
but TTL signal levels? " Perhaps I should have been more specific. My
recollection is that the USB/Serial cable transmits a TTL
"Yes. At the point for the extension, the signals are RS-232, not USB. You
should be able to use a much longer cable if need-be."
Isn't it true that the KAT500 USB cable uses RS-232 protocol but TTL signal
levels? TTL may not be as tolerant of length extension as true RS-232.
Certainly no
"I should be able to fix the problem with better decoupling and/or choking of
the breakout box connections."
Problem fixed by adding a 0.01 disc ceramic caps on each of the 4 RCA keyline
jacks on the breakout box. I should have included them when I built it.
Interesting problem though and all
I followed up on the RFI theory and quickly found a solution to the problem.
My TS-590S has a homebrew breakout box on the REMOTE connector. This breakout
box provides key line level shift and key line interrupt for my SteppIR. The
TS-590S ALC control line is on this cable but is not
I found that the power for onset of oscillation is strongly dependent on
frequency:
7.01 C0,L0, SIDE T - max no osc 108 W
7.02 C0, L710, SIDE T - max no osc 118 W
7.03 C0, L710, SIDE T - max no osc 129 W
7.10 C0, L710, SIDE T - max no osc 222 W
7.20 C47, L820, SIDE T - max no osc unknown
"Perhaps check and see if the drive from the TS-590s is varying, or if the gain
of the KPA500 is changing. What does the output meter on the 590 say when this
happens?"
TS-590S power meter does not change nor does TS-590S indicated SWR. However, I
did find that TS-590S ALC reading is cycling.
Thanks to those that replied with suggestions.
This morning I ran some additional testing. I found I could induce the
oscillation at 70 W KPA500 output power. With KPA500 switched to STBY I could
run 100 W from my TS-590S with no anomalies. The only change in the antenna
system
I have a new power oscillation problem that is manifest only on 40 m when using
an attic dipole. Basic station configuration is Kenwood TS-590S, KAT500,
KPA500. As drive power is slowly increased and output power rises above about
100 W the power output falls to zero then slowly rises again.
KAT500 Key In and Key Out RCA jacks are linked by a relay contact but connect
to nothing else. It doesn't make any difference which is In and which is Out,
but I agree the documentation should be consistent.
Andy, k3wyc
__
Elecraft
"Based on the release notes, I think this means that the Yaesu FTDX3000 (and
others) can operate in enhanced mode, like the Kenwood, with both frequency
and band data. Is that correct? If so, what kind of cabling is needed for the
Yaesu for enhanced mode? Can enhanced mode function if
Now available for download. Includes bug fixes for tune hangup and Kenwood
memory channel frequency.
https://elecraft.com/pages/kat500-fully-automatic-tuner-firmware-and-utility
73,
Andy, k3wyc
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That was a head spinning discussion! No Elecraft transceiver here but I've
been working single RX Split with a TS-590S for as long as I have owned it.
For the TS-590 the key to working split pileups is the TF-SET key which swaps
TX and RX VFO as long as it is held. Sounds like Elecraft does
A new user may sign up for this "list" or "reflector" here -
https://mailman.qth.net/mailman/listinfo/elecraft
This portal does not require a callsign, or even a name, to apply for list
membership. It also, as far as I can see, does not specify any rules, or link
to any rules, for
SteppIR will accept up to 200 W without damage and opening the amplifier key
line is the standard way protect SteppIR antennas.
It has been asserted that "NO key line interrupter is needed". However,
Elecraft recognizes that they may be such a need and sells an adapter to
disable keying by
"In the KAT500 manual, page 5, Figure 1 Cabling Diagram, is the better and
safer way to configure the system. NO key line interrupter is needed.
How does an Elecraft station that controls KPA500 and KAT500 using AUX cables
inhibit keying when a SteppIR antenna is moving the tapes? This
"So now I open again for other suggested headsets in the $100 range. The CM500
was a gaming headset so that could be a source. This is going to be a gift for
a friend who badly needs something.
Any more ideas?"
I had been using my Yamaha HP-1 headphones on my Kenwood TS-590. I decided
they
"I just ordered the KPA500/KAT500 combo and W2 watt meter for my K3S. Should I
use the key line interrupt connected to the W2 watt meter or should I connect
the key line interrupt to the KAT500? Do I even need to use key line interrupt
with the K line set up?"
Why would it hurt to have
A beta tester reported that his KAT500 did not track memory channels on his
Kenwood TS-890S. It tracked VFO tuned frequencies correctly.
I confirmed that this regression was introduced in KAT500 firmware alpha 2.10.
Alpha 2.09 correctly tracks Kenwood TS-590 simplex memory channels.
This
"Yeah, I flashed to 2.13 from 1.75 this weekend, and at first things seemed to
be OK, but last night when running the 80M SSB net, I kept having the tuning
change unexpectedly and my KPA500 kept faulting out. "
Hard to make any useful comment without knowing a lot more about your
Elecraft has released updated KAT500 utility, updated serial command reference,
and a beta release of new firmware.
Anyone who was bothered by good tuning solutions being pushed off the stack
should be very interested in the new AB command.
"The problem I am having is: with radio on 17 M, when I run a “tune” sequence,
the KAT does not switch to Ant 3, in fact it will not let me manually switch to
ant 3. I occasionally have the same issue with the tuner not switching on other
bands, to the selected antenna as set up in the utility.
I now have data for nine KPA500 with serial numbers ranging from 11x to 478x
(exact serial number intentionally obscured). Thanks to everyone who
contributed.
The data show no significant increase in gain from the earliest to the latest
serial numbers. However, the data do seem to suggest
"I'd like to share the referenced image but that doesn't seem to be possible
here."
Dropbox link -
https://www.dropbox.com/s/vb18znyn9j0ilmh/6%20m%20doppler%20-2%20snip.PNG?dl=0
Andy, k3wyc
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"If my calculations are correct an aircraft would have to be moving at 700 kts
to give a Doppler shift of 60 Hz. Metro area airports are usual in Class B
airspace with a speed limit of 250 kts. Maximum speed on the BRUSR ONE is 250
kts reducing to 210 kts as they pass my house. At 250 kts
"Doppler caused "spreading" is readily identified ... the spreading is
generally in one direction (because airport "patterns" run in one direction)
and often manifests as a second signal offset by 60-80 Hz (which can be
independently decoded). IMD is generally in both directions and can not be
"Clean FT8 spectra is badly needed, especially in metro areas at 10 meters and
above, where many poor quality FT8 signals abound and wipe out many of the
weaker stations that other stations are trying to receive. Yes, there are
suggestions that folks in the same area all transmit at the same
Thanks to all those who have submitted test data. I shall need more to have
any hope of seeing a correlation so please keep it coming.
Requested data:
Serial number; frequency; drive power; output power (target 500 W); PA voltage
(front panel HV); PA current (front panel CUR); power
"It will remain as clean as the audio, up to the point the ALC begins to kick
in; then it goes bad like any other radio. That’s the fault of ALC, not the
radio."
What goes bad? Nothing goes bad for a Kenwood TS-590S when drive level moves
into the ALC closed loop control range. Remember
I have been told that the gain of the KPA500 has increased over the years it
has been produced. "Early" KPA500 are reported to need 35-39 W to produce 500
W out. "Later" KPA500 are reported to need only 20-25 W for full output. The
difference in gain has been attributed to difference in the
"but I guarantee that it can be easily done with a TS-590S as well. You just
didn't do it right."
Ok, please tell me how to do that. Specific settings please from a test that
you actually ran with a TS-590S.
My tests had all audio drive sliders to max and ALC meter hard on the stop.
Clean
Just a few comments on dirty signals and the rigs that can, if badly adjusted,
produce them.
I've been using a Kenwood TS-590S for about 10 years. I was asked to give a
couple of digital modes presentations to the local club . I was seeing so many
foul JT65, and now FT8 signals, that I
Since you use DXLab I'd suggest checking Commander's "User-defined Controls"
configuration. Is there a slider for Mic gain? If so, is it configured to
"Initialize radio"?
In Commander click "Help" then select "sliders" for more info.
Andy, k3wyc
"The issue: The fan comes on in a very short time - less than 20 seconds - and
the temp display runs up to 50+ degrees. If I start calling CQ or get into a
QSO, it doesn’t take long for the temp to show over 60 degrees and the fan is
running at max."
Max fan speed of a KPA500 is setting 6.
"The specific problem I have is that, for 6 meters, I want to use ANT 2 but the
KAT500 is not letting me change from ANT 3. And while I am not using ANT 1,
I’m not able to configure a band/antenna combination such that I can only
switch between ANT 2 and ANT 3. "
I works correctly for me
It doesn't matter how many "sound cards" are in the system. What does matter
is that the one assigned to digital modes is not also assigned as the system
"default" device. It is easy to get this wrong even when two or more "sound
cards" are available.
I think you guys may be assuming
CAT allows true rig split or "fake it" modes of WSJT-X. In either case the
modulation frequency is limited to the range 1,500 to 2,000 Hz and any audio
harmonics fall outside the TX passband of most transceivers. CAT and the
WSJT-X split modes do not prevent generation of audio harmonics but
Well that's an interesting failure report. I don't see any obvious single
factor except for overheating of the entire PA module.
Was the fan functioning normally, air vents clear, and external airflow
unobstructed?
"Capton tape on the "S" bracket is interesting. Did they mean "Kapton tape on
"It can't be solved. The SSB and/or Data at that AF MARS frequency is just
slightly below the band pass filter change over to the 5.3 bandpass filter
on the KPA500. That means that when you are on SSB, part of your rf envelope
crosses over to the 5.3 band filter which causes the amp to switch to
"And what I am finding is that the tuner switch can only identify the two and
not the third one.
Any recommendations on where I should begin to sort this out?"
ANT availability for selection can be configured by band. Connect the KT500
utility and use it to set your antenna configuration
"My KPA500 is showing 57-58 VDC at 450-500 watts out, and 71-72 VDC on rx."
That's a much smaller spread than I see with my KPA500. Are you powering from
240 VAC or 120 VAC? Running on nominal 120 VAC I have my RX PA volts currently
reading 81.8 and it still sometimes sags just below 60 V on
"The Adobe Reader “Find” box doesn’t recognize all caps. "
Yes it does but you have to specify whether the search text is case sensitive
or not. Click the "gear" icon. Better yet, used the advanced search function.
Andy, k3wyc
__
Is the KPA500 being keyed on 6 m? (Does the asterisk appear in the KPA500
display?)
Some rigs, such as the Kenwood TS-590, require the keying output to be
specified separately for 6 m than for the HF bands.
Andy, k3wyc
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Was the issue resolved? Any update on the state of the investigation and
whether a firmware defect was confirmed?
Thanks and 73,
Andy, k3wyc
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"Also, which should be obvious, the KAT500 is trained on each band and acts
appropriately with V1.75. Why it doesn't with V2.05 is currently a mystery. "
No, it was not obvious to me that you had trained all of each band. I had the
impression that you had trained only the FT8 frequencies in
"The question is why does V2.05 appear to ignore what should be memorized
tuning solutions?"
V2.05 does not ignore memorized solutions.
I wonder if V2.05 is selecting an adjacent "bin" that you had not tuned and
memorized with V1.75. There was a change in bin boundary frequencies in V2.05.
"The latest revision of the schematic for the KPA500 TR Switch shows a Zener
diode at the gate of Q4 in place of R3, the 100K resistor previously."
What is the latest revision? I have Rev D which is later than any I have found
on-line but it shows R3 not a Zener.
Andy, k3wyc
"(hope yours is cheaper than mine.replaced finals..$733 including shipping
back to me!)"
How did you manage to blow the finals? Are the internal protections of the
KPA1500 inadequate in some way?
It took quite a bit of testing for me to find out why my KPA500 being shut down
when it was
"k3wyc said:
> ... The spotted frequency should be the suppressed carrier frequency ...
I don't think so. Most modern CW rigs that I am aware of, including the K3,
display the actual transmitted frequency on the dial, not the SSB
suppressed carrier frequency."
I agree. Kenwood TS-590 also
"If the spotter was using a rig without an adjustable sidetone, wouldn't the
frequency they spot be dependent upon the tone they prefer to hear?"
The spotted frequency should be the suppressed carrier frequency which is
independent of the choice of tone frequency. Remember there are very few
"He tells me that a failed R16 on the power supply board should have no effect
on the 60V supply, ."
No, of course it won't. It will only prevent 270 V being produced if 60 V is
present. The amplifier is heavy and will be expensive to ship. Why not
diagnose the problem and just fix
I doubt you will see anything useful if you open the rig. Multi contact jacks
are usually closed assemblies not like the open contact types we used years ago.
There have been discussions of broken plug tips in Kenwood and Elecraft group.
There seem to be two solutions. Either change the
"If you check the schematics, the 270V is made/comes from the power
supply...BUT the 60V enable relay (feeds the voltage divider and read on the
front panel) is on the PA board... "
May I suggest that you look at KPA Power Supply Schematic sheet 1 of 2 and
locate relay K1 (60 V Enable) which
"I think it may actually be the other way around... The 60V relay does not
close if 270V is missing?"
Assume 60 V Enable relay K1 is not closed. How would 270 V be produced? The
secondary winding of T1 is open circuit.
Andy, k3wyc
HV and 270V are separate power supply rails but, if my read of the schematic is
correct, 270 V depends on 60 V being present. 60 V requires the interlock
switch to be closed.
Diagnosing this may require having the top off and the interlock defeated.
Everyone should evaluate their own
Don't need to have ferrite in the antenna system to see this sort of SWR
"runaway". I have the same problem with my home brew small transmitting loop
if I run over 100 W.
Spent some time trying to figure out what was heating and causing the loop's
resonant frequency to shift. My preliminary
Building the kit is not difficult is you have basic mechanical skills. There
are LOTS of screws. I suggest laying out the parts and making a full inventory
before starting.
Elecraft has used various torroidal main transformers. The one that came with
my kit had almost zero clearance. I used
"I though Elecraft wanted HV to be kept at or above 60 to avoid unacceptable
IMD. No sure where I found that but don't think I imagined it. "
The problem with making measurements is that one may not like the results.
It's a nice warm afternoon here in Glendale AZ and I expect every air
"Seems a little low, but it's happy."
I though Elecraft wanted HV to be kept at or above 60 to avoid unacceptable
IMD. No sure where I found that but don't think I imagined it. Anyone have a
reference?
Andy, k3wyc
__
Elecraft
"I don't remember the AC, can check it later, but think its 231-232."
Your use of nominal 240 would explain why your HV sag is a lot less than mine.
I have always run my KPA500 on 120.
Maybe someone who uses nominal 240 would provide their typical loaded and
unloaded HV values.
Andy, k3wyc
"My kpa500 has the taps set to provide 71-72 VDC no load and drops to 60 at 500
watts."
Do you know how your house line input voltage varies? Mine can be as high as
122 and as low as 118 and the local transformer is less than 50 ft from my
house.
I see unloaded KPA500 voltage over 80 with
"I cannot find that "something.""
That something is likely Microsoft Windows. I declined Win 10 and never
regretted that decision. It seems Win 11 is even worse than Win 10.
My station computer in Win 8.1 64 bit. It never changes COM port assignments.
I have other XP Sp3 computers that
"These is nothing unique about the Elecraft serial cable except possibly the
radio side connector. Basically it's a USB to RS232 Ground/transmit/Receive
cable."
I think you may find that some Elecraft serial cables use TTL levels and are
not RS-232 compliant. Doesn't matter if used for
"The result is that it's very difficult to cause overdrive and splatter with a
K4, even if you try to do it intentionally."
Same is true for the much older Kenwood TS-590S. I have tried several times to
produce dirty signals to illustrate digital modes presentations. I have never
been able
"Still, that frenzied fun-house of robotic birdcalls did serve as a convenient
marker for the end of each CW segment."
Which bands have a CW segment? Did I miss a band plan change?
Andy, k3wyc
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I have operated WSJT-X modes for many years HF-6 meters. I'm in a very large
metro area with lots of active FT-8 users. I have learned that stations with
perfect signals on the HF bands can show all sort of artifacts on 6 meters.
For many of these stations it is not because the signals are
"You should be running fans full-speed under those conditions if you want it to
live long! "
Please share any data you have that supports any claim than running continuous
full fan on any Elecraft amplifier has any advantage over letting the firmware
control the fans based on PA temperature.
"I seem to remember there was a change for those wire links but don't have the
details here."
This discussion suggests there were two board configurations - one with both
links on the same side of the board and the other with one link on each side.
It's not clear when the change was made or
What mode is the KAT500 in when you power up and see the wrong antenna selected?
What firmware version is loaded in your KAT500?
There was a firmware defect that could cause the wrong antenna to be selected
in BYP mode but it is fixed in the current firmware.
I seem to remember there was a
"Anybody out there super-well versed in the behavior of the half-wave dipole?"
There are only two possible answers:
Yes
No
I speculate that, given the expertise of this group, "Yes" is the right answer.
However, I have no clue how the answer to your question will be useful to you.
I suppose
One thing that you may not understand is that MAN with BYP active is the same
electrically as BYP mode).
I use all 3 ANT ports of my KAT500 and never used any KAT mode except MAN. Some
of my antennas work fine in MAN/Byp and others require some help with L and/or
C. All antenna switching is
"Is there data showing more dissipated heat with lower output in solid state
amplifiers? "
I have test data for my KPA500 and it's very obvious that this amplifier has
higher PA heat dissipation at half power than at full power. Not just less
efficient as a percentage of power output but the
Sorry - too early in the morning - "KPA500" not "KPA 500".
Andy, k3wyc
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This
"Now, my question for everyone reading - when is it that you feel the need to
set the fan speed above 0?"
I coded my station controller to provide an option to start KPA 500 fan at
start of TX and have it run for a fixed time after TX stops. My test data
showed no significant advantage in
"Just gave it a try. No joy, same result - lowered rx signal strength on the
IC-705. Jack indicated that the K3 sets the Vcc rail to zero volts on power
off, and that is causing the amp to go into Operate mode. "
Maybe I lost the plot but wasn't the problem that the KPA500 was being keyed,
"Pulling the audio cable when I want to use the IC-705 with the amp isn’t
practical due to the location of the radio."
The high density 15 pin connectors used on the Aux cable is readily available
and inexpensive. Why not make an adapter that allows the PTT line (pin 10) to
be switched
"The reason I don’t suspect the PIN diodes is that the KPA works properly with
the K3. "
Sorry, I missed that part.
73,
Andy, k3wyc
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"p.s. do you have any idea what Jack was talking about when he said "switch the
RADIO setting of the KPA from K3 to something else, either Serial or Analog”??"
KPA500 menu / Radio / (Serial/Analog/BCD/K3).
Andy, k3wyc
__
Elecraft
"What are the uses for the TCXO option in a K3? Why would I want one?"
TCXO means "Temperature Compensated Crystal Oscillator". You need one if the
frequency drift caused by rig temperature change causes a problem at the
frequencies, and with the modes, you operate. Leave the rig powered all
"However, what I’m seeing is that when the amp is in OPER mode, my receive
signal strength drops way, way off to the point I have to go full AF volume to
hear signals. If I put the amp in STBY, signal levels go back to normal."
These exact symptoms have been associated in past reports with a
"It’s also worth mentioning that if the radio and the amp are hard wired
together, changing the band using the buttons on the front of the amp
automatically changes the band on the radio."
It should be possible to disable the KPA 500 band buttons but it isn't. They
are a "bandaid" for the
My test data show that, of all the bands my KPA500 will work on, 20 m has the
lowest PA efficiency. My test data also show that the KPA500 efficiency, and
therefore PA dissipation, is very sensitive to load matching.
So, if you are on 20 m and with a poor match, your 60 V PSU will have a high
"Yep. I think it’s the connections. The resistor network seems to be fine
and the right values."
Then I'd be looking at U18 and U14B.
Following signals through KPA500 schematics would be a lot easier if they
didn't change the signal names multiple times.
Andy, k3wyc
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