Re: [Elecraft] KPA500 Issue

[David Woolley]

Key clicks don't require non-linearity.  They are the result of 
modulating with a signal that has an infinite bandwidth, because of the 
sharp transitions at leading and trailing edges.  That results in 
infinite side bands.  (Actually any signal that communicates information 
in finite time will have infinite side bands, but by correct shaping you 
can make them very small.)


--
David Woolley
Owner K2 06123.


On 01/04/2022 23:06, Jim Brown wrote:

On 4/1/2022 2:35 PM, kevin wrote:

It is more accurately referenced as Discontinuous Wave.


Actually, it is 100% amplitude modulation of a carrier by a rectangular 
wave train. That modulation excites non-linearity in the transmitter 
signal chain and produce intermodulation distortion that is heard as 
clicks.



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Re: [Elecraft] KPA500 Issue

[James Bennett via Elecraft]

No - it does not spontaneously go into transmit more. The problem is that on 
the non-Elecraft radio, placing the KPA into transmit mode (with a button push 
on the KPA) drops the non-Elecraft radio’s receive signal tremendously. See 
Jack’s explanation in an earlier post on what the K3 is doing to the “system” 
when it is powered off.

Jim / K7TXA

> On Apr 1, 2022, at 6:44 PM, Andy Durbin  wrote:
> 
> "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, 
> not that it spontaneously went to operate mode.  KPA500 won't be keyed unless 
> one of the two keying inputs is pulled low.
> 
> Take control of KPA keying source and doesn't the problem go away?
> 
> Andy, k3wyc
> 
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Re: [Elecraft] KPA500 Issue

[Jack Brindle via Elecraft]

I don’t think your point #1 is valid. The K3 will cause the KPA to change bands 
when it does a band change and sends out changed bits on the BAND signals. If 
you don’t change bands on the K3, then the KPA won’t have a reason to change. 
The problem with this, when RADIO = K3, is that tapping a band button on the 
KPA _will_ send an Auxbus command to the K3 indicating that a band button has 
been pressed. The key here is then to set the RADIO setting to something else. 
If you do not use the KPA to select a band on the K3, then try setting RADIO to 
BCD. Then, when the K3 changes bands, it will tell the KPA about the new band 
by changing the BAND signals, but the KPA will not send anything on the AUXBUS 
that causes the K3 to perform a band change.

The KPA500 is very versatile. If you make the right selection of its settings, 
it will do what you want. But it cannot overcome that PTT signal being held low 
by the K3. Use the KPA manual as a guide to tell you what you need to set and 
try it. And, for more information on this specific subject, get Fred Cady’s 
book on the KPA500. It has a lot of good info.

I still think that the use of the key block adapter along with a switch to 
select which PTT signal goes to the KPA500 & KAT500 would be your best bet. 
Also, buying a house without those restrictions… ;-)

For the those lurking, Jim and I have been friends for a long time, both 
members of the Northern California Contest Club. We escaped CA about the same 
time, commiserating on how expensive it was to move. At least I don’t have any 
restrictions now. It helps to be married to a ham who understands these things… 
;-)

Keep at it, Jim. I am sure we can devise a good solution for using both rigs.

73,
Jack, W6FB
PS. Watch for us in the La QSO Party on Saturday. It should be fun!


> On Apr 1, 2022, at 6:47 PM, James Bennett via Elecraft 
>  wrote:
> 
> Chuck,
> 
> 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. 
> 
> I see the following options -
> 
> 1. Always put the K3 on the same band as the IC-705 if I want to run QRO with 
> the 705.
> 
> 2. Never use the 705 in QRO mode.
> 
> 3. Disconnect the K3 from the system, sell it, wait for the K4D to be 
> delivered, and use the 705 all by itself with the amp and tuner in the mean 
> time. 
> 
> Option #1 works but is a minor PITA. Option #2 - maybe. Option #3 - probably 
> the choice to make, as the K3/P3 was going to be sold anyway, in anticipation 
> of the K4D arrival. Just hoping I’ll live long enough to see the new radio 
> delivered.
> 
> Oh well, nothing in life is simple. At least I’ve got options and am able to 
> get on the air. :-)
> 
> 
> 
> 
>> On Apr 1, 2022, at 3:51 PM, Chuck Chandler  wrote:
>> 
>> Hhhmmm... I'm coming late to this thread, as I wasn't paying attention
>> before.
>> 
>> Please forgive me if I have missed something but -
>> 
>> I have, in the past, used both a K3S AND an old Yaesu FT-101ZD with my
>> KPA/KAT 500 power combo.  I *THINK* that is similar to what Jim is trying
>> to do.
>> 
>> Here is what I found, if it helps.
>> 
>> When the K3S is on, it communicates with the KAT/KPA.  However, when it is
>> turned off, it leaves the KPA/KAT in a state where they are not prepared to
>> accept input.  I forget the specifics, because I have since provided the
>> 101ZD with it's own amp.
>> 
>> Try this - Turn off the K3S.  Turn off the KPA.
>> 
>> Turn the KPA back on, with the other radio connected to the RF input and at
>> least an RCA keyline connected for the PTT.  See if it works.
>> 
>> IIRC, this was what I had to do.
>> 
>> If anyone needs the specifics as to WHY it works that way, I can try to dig
>> out the old emails with Elecraft.  And, it's been a while so I may be
>> mis-remembering the details.  But, I know it worked.
>> 
>> I hope this helps...
>> 
>> 73 de Chuck, WS1L
>> 
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Re: [Elecraft] KPA500 Issue

[Andy Durbin]

"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, 
not that it spontaneously went to operate mode.  KPA500 won't be keyed unless 
one of the two keying inputs is pulled low.

Take control of KPA keying source and doesn't the problem go away?

Andy, k3wyc

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Re: [Elecraft] KPA500 Issue

[James Bennett via Elecraft]

Chuck,

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. 

I see the following options -

1. Always put the K3 on the same band as the IC-705 if I want to run QRO with 
the 705.

2. Never use the 705 in QRO mode.

3. Disconnect the K3 from the system, sell it, wait for the K4D to be 
delivered, and use the 705 all by itself with the amp and tuner in the mean 
time. 

Option #1 works but is a minor PITA. Option #2 - maybe. Option #3 - probably 
the choice to make, as the K3/P3 was going to be sold anyway, in anticipation 
of the K4D arrival. Just hoping I’ll live long enough to see the new radio 
delivered.

Oh well, nothing in life is simple. At least I’ve got options and am able to 
get on the air. :-)




> On Apr 1, 2022, at 3:51 PM, Chuck Chandler  wrote:
> 
> Hhhmmm... I'm coming late to this thread, as I wasn't paying attention
> before.
> 
> Please forgive me if I have missed something but -
> 
> I have, in the past, used both a K3S AND an old Yaesu FT-101ZD with my
> KPA/KAT 500 power combo.  I *THINK* that is similar to what Jim is trying
> to do.
> 
> Here is what I found, if it helps.
> 
> When the K3S is on, it communicates with the KAT/KPA.  However, when it is
> turned off, it leaves the KPA/KAT in a state where they are not prepared to
> accept input.  I forget the specifics, because I have since provided the
> 101ZD with it's own amp.
> 
> Try this - Turn off the K3S.  Turn off the KPA.
> 
> Turn the KPA back on, with the other radio connected to the RF input and at
> least an RCA keyline connected for the PTT.  See if it works.
> 
> IIRC, this was what I had to do.
> 
> If anyone needs the specifics as to WHY it works that way, I can try to dig
> out the old emails with Elecraft.  And, it's been a while so I may be
> mis-remembering the details.  But, I know it worked.
> 
> I hope this helps...
> 
> 73 de Chuck, WS1L
> 
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Re: [Elecraft] KPA500 Issue

[Fred Jensen]

Or perhaps OOKPWM?  That was the only available modulating technique for 
spark transmitters.  For all it's apparent simplicity, it is still 
possible to create a rotten signal, and it is notoriously difficult to 
decode ... unless you're a human being.


My modest home station is comprised of only a K3, P3, RemoteRig 
RRC-1258, Winkey, 3 paddles, and one hand key, and the "behind the desk" 
part certainly does not look like "wireless." 


73,

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

Jim Brown wrote on 4/1/2022 3:06 PM:

On 4/1/2022 2:35 PM, kevin wrote:

It is more accurately referenced as Discontinuous Wave.


Actually, it is 100% amplitude modulation of a carrier by a 
rectangular wave train. That modulation excites non-linearity in the 
transmitter signal chain and produce intermodulation distortion that 
is heard as clicks.


73, Jim K9YC




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Re: [Elecraft] KPA500 Issue

[Jim Brown]

On 4/1/2022 2:35 PM, kevin wrote:

It is more accurately referenced as Discontinuous Wave.


Actually, it is 100% amplitude modulation of a carrier by a rectangular 
wave train. That modulation excites non-linearity in the transmitter 
signal chain and produce intermodulation distortion that is heard as clicks.


73, Jim K9YC
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Re: [Elecraft] KPA500 Issue

[Chuck Chandler]

Hhhmmm... I'm coming late to this thread, as I wasn't paying attention
before.

Please forgive me if I have missed something but -

I have, in the past, used both a K3S AND an old Yaesu FT-101ZD with my
KPA/KAT 500 power combo.  I *THINK* that is similar to what Jim is trying
to do.

Here is what I found, if it helps.

When the K3S is on, it communicates with the KAT/KPA.  However, when it is
turned off, it leaves the KPA/KAT in a state where they are not prepared to
accept input.  I forget the specifics, because I have since provided the
101ZD with it's own amp.

Try this - Turn off the K3S.  Turn off the KPA.

Turn the KPA back on, with the other radio connected to the RF input and at
least an RCA keyline connected for the PTT.  See if it works.

IIRC, this was what I had to do.

If anyone needs the specifics as to WHY it works that way, I can try to dig
out the old emails with Elecraft.  And, it's been a while so I may be
mis-remembering the details.  But, I know it worked.

I hope this helps...

73 de Chuck, WS1L

chandler...@gmail.com


On Fri, Apr 1, 2022 at 11:01 AM James Bennett via Elecraft <
elecraft@mailman.qth.net> wrote:

> Well, it looks like there is no simple solution to this dilemma. I was
> hoping to (easily) be able to use the amp with either rig while both were
> here in the shack. 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. I changed
> the “Radio” setting from K3 to Analog and Serial, but with the cables
> attached, the result is the same - as soon as the amp is put in OPER mode
> it goes into transmit state (* showing on the LCD).
>
> So, the only option for the time being is to always have the K3 powered up
> and on the band that I want to operate the IC-705 on. Just need to keep
> their frequencies separated as much as I can. Unless Jack comes up with an
> alternate…! :-) :-)
>
> Jim / K7TXA
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Re: [Elecraft] KPA500 Issue

[kevin]

For the same reason we call using Morse Code CW.

It is more accurately referenced as Discontinuous Wave.

   73,  Kevin.  KD5ONS


On 4/1/22 13:23, Fred Jensen wrote:

Why do we call this "wireless?"

73,

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

Jack Brindle via Elecraft wrote on 3/31/2022 9:47 PM:
OK, now this is starting to make sense. Jim’s K3 has a KIO3, not the 
newer KIO3B. On the older board, the BAND and PTT lines have pullup 
resistors to the Vcc rail.
When the K3 is powered off, that Vcc rail is at 0 volts, which means 
the pull-ups are now pulldowns. Thus the K3 is inadvertently keying 
the KPA500. If the KPA
detects that the KEY input is low when the user tries to put it into 
OPER mode, the amplifier will reject the request and stay in STBY. 
Thus the condition that

Jim is seeing.

Try disconnecting the AUXIO cable from the KPA500 and see if it now 
operates properly. You may actually need to connect the KAT500 to the 
KPA using both the AuxIO

and phono cables (for PTT) depending on which radio is in use.

The main issue is how to disconnect the PTT signal from the K3 to the 
KPA when using the Icom. Otherwise you may be able to leave the AuxIO 
cable connected.
I know that Fred Cady discussed sharing a KPA between two radios in 
his book, but has anyone solved this situation - one radio is a K3, 
the other something else?


73,
Jack, W6FB






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Re: [Elecraft] KPA500 Issue

[Fred Jensen]

Why do we call this "wireless?"

73,

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

Jack Brindle via Elecraft wrote on 3/31/2022 9:47 PM:

OK, now this is starting to make sense. Jim’s K3 has a KIO3, not the newer 
KIO3B. On the older board, the BAND and PTT lines have pullup resistors to the 
Vcc rail.
When the K3 is powered off, that Vcc rail is at 0 volts, which means the 
pull-ups are now pulldowns. Thus the K3 is inadvertently keying the KPA500. If 
the KPA
detects that the KEY input is low when the user tries to put it into OPER mode, 
the amplifier will reject the request and stay in STBY. Thus the condition that
Jim is seeing.

Try disconnecting the AUXIO cable from the KPA500 and see if it now operates 
properly. You may actually need to connect the KAT500 to the KPA using both the 
AuxIO
and phono cables (for PTT) depending on which radio is in use.

The main issue is how to disconnect the PTT signal from the K3 to the KPA when 
using the Icom. Otherwise you may be able to leave the AuxIO cable connected.
I know that Fred Cady discussed sharing a KPA between two radios in his book, 
but has anyone solved this situation - one radio is a K3, the other something 
else?

73,
Jack, W6FB





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Re: [Elecraft] KPA500 Issue

[ws6x.ars]

Jim,
You are correct! It is clearly not the same problem. I was trying to correct my 
"bad memory" offering from last evening.
Thanks, Jim - WS6X 

-Original Message-
From: elecraft-boun...@mailman.qth.net On Behalf Of James Bennett via Elecraft
Sent: Friday, April 01, 2022 3:36 PM
To: Elecraft Reflector Reflector 
Subject: Re: [Elecraft] KPA500 Issue

Jim,

I don’t think this is the same problem as you had. The receive signal on my K3 
does NOT drop off when placing the amp in OPER. With my antenna switched over 
to the IC-705 (not the K3), the received signal does drop off when the amp is 
placed into OPER mode. Thus, I’m pretty certain that R7 and the PIN diodes are 
OK - the K3 is not affected. 

Jim / K7TXA 

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Re: [Elecraft] KPA500 Issue

[James Bennett via Elecraft]

Jim,

I don’t think this is the same problem as you had. The receive signal on my K3 
does NOT drop off when placing the amp in OPER. With my antenna switched over 
to the IC-705 (not the K3), the received signal does drop off when the amp is 
placed into OPER mode. Thus, I’m pretty certain that R7 and the PIN diodes are 
OK - the K3 is not affected. 

Jim / K7TXA
> 
> Jim, Andy et al,
> 
> I weighed in on this thread last evening from memory in response to Andy's
> comment, above. By age 77, I should have learned not to rely on memory. As
> it turns out, my memory was faulty.
> 
> So, even though it appears many have pointed Jim to a useful, unrelated
> solution, I will now provide the correct information about the issue and fix
> with my KPA500 almost one year ago.
> 
> At first glance, my symptoms were nearly identical to what Jim is reporting:
> With ALL control cables between the K3s and the KPA500 completely
> disconnected (only the input and output coax cables connected to the amp),
> every time the amp is manually switched from "STBY" to "OPER" the receive
> signal on the K3s dropped about 20 dB.
> 
> As many suggested, the problem was in the T/R circuit. In my case the
> culprit was R7. This 51 Ohm resistor was toast -- completely open. My fix
> was to parallel a pair of 1/4 Watt, 100 Ohm resistors across the R7 pads.
> Problem solved. The KPA500 has been on good behavior since.
> 
> Hopefully, this information might be useful to someone in the future.
> 
> Jim - WS6X 
> 
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Re: [Elecraft] KPA500 Issue

[ws6x.ars]

"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 failure of
the TR switch PIN diodes.  Jack's idea of incorrect band can be easily
confirmed, or eliminated, by looking at the KPA500 band display.

Andy, k3wyc



Jim, Andy et al,

I weighed in on this thread last evening from memory in response to Andy's
comment, above. By age 77, I should have learned not to rely on memory. As
it turns out, my memory was faulty.

So, even though it appears many have pointed Jim to a useful, unrelated
solution, I will now provide the correct information about the issue and fix
with my KPA500 almost one year ago.

At first glance, my symptoms were nearly identical to what Jim is reporting:
With ALL control cables between the K3s and the KPA500 completely
disconnected (only the input and output coax cables connected to the amp),
every time the amp is manually switched from "STBY" to "OPER" the receive
signal on the K3s dropped about 20 dB.

As many suggested, the problem was in the T/R circuit. In my case the
culprit was R7. This 51 Ohm resistor was toast -- completely open. My fix
was to parallel a pair of 1/4 Watt, 100 Ohm resistors across the R7 pads.
Problem solved. The KPA500 has been on good behavior since.

Hopefully, this information might be useful to someone in the future.

Jim - WS6X 

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Re: [Elecraft] KPA500 Issue

[Ken K6MR]

"However, if the rigs are on different bands, you do need to rely on frequency 
sensing by the amp."

You don't have to do this, but it does take a bit of extra hardware/software to 
interface two K3s to a KPA1500.  In addition to the necessary relays to switch 
the RF path you can use an Arduino to manage the band data as well as the Aux 
Bus messages.  I also use a MicroHam MK2R+ to point the amp at the correct 
radio.  It is seamless.  I have the amp in a closet and never touch it, 
monitored only by the remote software.  I can switch instantly between radios 
in a SO2R setup and interleave QSOs.

Ken K6MR



From: elecraft-boun...@mailman.qth.net  on 
behalf of Frank Scolaro 
Sent: Friday, April 1, 2022 8:46 AM
To: James Bennett ; Elecraft Reflector Reflector 

Subject: Re: [Elecraft] KPA500 Issue

Jim,.

I use the "1A2R" (one amp tw0 radios) from 4O4A.  I have two rigs share my 
KPA1500.  However, if the rigs are on different bands, you do need to rely on 
frequency sensing by the amp.  Not sure if the KPA500 does that.

GL
Frank, W2YK

-Original Message-
From: James Bennett
Sent: Apr 1, 2022 11:02 AM
To: Elecraft Reflector Reflector
Subject: Re: [Elecraft] KPA500 Issue

Well, it looks like there is no simple solution to this dilemma. I was hoping 
to (easily) be able to use the amp with either rig while both were here in the 
shack. 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. I changed the “Radio” setting from 
K3 to Analog and Serial, but with the cables attached, the result is the same - 
as soon as the amp is put in OPER mode it goes into transmit state (* showing 
on the LCD).

So, the only option for the time being is to always have the K3 powered up and 
on the band that I want to operate the IC-705 on. Just need to keep their 
frequencies separated as much as I can. Unless Jack comes up with an 
alternate…! :-) :-)

Jim / K7TXA
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Re: [Elecraft] KPA500 Issue

[RALPH TURK]

In the attached email Frank W2yk wrote the 1A2R from 404A.  I only find a 403.
Please advise 
Ralph, w7HSG/AFA9RT
> On 04/01/2022 9:48 AM Rick Bates, NK7I  wrote:
> 
>  
> It does.  But you HAVE to remember to send a dit on each band change so 
> the amp knows where you are.
> 
> 73,
> Rick NK7I
> 
> 
> On 4/1/2022 8:46 AM, Frank Scolaro wrote:
> > Jim,.
> >   
> > I use the "1A2R" (one amp tw0 radios) from 4O4A.  I have two rigs share my 
> > KPA1500.  However, if the rigs are on different bands, you do need to rely 
> > on frequency sensing by the amp.  Not sure if the KPA500 does that.
> >   
> > GL
> > Frank, W2YK
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Re: [Elecraft] KPA500 Issue

[Andy Durbin]

"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 between K3 and Icom?

AUX pin 10 (Ken in) and RCA Key jack are diode OR'd to drive the same KA500 
internal Keying signal.

Andy, k3wyc

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Re: [Elecraft] KPA500 Issue

[Rick Bates, NK7I]

It does.  But you HAVE to remember to send a dit on each band change so 
the amp knows where you are.


73,
Rick NK7I


On 4/1/2022 8:46 AM, Frank Scolaro wrote:

Jim,.
  
I use the "1A2R" (one amp tw0 radios) from 4O4A.  I have two rigs share my KPA1500.  However, if the rigs are on different bands, you do need to rely on frequency sensing by the amp.  Not sure if the KPA500 does that.
  
GL

Frank, W2YK

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Re: [Elecraft] KPA500 Issue

[Frank Scolaro]

Jim,.
 
I use the "1A2R" (one amp tw0 radios) from 4O4A.  I have two rigs share my 
KPA1500.  However, if the rigs are on different bands, you do need to rely on 
frequency sensing by the amp.  Not sure if the KPA500 does that.  
 
GL
Frank, W2YK
 
-Original Message-
From: James Bennett 
Sent: Apr 1, 2022 11:02 AM
To: Elecraft Reflector Reflector 
Subject: Re: [Elecraft] KPA500 Issue
 
Well, it looks like there is no simple solution to this dilemma. I was hoping 
to (easily) be able to use the amp with either rig while both were here in the 
shack. 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. I changed the “Radio” setting from 
K3 to Analog and Serial, but with the cables attached, the result is the same - 
as soon as the amp is put in OPER mode it goes into transmit state (* showing 
on the LCD).
 
So, the only option for the time being is to always have the K3 powered up and 
on the band that I want to operate the IC-705 on. Just need to keep their 
frequencies separated as much as I can. Unless Jack comes up with an 
alternate…! :-) :-)
 
Jim / K7TXA
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Re: [Elecraft] KPA500 Issue

[James Bennett via Elecraft]

Well, it looks like there is no simple solution to this dilemma. I was hoping 
to (easily) be able to use the amp with either rig while both were here in the 
shack. 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. I changed the “Radio” setting from 
K3 to Analog and Serial, but with the cables attached, the result is the same - 
as soon as the amp is put in OPER mode it goes into transmit state (* showing 
on the LCD). 

So, the only option for the time being is to always have the K3 powered up and 
on the band that I want to operate the IC-705 on. Just need to keep their 
frequencies separated as much as I can. Unless Jack comes up with an 
alternate…! :-) :-)

Jim / K7TXA
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Re: [Elecraft] KPA500 Issue

[Andy Durbin]

"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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Re: [Elecraft] KPA500 Issue

[Jack Brindle via Elecraft]

Now let me answer my own question. There is a key-line interrupter adapter that 
I believe comes with the AUXIO cable. This is an HD-15 type adapter that will 
block the PTT signal from the K3 to the AUXIO cable. Use this, then you will 
need to connect the K3 to the KAT500/KPA500 using a phono cable. You will 
probably want to add a switch so that you can select the K3 or Icom radios for 
the PTT line to the KPA/KAT.

Once again, Fred Cady had the answer in his “Elecraft KPA500 Amplifier and 
KAT500 Tuner” guide. I really miss that guy…

73,
Jack W6FB


> On Mar 31, 2022, at 11:47 PM, Jack Brindle via Elecraft 
>  wrote:
> 
> OK, now this is starting to make sense. Jim’s K3 has a KIO3, not the newer 
> KIO3B. On the older board, the BAND and PTT lines have pullup resistors to 
> the Vcc rail.
> When the K3 is powered off, that Vcc rail is at 0 volts, which means the 
> pull-ups are now pulldowns. Thus the K3 is inadvertently keying the KPA500. 
> If the KPA
> detects that the KEY input is low when the user tries to put it into OPER 
> mode, the amplifier will reject the request and stay in STBY. Thus the 
> condition that
> Jim is seeing.
> 
> Try disconnecting the AUXIO cable from the KPA500 and see if it now operates 
> properly. You may actually need to connect the KAT500 to the KPA using both 
> the AuxIO
> and phono cables (for PTT) depending on which radio is in use. 
> 
> The main issue is how to disconnect the PTT signal from the K3 to the KPA 
> when using the Icom. Otherwise you may be able to leave the AuxIO cable 
> connected.
> I know that Fred Cady discussed sharing a KPA between two radios in his book, 
> but has anyone solved this situation - one radio is a K3, the other something 
> else?
> 
> 73,
> Jack, W6FB
> 
>> On Mar 31, 2022, at 9:11 PM, James Bennett via Elecraft 
>>  wrote:
>> 
>> Bob -
>> 
>> The * appears when I key the K3 and the amp is in operate mode. Likewise if 
>> I key the 705 and the amp is in operate mode, with the K3 powered on.
>> 
>> If I power off the K3 and place the amp in operate mode WITHOUT KEYING IT, 
>> the * appears, so you are correct - the amp thinks it is being keyed.
>> 
>> There is a jack on the 705 that allows one to key an external amp. I have 
>> that line running to the amp. Disconnecting it makes no difference the * 
>> appears as soon as I put the amp into operate mode. If I power on the K3, 
>> this does not happen. However, with the K3 powered on and that cable 
>> disconnected, the amp does not key at all, so it is working as expected - 
>> but only with the K3 powered on. Somewhere the K3 is getting its foot in the 
>> door when powered off…
>> 
>> Jim / K7TXA
>> 
>> 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”??
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Re: [Elecraft] KPA500 Issue

[Jack Brindle via Elecraft]

OK, now this is starting to make sense. Jim’s K3 has a KIO3, not the newer 
KIO3B. On the older board, the BAND and PTT lines have pullup resistors to the 
Vcc rail.
When the K3 is powered off, that Vcc rail is at 0 volts, which means the 
pull-ups are now pulldowns. Thus the K3 is inadvertently keying the KPA500. If 
the KPA
detects that the KEY input is low when the user tries to put it into OPER mode, 
the amplifier will reject the request and stay in STBY. Thus the condition that
Jim is seeing.

Try disconnecting the AUXIO cable from the KPA500 and see if it now operates 
properly. You may actually need to connect the KAT500 to the KPA using both the 
AuxIO
and phono cables (for PTT) depending on which radio is in use. 

The main issue is how to disconnect the PTT signal from the K3 to the KPA when 
using the Icom. Otherwise you may be able to leave the AuxIO cable connected.
I know that Fred Cady discussed sharing a KPA between two radios in his book, 
but has anyone solved this situation - one radio is a K3, the other something 
else?

73,
Jack, W6FB

> On Mar 31, 2022, at 9:11 PM, James Bennett via Elecraft 
>  wrote:
> 
> Bob -
> 
> The * appears when I key the K3 and the amp is in operate mode. Likewise if I 
> key the 705 and the amp is in operate mode, with the K3 powered on.
> 
> If I power off the K3 and place the amp in operate mode WITHOUT KEYING IT, 
> the * appears, so you are correct - the amp thinks it is being keyed.
> 
> There is a jack on the 705 that allows one to key an external amp. I have 
> that line running to the amp. Disconnecting it makes no difference the * 
> appears as soon as I put the amp into operate mode. If I power on the K3, 
> this does not happen. However, with the K3 powered on and that cable 
> disconnected, the amp does not key at all, so it is working as expected - but 
> only with the K3 powered on. Somewhere the K3 is getting its foot in the door 
> when powered off…
> 
> Jim / K7TXA
> 
> 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”??
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Re: [Elecraft] KPA500 Issue

[Jack Brindle via Elecraft]

The reason I don’t suspect the PIN diodes is that the KPA works properly with 
the K3. The K3 does not have a magical ability to repair KPA PIN diodes, so it 
most likely is not a problem there.

This is probably a K3 without the new K3S I/O board, which means it has pull-up 
resistors on the BAND lines. When the K3 is powered off it pulls those lines 
down, which is the same as 60 meters.
But, it will only change the band one time in this situation. 

My biggest curiosity is why unplugging the AuxIO cable will cause the KPA to 
not go into OPER mode. There must be something else connected for this to 
happen. Jim, you might try unplugging the cable from the back of the KPA to 
test this. Once we have that working, we can move on from there. And perhaps 
find a way to get our direct email path working again...

73,
Jack, W6FB


> On Mar 31, 2022, at 5:39 PM, Andy Durbin  wrote:
> 
> "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 failure of 
> the TR switch PIN diodes.  Jack's idea of incorrect band can be easily 
> confirmed, or eliminated, by looking at the KPA500 band display.
> 
> Andy, k3wyc
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Re: [Elecraft] KPA500 Issue

[Jack Brindle via Elecraft]

The email I sent earlier. You might look in your junk folder, Jim…

73,
Jack, W6FB


> From: Jack Brindle 
> Subject: Re: KPA500 Issue
> Date: March 31, 2022 at 2:40:26 PM CDT
> To: James Bennett 
> 
> On the KPA front panel, hold the menu button to go into the menus, then 
> scroll down to the RADIO setting.
> 
> I’m contemplating why the KPA won’t go into OPER with the AuxIO cable 
> installed. That doesn’t make sense. What version of firmware do you have 
> installed? The KPA menu has a firmware selection that displays the version.



> On Mar 31, 2022, at 7:00 PM, James Bennett via Elecraft 
>  wrote:
> 
> I was unable to try Jack’s suggestion of disconnecting the AUXIO cable - 
> doing so made the KPA5000 not able to go into Operate mode. So, I wanted to 
> do the other option he mentioned - changing the “radio” setting of the KPA to 
> Serial or Analog. Unfortunately, I have no idea where that setting is. It 
> isn’t in my version of the KPA Utility: V1.19.9.6. I sent Jack an email about 
> it but he’s evidently off-line. Anyidea where that setting might be found?
> 
> My KPA shows the correct band on its display. The failure ONLY happens with 
> the K3 powered off. When it is powered up and set to the correct band, the 
> audio level in the IC-705 does not change when switching the amp from operate 
> to standby.
> 
> Jim / K7TXA
> 
>> On Mar 31, 2022, at 4:39 PM, Andy Durbin > > wrote:
>> 
>> "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 failure of 
>> the TR switch PIN diodes. Jack's idea of incorrect band can be easily 
>> confirmed, or eliminated, by looking at the KPA500 band display.
>> 
>> Andy, k3wyc
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Re: [Elecraft] KPA500 Issue

[Andy Durbin]

"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

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Re: [Elecraft] KPA500 Issue

[James Bennett via Elecraft]

Bob -

The * appears when I key the K3 and the amp is in operate mode. Likewise if I 
key the 705 and the amp is in operate mode, with the K3 powered on.

If I power off the K3 and place the amp in operate mode WITHOUT KEYING IT, the 
* appears, so you are correct - the amp thinks it is being keyed.

There is a jack on the 705 that allows one to key an external amp. I have that 
line running to the amp. Disconnecting it makes no difference the * appears as 
soon as I put the amp into operate mode. If I power on the K3, this does not 
happen. However, with the K3 powered on and that cable disconnected, the amp 
does not key at all, so it is working as expected - but only with the K3 
powered on. Somewhere the K3 is getting its foot in the door when powered off…

Jim / K7TXA

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”??
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Re: [Elecraft] KPA500 Issue

[kd4iz]

Jim, All,

James Bennett Wrote:

> 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. I 
> also notice that the amp fan doesn?t take too long to crank up to high speed, 
> and the PA temp is sitting around 67 C.

I occasionally use an IC-705 to drive either a KXPA100, a KPA500/KAT500 pair, 
or both in cascade. I have a keyline splitter (the one for the KX3 to the KXPA) 
that allows me to cascade the KXPA100 to the KPA500. 

After I accidentally popped ~100W into the input of the KPA500 while 
experimenting with the switching arrangement, my system suddenly had the 
identical problem Jim describes, a much attenuated signal on receive and normal 
transmit. It was R9. Taking the amp apart was much more involved than replacing 
the resistor. I found R9 split in two and the two halves standing (yes, really) 
on the solder pads. (photo available on request).

The very kind folk at the mothership sent me a replacement for R9, a surface 
mount 50 ohm resistor, and it was an easy repair. I have everything set up with 
switching so I don't do it again. 

Now, when I put the IC-705 into the "cascade" mix, I set the rig output power 
to 5% which results in a 25-30W output from the KXPA100. 30W will drive the 
KPA500 to full power. I also use a sequential check list every time I bring the 
IC-705 into the shack to avoid the uncomfortable "oops" moment again. 

Note: make sure that the keyline that goes to the IC-705 has a 480 ohm resistor 
in series with the keyline jack tip when using a KXPA100... without it you 
can't use the IC-705 voice memories or the "DV TX Message" data in DR/DV mode 
without having the rig lock up in a transmit key up loop. The series resistor 
seems to have no effect on the ability of the 705 to key the KPA500. Please ask 
me offline if you have any additional questions about this setup. It has been 
stable and predictable ever since the repair was done 2 years back.

Jack Spitznagel – KD4IZ
kd...@arrl.net






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[Elecraft] KPA500 Issue

[Bob McGraw]

Are you seeing and * on the KPA500 screen when using the IC-705 and the 
amp is in Operate mode?   If so, the amp is being keyed while the IC-705 
is in receive mode.  Confirmed by the fact when the amp is in STBY that 
signals are normal.


Check your amp keying interface and cable wiring.  You should be able to 
prove and Amp Key command from the IC-705 to the KPA500. Thus when the 
IC-705 is keyed, likewise the amp.


73

Bob, K4TAX




On 3/31/2022 6:35 PM, elecraft-requ...@mailman.qth.net wrote:

Message: 17
Date: Thu, 31 Mar 2022 11:52:29 -0600
From: James Bennett
To: Elecraft Reflector Reflector
Subject: [Elecraft] KPA500 Issue
Message-ID:
Content-Type: text/plain;   charset=utf-8

Having an issue with my KPA500 and a non-elecraft radio. I?ve got an Icom 
IC-705 connected to my KPA500 and KAT500. By dropping the 705?s output power to 
4 watts and pressing Tune on the KAT500 with the amp in OPER mode, I?m able to 
get the tuner to give me a good match on just about all bands to my Zerofive 
Flagpole Vertical. Then, turning the power level up to max (10 watts) on the 
IC-705, the amp gives me anywhere from 210 to 250 watts output, depending on 
the band. And that?s fine for me right now.

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. I also 
notice that the amp fan doesn?t take too long to crank up to high speed, and 
the PA temp is sitting around 67 C.

I also have a K3. When I power up the K3 and switch the antenna over to the K3 
on the same band as the IC-705 - there is no drop in signal level on it when 
switching between OPER and STBY on the amp. And, yes, when I?m using the 
IC-705, I press the corresponding BAND button on the amp.

OK - some further info: if I have the K3 sitting on the same band as the IC-705 
this does not happen - going from STBY to OPER on the amp makes no difference 
on receive level on the IC-705. But if I power off the K3, the IC-705 reverts 
to its partially-deaf state.

Somewhere long ago in a far distant galaxy, I recall Jack W6FB mentioning that 
the K3 pulls some signal to zero when it is powered off. I suspect that may be 
what is happening here but for the life of me I can?t recall the exact 
conversation. I?d like to get to the point where I can run the IC-705 with this 
tuner and amp without having the K3 in the equation, as the K3 will be going on 
the sale block in the near future, in anticipation of a K4D delivery.

Any ideas?  Jack - are you listening?:-)

Jim / K7TXA


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[Elecraft] KPA500 Issue

[Bob McGraw]

Are you seeing and * on the KPA500 screen when using the IC-705 and the 
amp is in Operate mode?   If so, the amp is being keyed while the IC-705 
is in receive mode.  Confirmed by the fact when the amp is in STBY that 
signals are normal.


Check your amp keying interface and cable wiring.  You should be able to 
prove and Amp Key command from the IC-705 to the KPA500. Thus when the 
IC-705 is keyed, likewise the amp.


73

Bob, K4TAX




On 3/31/2022 6:35 PM, elecraft-requ...@mailman.qth.net wrote:

Message: 17
Date: Thu, 31 Mar 2022 11:52:29 -0600
From: James Bennett
To: Elecraft Reflector Reflector
Subject: [Elecraft] KPA500 Issue
Message-ID:
Content-Type: text/plain;   charset=utf-8

Having an issue with my KPA500 and a non-elecraft radio. I?ve got an Icom 
IC-705 connected to my KPA500 and KAT500. By dropping the 705?s output power to 
4 watts and pressing Tune on the KAT500 with the amp in OPER mode, I?m able to 
get the tuner to give me a good match on just about all bands to my Zerofive 
Flagpole Vertical. Then, turning the power level up to max (10 watts) on the 
IC-705, the amp gives me anywhere from 210 to 250 watts output, depending on 
the band. And that?s fine for me right now.

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. I also 
notice that the amp fan doesn?t take too long to crank up to high speed, and 
the PA temp is sitting around 67 C.

I also have a K3. When I power up the K3 and switch the antenna over to the K3 
on the same band as the IC-705 - there is no drop in signal level on it when 
switching between OPER and STBY on the amp. And, yes, when I?m using the 
IC-705, I press the corresponding BAND button on the amp.

OK - some further info: if I have the K3 sitting on the same band as the IC-705 
this does not happen - going from STBY to OPER on the amp makes no difference 
on receive level on the IC-705. But if I power off the K3, the IC-705 reverts 
to its partially-deaf state.

Somewhere long ago in a far distant galaxy, I recall Jack W6FB mentioning that 
the K3 pulls some signal to zero when it is powered off. I suspect that may be 
what is happening here but for the life of me I can?t recall the exact 
conversation. I?d like to get to the point where I can run the IC-705 with this 
tuner and amp without having the K3 in the equation, as the K3 will be going on 
the sale block in the near future, in anticipation of a K4D delivery.

Any ideas?  Jack - are you listening?:-)

Jim / K7TXA


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Re: [Elecraft] KPA500 Issue

[Lyle Johnson]

Jim,
See page 38 of the Rev E1 KPA500 operating manual for how to set the radio
in the KPA500 menu (not KPA500 utility).  This is the current version of
the manual a available on the Elecraft website.
73,
Lyle Kk7P

On Thu, Mar 31, 2022 at 5:12 PM Jim Clymer  wrote:

> In my case, it was not the PIN diodes themselves, but failure of R9. I'm
> away from my shack right now, so may not have the resistor ID correct. It
> is a 48 Ohm resistor. I fixed the problem by parallel connecting a pair of
> 1/4 W, 100 Ohm resistors across the open one. Problem solved. Been fine
> since.
> There is documentation of this problem. A German ham wrote to me with a
> link to the solution. If no one steps forward before tomorrow, I'll try to
> post the info in the morning.
> 73,
> Jim -  WS6X
>
> On Thu, Mar 31, 2022, 6:40 PM Andy Durbin  wrote:
>
> > "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 failure
> > of the TR switch PIN diodes.  Jack's idea of incorrect band can be easily
> > confirmed, or eliminated, by looking at the KPA500 band display.
> >
> > Andy, k3wyc
> >
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Re: [Elecraft] KPA500 Issue

[Jim Clymer]

In my case, it was not the PIN diodes themselves, but failure of R9. I'm
away from my shack right now, so may not have the resistor ID correct. It
is a 48 Ohm resistor. I fixed the problem by parallel connecting a pair of
1/4 W, 100 Ohm resistors across the open one. Problem solved. Been fine
since.
There is documentation of this problem. A German ham wrote to me with a
link to the solution. If no one steps forward before tomorrow, I'll try to
post the info in the morning.
73,
Jim -  WS6X

On Thu, Mar 31, 2022, 6:40 PM Andy Durbin  wrote:

> "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 failure
> of the TR switch PIN diodes.  Jack's idea of incorrect band can be easily
> confirmed, or eliminated, by looking at the KPA500 band display.
>
> Andy, k3wyc
>
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Re: [Elecraft] KPA500 Issue

[James Bennett via Elecraft]

I was unable to try Jack’s suggestion of disconnecting the AUXIO cable - doing 
so made the KPA5000 not able to go into Operate mode. So, I wanted to do the 
other option he mentioned - changing the “radio” setting of the KPA to Serial 
or Analog. Unfortunately, I have no idea where that setting is. It isn’t in my 
version of the KPA Utility: V1.19.9.6. I sent Jack an email about it but he’s 
evidently off-line. Anyidea where that setting might be found?

My KPA shows the correct band on its display. The failure ONLY happens with the 
K3 powered off. When it is powered up and set to the correct band, the audio 
level in the IC-705 does not change when switching the amp from operate to 
standby.

Jim / K7TXA

> On Mar 31, 2022, at 4:39 PM, Andy Durbin  wrote:
> 
> "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 failure of 
> the TR switch PIN diodes.  Jack's idea of incorrect band can be easily 
> confirmed, or eliminated, by looking at the KPA500 band display.
> 
> Andy, k3wyc
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Re: [Elecraft] KPA500 Issue

[Andy Durbin]

"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 failure of the 
TR switch PIN diodes.  Jack's idea of incorrect band can be easily confirmed, 
or eliminated, by looking at the KPA500 band display.

Andy, k3wyc
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Re: [Elecraft] KPA500 Issue

[Jack Brindle via Elecraft]

m;

What happens when you disconnect the AuxIO cable from the K3 to the KPA? The 
other solution is to switch the RADIO setting of the KPA from K3 to something 
else, either Serial or Analog. If nothing is connected to the analog band input 
with RADIO = ANALOG, the KPA should work as usual. Likewise if nothing is 
connected to the “Radio” serial port with RADIO=“SERIAL” then it should work 
just fine, but no automatic band selection will occur.

It sounds like the K3 is overriding the front panel selection, keeping the 
KPA’s low pass filters on a band that is not the one you desire for the IC-705.

Let me know if this helps.

73m,
Jack, W6FB


> On Mar 31, 2022, at 12:52 PM, James Bennett via Elecraft 
>  wrote:
> 
> Having an issue with my KPA500 and a non-elecraft radio. I’ve got an Icom 
> IC-705 connected to my KPA500 and KAT500. By dropping the 705’s output power 
> to 4 watts and pressing Tune on the KAT500 with the amp in OPER mode, I’m 
> able to get the tuner to give me a good match on just about all bands to my 
> Zerofive Flagpole Vertical. Then, turning the power level up to max (10 
> watts) on the IC-705, the amp gives me anywhere from 210 to 250 watts output, 
> depending on the band. And that’s fine for me right now.
> 
> 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. I 
> also notice that the amp fan doesn’t take too long to crank up to high speed, 
> and the PA temp is sitting around 67 C. 
> 
> I also have a K3. When I power up the K3 and switch the antenna over to the 
> K3 on the same band as the IC-705 - there is no drop in signal level on it 
> when switching between OPER and STBY on the amp. And, yes, when I’m using the 
> IC-705, I press the corresponding BAND button on the amp.
> 
> OK - some further info: if I have the K3 sitting on the same band as the 
> IC-705 this does not happen - going from STBY to OPER on the amp makes no 
> difference on receive level on the IC-705. But if I power off the K3, the 
> IC-705 reverts to its partially-deaf state.
> 
> Somewhere long ago in a far distant galaxy, I recall Jack W6FB mentioning 
> that the K3 pulls some signal to zero when it is powered off. I suspect that 
> may be what is happening here but for the life of me I can’t recall the exact 
> conversation. I’d like to get to the point where I can run the IC-705 with 
> this tuner and amp without having the K3 in the equation, as the K3 will be 
> going on the sale block in the near future, in anticipation of a K4D 
> delivery. 
> 
> Any ideas?  Jack - are you listening? :-)
> 
> Jim / K7TXA
> 
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[Elecraft] KPA500 Issue

[James Bennett via Elecraft]

Having an issue with my KPA500 and a non-elecraft radio. I’ve got an Icom 
IC-705 connected to my KPA500 and KAT500. By dropping the 705’s output power to 
4 watts and pressing Tune on the KAT500 with the amp in OPER mode, I’m able to 
get the tuner to give me a good match on just about all bands to my Zerofive 
Flagpole Vertical. Then, turning the power level up to max (10 watts) on the 
IC-705, the amp gives me anywhere from 210 to 250 watts output, depending on 
the band. And that’s fine for me right now.

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. I also 
notice that the amp fan doesn’t take too long to crank up to high speed, and 
the PA temp is sitting around 67 C. 

I also have a K3. When I power up the K3 and switch the antenna over to the K3 
on the same band as the IC-705 - there is no drop in signal level on it when 
switching between OPER and STBY on the amp. And, yes, when I’m using the 
IC-705, I press the corresponding BAND button on the amp.

OK - some further info: if I have the K3 sitting on the same band as the IC-705 
this does not happen - going from STBY to OPER on the amp makes no difference 
on receive level on the IC-705. But if I power off the K3, the IC-705 reverts 
to its partially-deaf state.

Somewhere long ago in a far distant galaxy, I recall Jack W6FB mentioning that 
the K3 pulls some signal to zero when it is powered off. I suspect that may be 
what is happening here but for the life of me I can’t recall the exact 
conversation. I’d like to get to the point where I can run the IC-705 with this 
tuner and amp without having the K3 in the equation, as the K3 will be going on 
the sale block in the near future, in anticipation of a K4D delivery. 

Any ideas?  Jack - are you listening? :-)

Jim / K7TXA

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Re: [Elecraft] KPA500 issue

[Bill Frantz]

I think you have enough information to order a replacement from Elecraft.

73 Bill AE6JV

On 11/9/20 at 3:55 PM, kb2mj...@att.net wrote:

> I had a capacitor fail in my KPA500's 15m  bank pass filter area. It is C151
> a 100pf capacitor. Does anyone know what physical size it is, so I can order
> one ? Thanks
> 
> 73 Jeff kb2m


Bill Frantz|"Insofar as the propositions of mathematics refer to
408-348-7900   | reality, they are not certain; and insofar they are
www.pwpconsult.com | certain, they do not refer to reality.” -- Einstein

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[Elecraft] KPA500 issue

[kb2mjeff]

I had a capacitor fail in my KPA500's 15m  bank pass filter area. It is C151
a 100pf capacitor. Does anyone know what physical size it is, so I can order
one ? Thanks

73 Jeff kb2m

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Re: [Elecraft] KPA500 Issue

[Andrew Faber]

Yes, that was the problem when it happened to me.  It was a cable problem 
that was inadvertently closing the key in (PA Key) input on the back of 
the KPA500.  Clearing that up restored normal operation.

73, andy ae6y
-Original Message- 
From: Mike K2MK

Sent: Friday, January 30, 2015 5:34 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Issue

Hi Barry,

There is an asterisk that appears on the left side of the KPA500 display
whenever the key out signal from your transmitter is present. You should not
see the asterisk when you are receiving. If you are then is it possible that
you are using the key out signal to operate some other device in addition to
the KPA500?

73,
Mike K2MK


Barry Simpson wrote

My KPA500 has just developed an issue. Specifically when I switch it from
Stby to Oper, the level of received signals drops by around 5 or 6 s
points. It still transmits fine and there are no adverse SWR indications
or
loose co-ax plugs. It does the same on all bands. I switch back to Stby
and
the received signals return to normal.

I seem to recall that someone else posted details of a similar such
problem
some time ago. Any suggestions would be helpful before I email the
Elecraft
hot line.

Barry Simpson   VK2BJ






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Re: [Elecraft] KPA500 Issue

[Mike K2MK]

Hi Barry,

While your experience suggests that a transistor switch will probably save
the day I also wonder if the problem is the result of the absence or
presence of a pull-up resistor or perhaps a floating common connection
between the rig and amp. Maybe a resistor in the plug would help. I suppose
there is some way to check this out.

73,
Mike K2MK


Barry Simpson wrote
 .partial quote from Barry..
 The conclusion is therefore that from an initial OK position in Stby and
 Oper as soon as the first character is keyed, the solid state switch in
 the
 TS590SG hangs resulting in the KPA500 being permanently in the transmit
 state. The situation only clears when rig and amp are turned off, the Din
 plug is removed from the TS590SG and reinserted and both are turned back
 on. I can then switch the amp back to Oper and all is fine until the very
 first morse character when it all happens again.  So as it stands, there
 appears to be incompatibility between the TS590SG solid state amp switch
 and KPA500.
 
 As an interim measure, I have rewired the Din plug to use the noisy relay
 for the amp control and that works fine. The TS590SG does output 12V to
 the
 solid state switching pin in certain configurations as did the TS590S. I
 had a TS590S and I wired a single transistor solid state switch inside the
 Din plug and that worked perfectly so I am going to do the same again,
 which should solve the issue. Unfortunately, I gave away the TS590S cable
 I
 had made up to the guy I sold the TS590S to. I never got the very bad
 spike
 issue fixed but the buyer did not mind as he doesn't use a linear.
 
 It really is a pity as I thought that the new linear switching circuitry
 in
 the TS590SG was a real step forward but it is not to be, at least not with
 the KPA500.
 
 73
 Barry  VK2BJ





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Re: [Elecraft] KPA500 Issue

[AG0N-3055]

  when I switch it from
 Stby to Oper, the level of received signals drops by around 5 or 6 s
 points. It still transmits fine and there are no adverse SWR indications or
 loose co-ax plugs. It does the same on all bands.

Sounds like bad PIN DIODE situation, but I'll let those who are more
expert at them take that on.

 I switch back to Stby and the received signals return to normal.

Just for reference, on six meters, using WSJT10 for FSK441 MS, I see one
db drop in my JT measured band (white) noise between the KPA STBY and
OPER modes.

Gary
-- 
http://ag0n.net
3055: http://ag0n.net/irlp/3055
NodeOp Help Page: http://ag0n.net/irlp
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Re: [Elecraft] KPA500 Issue

[Joe Hutchens AJ8MH-Radio]

Looks like the Kenwood switches high during transmit and the KPA500 
requires a low for transmit. KPA500 specs in my manual say +5V max, open 
circuit on receive, closed to ground on transmit.  My old KPA500 manual 
doesn't show Kenwood interconnections.  Only the K3, Yaesu and Icom.


Yup, ya need to supply a low to the amp.

Joe ( AJ8MH )
http://webpages.charter.net/aj8mh-radio/



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Re: [Elecraft] KPA500 Issue

[Barry Simpson]

Good morning to those who responded to me on the Elecraft reflector. Here
is the interim outcome.

I did not mention that the problem arose after connecting my brand new
(yesterday) TS590SG to the KPA500.  The TS590SG has different linear
switching facilities from the TS590S in that there is now provision for
solid state switching to avoid a clicking relay. I was using the solid
state switching set up. I use the same set up with my TS990S and that works
perfectly with the KPA500.

I checked and resoldered the connecting cable and then I interchanged the
cable I use with the TS990S as the Din pin connections are identitical with
the TS590SG. The outcome was exactly the same with the loss of received
signals when the KPA500 is switched to Oper and the little asterisk appears
on the left side of the display. However, the set up still keys the KPA500
perfectly.

I then changed over to the TS990S and with that rig, the KPA500 works
perfectly with the solid state switching.

The conclusion is therefore that from an initial OK position in Stby and
Oper as soon as the first character is keyed, the solid state switch in the
TS590SG hangs resulting in the KPA500 being permanently in the transmit
state. The situation only clears when rig and amp are turned off, the Din
plug is removed from the TS590SG and reinserted and both are turned back
on. I can then switch the amp back to Oper and all is fine until the very
first morse character when it all happens again.  So as it stands, there
appears to be incompatibility between the TS590SG solid state amp switch
and KPA500.

As an interim measure, I have rewired the Din plug to use the noisy relay
for the amp control and that works fine. The TS590SG does output 12V to the
solid state switching pin in certain configurations as did the TS590S. I
had a TS590S and I wired a single transistor solid state switch inside the
Din plug and that worked perfectly so I am going to do the same again,
which should solve the issue. Unfortunately, I gave away the TS590S cable I
had made up to the guy I sold the TS590S to. I never got the very bad spike
issue fixed but the buyer did not mind as he doesn't use a linear.

It really is a pity as I thought that the new linear switching circuitry in
the TS590SG was a real step forward but it is not to be, at least not with
the KPA500.

For information and to avoid others having a similar head scratching issue,
I am copying this to the TS590 list as well. As a final point, I can
confirm that the TS590SG has no power spike issue whatsoever and the
average audio level in SSB seems much improved from the TS590S.

Once I have wired and implemented the transistor switch, I will report back
with the result.

73

Barry  VK2BJ

On 31 January 2015 at 00:34, Mike K2MK k...@comcast.net wrote:

 Hi Barry,

 There is an asterisk that appears on the left side of the KPA500 display
 whenever the key out signal from your transmitter is present. You should
 not
 see the asterisk when you are receiving. If you are then is it possible
 that
 you are using the key out signal to operate some other device in addition
 to
 the KPA500?

 73,
 Mike K2MK


 Barry Simpson wrote
  My KPA500 has just developed an issue. Specifically when I switch it from
  Stby to Oper, the level of received signals drops by around 5 or 6 s
  points. It still transmits fine and there are no adverse SWR indications
  or
  loose co-ax plugs. It does the same on all bands. I switch back to Stby
  and
  the received signals return to normal.
 
  I seem to recall that someone else posted details of a similar such
  problem
  some time ago. Any suggestions would be helpful before I email the
  Elecraft
  hot line.
 
  Barry Simpson   VK2BJ





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[Elecraft] KPA500 Issue

[Barry Simpson]

My KPA500 has just developed an issue. Specifically when I switch it from
Stby to Oper, the level of received signals drops by around 5 or 6 s
points. It still transmits fine and there are no adverse SWR indications or
loose co-ax plugs. It does the same on all bands. I switch back to Stby and
the received signals return to normal.

I seem to recall that someone else posted details of a similar such problem
some time ago. Any suggestions would be helpful before I email the Elecraft
hot line.

Barry Simpson   VK2BJ
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Re: [Elecraft] KPA500 Issue

[Mike K2MK]

Hi Barry,

There is an asterisk that appears on the left side of the KPA500 display
whenever the key out signal from your transmitter is present. You should not
see the asterisk when you are receiving. If you are then is it possible that
you are using the key out signal to operate some other device in addition to
the KPA500?

73,
Mike K2MK


Barry Simpson wrote
 My KPA500 has just developed an issue. Specifically when I switch it from
 Stby to Oper, the level of received signals drops by around 5 or 6 s
 points. It still transmits fine and there are no adverse SWR indications
 or
 loose co-ax plugs. It does the same on all bands. I switch back to Stby
 and
 the received signals return to normal.
 
 I seem to recall that someone else posted details of a similar such
 problem
 some time ago. Any suggestions would be helpful before I email the
 Elecraft
 hot line.
 
 Barry Simpson   VK2BJ





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