[Elecraft] KPA500 Problems Update

[Don Wilhelm]

Mike,

Your Keyout cabling should be from the K3 Keyout to the top KAT500 PTT 
RLY, and then from the bottom KAT500 PTT RLY to the KPA500. That allows 
the KAT500 to disable keying of the KPA500 during a TUNE operation.

To sequentially test the operation of the KEYOUT lines and the cables, 
do the following checks in order - these checks can tell you the failure 
point.  If you can relate that failure point to Elecraft support, you 
should be able to quickly resolve the problem.

You should first verify the operation of the K3 KEYOUT with your 
ohmmeter.  Set the K3 to TX TEST so no RF is produced, then with your 
ohmmeter probes connected between the center of the RCA KEYOUT jack, key 
the K3 - the ohmmeter should go to zero ohms.
Do the same with pin 10 of the DE15 connector (KEYOUT-LP).  If both 
those tests succeed, the K3 KEYOUT is working for both sources.
If either check fails, you have a K3 problem with the KEYOUT signalling.

Now to check the cables and KAT500 operation.  The question to be 
answered is "At what point does the test fail?"  That answer will 
identify the failure point.  Set the KAT500 to AUTO.

Plug the KPAK3AUX cable into the K3 DE15 ACC connector (without the 
keying interrupter) and make the same check between pins 10 and 12 at 
the far end of the cable.  You should get the same zero ohms result - if 
not, the cable is faulty.
You can also check the RCA cable in the same way - at the far end of the 
cable connector check between the center and shell of the RCA connector.

Checking further, plug the KPAK3AUX cable into the KAT500 XCVR DE15 
connector.
Then measure the resistance between pins 10 and 12 of the AMP DE15 
connector.  It should go to zero when the K3 is keyed.
Now do an ATU TUNE from the K3 - the resistance should still be high 
(perhaps infinite).

Plug the RCA cable from the K3 KEYOUT jack into the upper PTT RLY jack 
and measure the resistance at the bottom one.  Again, when the K3 is 
keyed, the resistance should go to zero, but when you do an ATU TUNE it 
should stay high.

If those tests are good, remove the RCA cable from the KAT500 and 
continue the check by plugging the 2nd KPAK3AUX cable into the AMP 
connector on the KAT500.  Check between pins 10 and 12 at the far end of 
the cable.

Then re-install the KEYLINE INTERRUPTER at the K3 and plug in the RCA 
cable from the K3 to KAT500 plus the RCA cable that will go between the 
KAT500 and the KPA500 and make the same checks at the end of the cable 
that would plug into the KPA500, checking that cable.

If you got this far in the testing with no failure, the operation of the 
K3, KAT500 and the cables has been verified for both the K3 KEYOUT 
signal lines.  The only thing left is the KPA500 inputs.

Leave the KEYLINE INTERRUPTER in place and connect the KPAK3AUX cable 
from the KAT500 to the KPA500 and also connect the RCA cable from the 
KAT500 to the KPA500 PA KEY jack.  The KPA500 should go into transmit 
when the K3 is keyed, but not during an ATU TUNE.

Now remove the KEYLINE INTERRUPTER and the 2 RCA cables and repeat the 
test.  The KPA500 should behave as above if its KEYIN-LP input is 
working correctly.

If you have no devices (such as the STEPPIR controller, band decoder, 
etc.) that must listen to the K3 ACC signals, leave the KEYLINE 
INTERRUPTER out as well as the RCA cables and all should be working - 
put the KAT500 back into MAN after retraining the KAT500 to the antenna 
that was selected for the test.

If you DO have something that needs to listen to the K3 PTT, then put 
the KEYLINE INTERRUPTER in place (at the end of the KPAK3AUX cable, not 
directly on the K3 ACC connector) and both RCA cables. You will be using 
the "Y" cable at the K3 ACC connector to be able to connect the K3 ACC 
signals to the external device.

In other words, do NOT use the KPAK3 AUX cable *without* the KEYLINE 
INTERRUPTER along with the RCA cables.

73,
Don W3FPR


On 9/20/2015 4:25 AM, Mike VE3YF wrote:
>
> I have a work around by using the KPAK3AUX Cable from K3--> KAT500 
> -->KPA500 with the Key line inhibitor installed at the K3. I am also 
> running a separate key
> line from the K3 Keyout jack to the KPA500 PA Key jack. (My first 
> keyline cable had a broken shield, so I have replaced it)
>
> Everything seems to work this way, however still have the problem of 
> either the KPAK3AUX cable which does check out ok, Pin 10 is straight 
> thru, while pins 1,6,7,
> and 8 are not hooked up in the cable, verified with multimeter.
>
> The other possibility is that PTT Line of either the K3 or the KPA500 
> AUX Port is not working properly. I just have to figure out which end 
> is at fault. I have tested
> Pin 10 at the K3 and when I key the rig  I see movement on the 
> multimeter , so I am thinking that Pin 10 at the K3 end is working ok. 
> However I have been wrong before.
>