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K2: Flaky 160M switching

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Jim KO5V

K2: Flaky 160M switching

After removing and replacing the heatsink panel to install an SMA connector for an IF-out port,
160M is working intermittently. I think I have narrowed it down to a problem with the antenna's
BNC connector - It appears to be just slightly spaced away from the inside of the back panel,
so when its nut is tightened up, it must be flexing the RF board enough to affect K8. I've loosened
up the 2d connectors, to try and bring the connector/RF board into better alignment with the heatsink
panel, but every time I tighten up the BNC's nut, 160 eventually dies (I listen to the birdie at 2Mhz).

When I switch from a working 160M to 80M and then "tune", 80M gives a "hi-Current" error, and I
measure >20W on my external meter. A second "tune", and 80M is back to normal. Switching back to 160M,
I find the birdie gone (and no power out). Switching to 160M from a higher-frequency band usually finds 160M
working (but not always).

I have touched up the solder joints on all components involved with K8 and the BNC on the RF board, and all
of the joints on the 160M board.

So, I am going to place a shim between the BNC connector, and the heatsink panel and see what happens. Does
anyone have any other suggestions? I'm not sure K8 is bad, but maybe the BNC might be?

Thanks in advance. 73,

Jim KO5V

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Don Wilhelm

Re: K2: Flaky 160M switching

Jim,

Loosen the nut on the BNC connector or remove it entirely. Since the
BNC jack is soldered to the board, the nut is only there for "pretty"
All will work fine without the nut. The nut in any case should only be
a bit more than finger tight. "Beefing" the nut up tight can damage the
BNC connector (same for the key jack).

Yes, tightening the nut up tight is likely bending the RF Board.

Check for the possibility that the rear panel is bent a bit in the
vicinity of the hole for the BNC jack.

As for the high current on 80 meters after moving from a non-functioning
160 meters, that is not unusual. The Drive to the RF Chain is maxed out
on 160 and when you move to 80, it will not be reset with a TUNE -
normal keying or speech will quickly correct it, but not TUNE until you
exit and re-enter TUNE.

73,
Don W3FPR

On 3/2/2019 2:30 PM, Jim KO5V wrote:

> After removing and replacing the heatsink panel to install an SMA connector for an IF-out port,
> 160M is working intermittently. I think I have narrowed it down to a problem with the antenna's
> BNC connector - It appears to be just slightly spaced away from the inside of the back panel,
> so when its nut is tightened up, it must be flexing the RF board enough to affect K8. I've loosened
> up the 2d connectors, to try and bring the connector/RF board into better alignment with the heatsink
> panel, but every time I tighten up the BNC's nut, 160 eventually dies (I listen to the birdie at 2Mhz).
>
> When I switch from a working 160M to 80M and then "tune", 80M gives a "hi-Current" error, and I
> measure >20W on my external meter. A second "tune", and 80M is back to normal. Switching back to 160M,
> I find the birdie gone (and no power out). Switching to 160M from a higher-frequency band usually finds 160M
> working (but not always).
>
> I have touched up the solder joints on all components involved with K8 and the BNC on the RF board, and all
> of the joints on the 160M board.
>
> So, I am going to place a shim between the BNC connector, and the heatsink panel and see what happens. Does
> anyone have any other suggestions? I'm not sure K8 is bad, but maybe the BNC might be?

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html

Jim KO5V

Re: K2: Flaky 160M switching

In reply to this post by Jim KO5V

Thanks Don,

With the nut loose, it is much less intermittent. When it does hang up, a tap on the back of the left side panel
causes the 2Mhz birdie to return, so I think I'll order a replacement for K8 just in case it's been damaged.

With hands like catcher's mitts,"Beefing" fasteners is always an issue for me...

The 80M high current behavior I observed is exactly what you describe.

73, Jim KO5V

-----Original Message-----

>From: Don Wilhelm <[hidden email]>
>Sent: Mar 2, 2019 1:04 PM
>To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>Subject: Re: [Elecraft] K2: Flaky 160M switching
>
>Jim,
>
>Loosen the nut on the BNC connector or remove it entirely. Since the
>BNC jack is soldered to the board, the nut is only there for "pretty"
>All will work fine without the nut. The nut in any case should only be
>a bit more than finger tight. "Beefing" the nut up tight can damage the
>BNC connector (same for the key jack).
>
>Yes, tightening the nut up tight is likely bending the RF Board.
>
>Check for the possibility that the rear panel is bent a bit in the
>vicinity of the hole for the BNC jack.
>
>As for the high current on 80 meters after moving from a non-functioning
>160 meters, that is not unusual. The Drive to the RF Chain is maxed out
>on 160 and when you move to 80, it will not be reset with a TUNE -
>normal keying or speech will quickly correct it, but not TUNE until you
>exit and re-enter TUNE.
>
>73,
>Don W3FPR
>
>On 3/2/2019 2:30 PM, Jim KO5V wrote:
>> After removing and replacing the heatsink panel to install an SMA connector for an IF-out port,
>> 160M is working intermittently. I think I have narrowed it down to a problem with the antenna's
>> BNC connector - It appears to be just slightly spaced away from the inside of the back panel,
>> so when its nut is tightened up, it must be flexing the RF board enough to affect K8. I've loosened
>> up the 2d connectors, to try and bring the connector/RF board into better alignment with the heatsink
>> panel, but every time I tighten up the BNC's nut, 160 eventually dies (I listen to the birdie at 2Mhz).
>>
>> When I switch from a working 160M to 80M and then "tune", 80M gives a "hi-Current" error, and I
>> measure >20W on my external meter. A second "tune", and 80M is back to normal. Switching back to 160M,
>> I find the birdie gone (and no power out). Switching to 160M from a higher-frequency band usually finds 160M
>> working (but not always).
>>
>> I have touched up the solder joints on all components involved with K8 and the BNC on the RF board, and all
>> of the joints on the 160M board.
>>
>> So, I am going to place a shim between the BNC connector, and the heatsink panel and see what happens. Does
>> anyone have any other suggestions? I'm not sure K8 is bad, but maybe the BNC might be?

Don Wilhelm

Re: K2: Flaky 160M switching

Jim,

Replacing K8 is not going to do anything for 160 meters. The relay that
switches in the 160 meter low pass filter is K1 on the K160RX board.

Try this the next time it happens - while on 160 meters, change the
antenna to the RX ANT jack and set the RX ANT menu parameter to ON. See
if you obtain receive. The RX ANT bypasses the Low Pass Filter.

You may have a poor solder connection on the K160RX board or its header.

73,
Don W3FPR

On 3/2/2019 3:28 PM, Jim KO5V wrote:

> Thanks Don,
>
> With the nut loose, it is much less intermittent. When it does hang up, a tap on the back of the left side panel
> causes the 2Mhz birdie to return, so I think I'll order a replacement for K8 just in case it's been damaged.
>
> With hands like catcher's mitts,"Beefing" fasteners is always an issue for me...
>
> The 80M high current behavior I observed is exactly what you describe.
>
> 73, Jim KO5V
>
> -----Original Message-----
>> From: Don Wilhelm <[hidden email]>
>> Sent: Mar 2, 2019 1:04 PM
>> To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>> Subject: Re: [Elecraft] K2: Flaky 160M switching
>>
>> Jim,
>>
>> Loosen the nut on the BNC connector or remove it entirely. Since the
>> BNC jack is soldered to the board, the nut is only there for "pretty"
>> All will work fine without the nut. The nut in any case should only be
>> a bit more than finger tight. "Beefing" the nut up tight can damage the
>> BNC connector (same for the key jack).
>>
>> Yes, tightening the nut up tight is likely bending the RF Board.
>>
>> Check for the possibility that the rear panel is bent a bit in the
>> vicinity of the hole for the BNC jack.
>>
>> As for the high current on 80 meters after moving from a non-functioning
>> 160 meters, that is not unusual. The Drive to the RF Chain is maxed out
>> on 160 and when you move to 80, it will not be reset with a TUNE -
>> normal keying or speech will quickly correct it, but not TUNE until you
>> exit and re-enter TUNE.
>>
>> 73,
>> Don W3FPR
>>
>> On 3/2/2019 2:30 PM, Jim KO5V wrote:
>>> After removing and replacing the heatsink panel to install an SMA connector for an IF-out port,
>>> 160M is working intermittently. I think I have narrowed it down to a problem with the antenna's
>>> BNC connector - It appears to be just slightly spaced away from the inside of the back panel,
>>> so when its nut is tightened up, it must be flexing the RF board enough to affect K8. I've loosened
>>> up the 2d connectors, to try and bring the connector/RF board into better alignment with the heatsink
>>> panel, but every time I tighten up the BNC's nut, 160 eventually dies (I listen to the birdie at 2Mhz).
>>>
>>> When I switch from a working 160M to 80M and then "tune", 80M gives a "hi-Current" error, and I
>>> measure >20W on my external meter. A second "tune", and 80M is back to normal. Switching back to 160M,
>>> I find the birdie gone (and no power out). Switching to 160M from a higher-frequency band usually finds 160M
>>> working (but not always).
>>>
>>> I have touched up the solder joints on all components involved with K8 and the BNC on the RF board, and all
>>> of the joints on the 160M board.
>>>
>>> So, I am going to place a shim between the BNC connector, and the heatsink panel and see what happens. Does
>>> anyone have any other suggestions? I'm not sure K8 is bad, but maybe the BNC might be?

Jim KO5V

Re: K2: Flaky 160M switching

In reply to this post by Jim KO5V

Don,

Switching to the RX antenna has no effect. The only thing that seems to work is a tap on the back
of the left side panel, at about the 2d connector. That causes the 2Mhz birdie to return. I've
touched up all of the solder joints on the 160M board, and on J14. Maybe K1 is bad, but I'll look
again for a bad solder joint before going there.

Thanks again. 73,

Jim KO5V

-----Original Message-----

>From: Don Wilhelm <[hidden email]>
>Sent: Mar 2, 2019 1:58 PM
>To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>Subject: Re: [Elecraft] K2: Flaky 160M switching
>
>Jim,
>
>Replacing K8 is not going to do anything for 160 meters. The relay that
>switches in the 160 meter low pass filter is K1 on the K160RX board.
>
>Try this the next time it happens - while on 160 meters, change the
>antenna to the RX ANT jack and set the RX ANT menu parameter to ON. See
>if you obtain receive. The RX ANT bypasses the Low Pass Filter.
>
>You may have a poor solder connection on the K160RX board or its header.
>
>73,
>Don W3FPR

Don Wilhelm

Re: K2: Flaky 160M switching

Jim,

K1 and the entire 160 meter low pass filter is not in the path for the
RX ANT, so changing K1 will not help.

Remove the top cover (you can operate like that) and tap on things
gently with a pencil eraser to see if you can locate the problem.

73,
Don W3FPR

On 3/2/2019 4:17 PM, Jim KO5V wrote:

> Don,
>
> Switching to the RX antenna has no effect. The only thing that seems to work is a tap on the back
> of the left side panel, at about the 2d connector. That causes the 2Mhz birdie to return. I've
> touched up all of the solder joints on the 160M board, and on J14. Maybe K1 is bad, but I'll look
> again for a bad solder joint before going there.
>
> Thanks again. 73,
>
> Jim KO5V
>
>
> -----Original Message-----
>> From: Don Wilhelm <[hidden email]>
>> Sent: Mar 2, 2019 1:58 PM
>> To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>> Subject: Re: [Elecraft] K2: Flaky 160M switching
>>
>> Jim,
>>
>> Replacing K8 is not going to do anything for 160 meters. The relay that
>> switches in the 160 meter low pass filter is K1 on the K160RX board.
>>
>> Try this the next time it happens - while on 160 meters, change the
>> antenna to the RX ANT jack and set the RX ANT menu parameter to ON. See
>> if you obtain receive. The RX ANT bypasses the Low Pass Filter.
>>
>> You may have a poor solder connection on the K160RX board or its header.
>>
>> 73,
>> Don W3FPR

Jim KO5V

Re: K2: Flaky 160M switching

In reply to this post by Jim KO5V

OK. One thing common to it all that could be affected by the flexing of the RF board, is the J14
connector assembly. It looks like it could be a bit fragile, since it's so tall. I'll check it again,
and then start tapping.

Thanks again Don. 73,

Jim KO5V

-----Original Message-----

>From: Don Wilhelm <[hidden email]>
>Sent: Mar 2, 2019 3:51 PM
>To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>Subject: Re: [Elecraft] K2: Flaky 160M switching
>
>Jim,
>
>K1 and the entire 160 meter low pass filter is not in the path for the
>RX ANT, so changing K1 will not help.
>
>Remove the top cover (you can operate like that) and tap on things
>gently with a pencil eraser to see if you can locate the problem.
>
>73,
>Don W3FPR

Don Wilhelm

Re: K2: Flaky 160M switching

Jim,

Unplug the K160RX and then plug it back in to wipe any oxidation off the
pins. That may or may not help, but is one easy thing to do "just in case".

73,
Don W3FPR

On 3/2/2019 6:23 PM, Jim KO5V wrote:

> OK. One thing common to it all that could be affected by the flexing of the RF board, is the J14
> connector assembly. It looks like it could be a bit fragile, since it's so tall. I'll check it again,
> and then start tapping.
>
> Thanks again Don. 73,
>
> Jim KO5V
>
>
> -----Original Message-----
>> From: Don Wilhelm <[hidden email]>
>> Sent: Mar 2, 2019 3:51 PM
>> To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>> Subject: Re: [Elecraft] K2: Flaky 160M switching
>>
>> Jim,
>>
>> K1 and the entire 160 meter low pass filter is not in the path for the
>> RX ANT, so changing K1 will not help.
>>
>> Remove the top cover (you can operate like that) and tap on things
>> gently with a pencil eraser to see if you can locate the problem.
>>
>> 73,
>> Don W3FPR