k2 kpa 100 speaker problem

[ve7ymm]

My new kpa100 looks like its working okay except for the top cover plate screw holes not being deep enough.  I guess I will just use some lock washers under the 3/16" screws. No QSOs yet but all seems to check out according to the specs. However, the headphone jack switch that allows the speaker to work quit after about 3 months of use, just like the one on my K1 did. The speaker doesn't work, nor does the external speaker jack, just the headphone jack.  I put in a new one while I had the K2 apart for testing the kpa100, and now it still doesn't work.  Any suggestions on troubleshooting this?  I might add that the headphone volume seems low to me.  I normally have the af and rf gain on all the way.  Should I just give up, and use amplified speakers with the headphone jack?
Mark Mellish, VE7YMM

[Don Wilhelm-4]

  Mark,

3 questions in the same post - let me try them one at a time (they are
not related).

The screws into the heatsink:  Two possibilities exist, 1) the holes are
not drilled deep enough.  To check, remove a screw and check the depth
of the bottom of the hole with a 1/16 inch or smaller diameter tool (a
component lead will do.  The hole should be deeper than the length of
the screw threads.
2) The hole is deep enough, but is not tapped all the way to the
bottom.  If that is the case, then the hole can be tapped deeper with a
4-40 bottom tap (note that is different than a normal tap - a normal tap
will not do the job).  Thirdly, Elecraft can replace the heatsink if you
explain and ask at [hidden email].

No speaker:  Is it possible that you have the speaker wire to the KPA100
plugged in wrong?  The header is P5 on the RF Board - there is a P5 on
the top of the Control Board, but it has no audio on it.  Also,
reversing the wires of the speaker cable in the housing (or at the
soldered connections) will short out the audio.  The ungrounded wire is
on pin 1 of P5.  You can remove the K2 bottom cover and check continuity
between the rear rightmost solder pad of the speaker jack and the pin 1
pad of P5.  Also check continuity between the center rear pad of the
headphone jack and the rightmost pad - with the headphone plug removed,
there will be continuity there if the switch in the headphone jack is
operating.

Low audio in the K2:  The K2 does not have a lot of excess audio gain,
but one should not have to run the AF gain all the way up to hear - the
10 o'clock position should be more than enough for normal levels.  If
you have to run the audio above the 12 o'clock position, you may have a
different problem in the receiver.  How does the S-meter respond with a
50 uV signal from a signal generator like the XG1 or XG2?  It should be
about S-9.

73,
Don W3FPR


On 1/21/2011 9:42 PM, ve7ymm wrote:

> My new kpa100 looks like its working okay except for the top cover plate
> screw holes not being deep enough.  I guess I will just use some lock
> washers under the 3/16" screws. No QSOs yet but all seems to check out
> according to the specs. However, the headphone jack switch that allows the
> speaker to work quit after about 3 months of use, just like the one on my K1
> did. The speaker doesn't work, nor does the external speaker jack, just the
> headphone jack.  I put in a new one while I had the K2 apart for testing the
> kpa100, and now it still doesn't work.  Any suggestions on troubleshooting
> this?  I might add that the headphone volume seems low to me.  I normally
> have the af and rf gain on all the way.  Should I just give up, and use
> amplified speakers with the headphone jack?
> Mark Mellish, VE7YMM

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[ve7ymm]

Don,
Your help is, as always, clear, concise, and greatly appreciated.  I measured the depth of the screw holes carefully, and they are too short.  I will see if Elecraft will replace it.

I checked the headphone switch for continuity as you suggested.  It seemed okay.  I installed the K2 top, and the speaker now works.  I reinstalled the KPA100, and it too works.  I must have not had the speaker plug installed properly.  I think I will try using amplified speakers that have a separate headphone jack to save wear on the K2 one.

I will order a XG2 kit to test the receiver as you suggest.

Thanks, Mark Mellish