[Elecraft] K1 issue on 20M (not crystal related)

[Don Wilhelm]

Don,

Are you certain you have the Pre-mixer capacitors set properly for 15 
meters?  It is quite possible to set them for a response in the 31 MHz 
range instead of the correct 25 MHz range.  If that happens, you will 
not be able to align the Pre-mix bandpass to 20 meters.  Start with the 
15 meter capacitors set near the center position (with the slot pointing 
to the narrow end of the capacitor) and do not vary them more than 30 
degrees from that position while tuning.

Be certain you are really hearing signals in the 15 meter band when 
doing the initial receive alignment of the pre-mixer bandpass filter.  
If you do not have a signal generator for 15 meters, use another ham 
transmitter transmitting at low power into a dummy load and connect a 
short antenna wire to the K1 - place the wire near the dummy load.

After aligning 15 meters, try aligning 20 meters again.

73,
Don W3FPR

Don Herring wrote:
> Greetings
>
> I'm a newbie building a K1-4.  Everything was going OK until the 
> receiver alignment phase of the build where I ran into a problem where I 
> could not hear anything on 20M.
>
> After searching the list and several exchanges with Elecraft support, I 
> had not gotten anywhere in resolving the problem.   Based on previous 
> issues seen on the list regarding 20M, Elecraft did send me a couple of 
> replacement crystals for the band.
>
> In the mean time, I completed the transmitter section and was able to 
> get output on 40, 30, and 15 - no output on 20 as per an external 
> wattmeter.
>  
> Replacing the 20M crystal had no effect.  Using my Ten-Tec RX-320D, I 
> was able to verify operation of all the crystals, including 20M.
>
> I put together a RF probe this weekend and started signal tracing.  This 
> is what I have found, though the finding does not make much sense to my 
> inexperienced mind.
>
> At step 8 in the signal tracing procedure in the K1 Manual, I was 
> getting 0 voltage on 20M, and anywhere from 0.025 t0 .035 on the other 
> bands. 
>
> I started tracing back from P1 pin 6, and took a reading at T2 which is 
> the source of my puzzlement.
>
> I can see voltage on all bands going into T2 on lead 3, but no voltage 
> at lead 2 for 20M - I'm getting a reading on lead 2 for all other bands.
>
> So it appears T2 may be the source of my problem.  But it doesn't click 
> with me that the toroid can be a problem with just one band.
>
> One other oddity is that even though I'm not seeing any signal on the 
> external wattmeter I can hear 20M on the RX-320.
>
> Am I on the right track here, or do I need further testing before 
> working on T2?
>
> THX, and 73
>
> Don, KJ4MRB
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