Re: K2 VCO Alignment T5 L30
Posted by
Don Wilhelm on
Jan 20, 2019; 1:22pm
URL: http://elecraft.85.s1.nabble.com/K2-VCO-Alignment-T5-L30-tp7648249p7648335.html
Tom,
Good work on the VFO.
Before you replace U11, measure the resistance from the wire on the
carrier board to the lead of the SMD IC. Do that for all pins. The PC
traces on the carrier board are not thru-plated holes and sometimes
become damaged with soldering.
73,
Don W3FPR
On 1/19/2019 6:35 PM, K2bew wrote:
> Don et al,
>
> I tried a 15pf cap ( what I had on hand) at the source of Q19 to
> ground and I got .025v on R30 that did not change with the adjustment
> of L30, essentially no voltage.
> So, I took it off and it went back to 4.5 volts. So, then I tried
> Vicenç, EA3ADV's suggestion and I put 17 turns on the red wire of T5.
> That got me a voltage of 8.5V on R30 with L30 bottomed out that I
> was able to easily back off to a stable 6 volts.
> I went ahead and did the voltage tests on the other bands and had a
> nice range of 1.844 to 6 volts as my low and high on the VCO.
> So, that's all set.
>
> However, new problem. I went on to the test the BFO and I have 0000.04
> kHz. on TP2, so it's not working.
> I went to the trouble shooting guide and I have 0.058 Vrms on pin 6 of
> U11 with the RF probe.
> Looking at the archives of the reflector that would indicate that U11
> is bad and I need a replacement, correct? or are there other things I
> should look at first?
> The good thing is I'm becoming very accustomed to the radio and
> enjoying the trouble shooting.
> Thanks for all the help, I really appreciate it.
>
> 73,
> Tom Bewick, K2BEW
>
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