http://elecraft.85.s1.nabble.com/Strange-receive-problem-tp389057p389061.html
sensitivity will be the obvious result. This is separate from a VCO lock
that is the only way to go. Remember that Murphy rules in instances like
> -----Original Message-----
>
> Thanks Don,
>
> I'll move the probe to TP1 and see if it changes when receiver
> sensitivity falls off.
>
> I thought that if VCO voltage was low PLL lock would be lost.
> When this happens, the PLL stays locked, as verified by listening
> to stronger stations. Also the VCO/PLL chain is before any RF
> amplification of a transmit signal. Hence my perplexing
> question. A single transmitted dash brings it back. (As I was
> typing it went quiet, and a single dash made things right.)
>
> To pose another hypothesis, when it goes insensitive (I can
> still copy very strong signals) it is almost as if the 20m
> components were being switched back in. There is no relay
> chatter, and I set sidetone level to zero, and AF to zero after
> it happens, and when I transmit no relay noise. Could the I/O
> controller be the problem? Sending a small voltage to the relay,
> but not enough to latch it back causing a high resistance
> connection at the wipers to partially enable the 20m components
> in the BPF. And transmitting a signal forces it closed?
>
> After I added the KX60V I went through and did the VCO voltage
> measurements and 30 was fine.
>
> You are correct that there are very few portions of the radio
> that are band specific, namely the VCO circuit which switches
> the diodes, the LPF and BPF, and the I/O controller which affects
> the first three.
>
> I'm feeling pretty stupid as I can't find the problem. I knew
> once I posted you would be kind enough to give me your
> experienced opinion. I am just suprised that as the Dean of
> Support you have not seen this before.
>
> Again thanks for taking time to consider my plight.
>
> Regards,
> Joe N9JR
>
> Don Wilhelm <
[hidden email]> wrote:
> Joe,
>
> Try checking the RF voltage out of the VCO (at TP1) - compare 30 meters to
> 40 and 20. If the 30 meter output is low, that could be the major cause of
> your problem. If this is the situation, look first at the voltage at R30
> for clues. Normally the 30 meter VCO alignment falls quite within range,
> but if the capacitors in the VFO selection area are not quite the right
> value, it could make any one band go out of range.
>
> Other than the BPF and the VFO range, there is not much that is band
> specific in the receiver - all it takes is things tuned to the correct
> frequencies.
>
> 73,
> Don W3FPR
>
> > -----Original Message-----
> >
> > I have been pulling my hair out for about a month with this
> > problem, and perhaps someone has seen it before and can point me
> > on the right path.
> >
> > I have an issue on 30m receive only. When I transmit on 30m I
> > get full power, and it receives normal, but after a while it
> > loses most of its sensitivity. Transmit again and it will hear
> > the other side of the earth. I have noticed that once it goes
> > partially deaf I can get a High Curr indication on the first dash
> > I send, but after that it puts out full power with no complaints
> > and of course after every transmission it is that beautiful K2 receive.
> >
>
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