[Elecraft] deaf receiver...

[Wallace, Andy]

> -----Original Message-----
> From: Nate Lewis [mailto:nlewis59@attbi.com]
>=20
> I've got a mostly-deaf K2 that seems to think that all signal=20
> or noise is S3 at best, on all bands, and puts out very quiet audio. =20

Hi, Nate. My K2 also had very low sensitivity. I checked many things
"by the book" and was still scratching my head. One thing which would
really be an improvement to the K2 documentation would be some=20
oscilloscope snapshots at important stages in the rx, with a known
signal injected at the antenna jack. The difficulty I found was
that using a signal generator in the troubleshooting section and
looking at the voltage levels using the Elecraft RF probe, I didn't
see much that was off the listed values.=20

Since I assembled my kit using a binocular microscope, I was pretty
sure it wasn't a workmanship issue. However, since the problem seemed
to be in the post mixer amp area, I resoldered Q22, RFC11 (on its=20
collector) and C161 (the IF coupling cap out of Q22). This seemed
to fix it. Unfortunately, I shotgunned all three at once so I don't
know which it was! All three had solder joints that looked perfect.

I wound up rewinding and reinstalling the RFC and replacing the cap
anyway, just in case.=20

My suspicion is that Q22 was not soldered well, and from talk on the
Reflector afterwards, my thought is that perhaps Elecraft has a=20
batch of those transistors which may have residue on the leads. I don't
have the message handy but I believe someone else saw that.=20
No way to verify though it may be worth Scott taking a look in the stock
and checking. Or they may have already been used up...=20

Anyway, I'd check that area. I'm cc'ing the list in case anyone else
has had trouble around Q22 and can speak up.

My K2, before the fix, took over 350 uV in the antenna jack at 7 MHz for =
an
S-9 reading. Now, it is 110 uV or less, and the other bands match=20
pretty well what the QST review quoted (see the Elecraft site=20
for the review).=20

Andy
=20