In article ,
"clive & kristi ingram" wrote:

hi. i've got a hallicrafters sx-42 that has developed a strange s meter
problem.the receiver works on all bands but the s meter works normaly only
on the first 2 bands,broadcast band and band 2 (1.6 to 5 mc). when I switch
to band 3 (5
to 15 mc) and bands 4, 5 and 6 i hear signals but the s meter indicates
zero. occasionally
there will be a very slight negative indication with the needle moving below
the zero. it
must be getting ok avc on the first 2 bands but not on the others. does
anyone have any
suggestions?

ci-

My understanding is that the S-Meter is measuring a negative voltage
(AGC) that is developed at the AM detector, and is used to limit the
amplification of an earlier stage.

For the meter to read down-scale, there could be either a vacuum tube
that is "soft" or a DC Blocking capacitor that is leaking. You may find
a tube that has positive voltage on its control grid. That could either
be caused by the tube or the capacitor that feeds it.

Fred
K4DII