Quote:
Originally Posted by ablethevoice
As a few of you might be aware, I acquired my first (in a very long time) "real" communication receiver from the E place. It arrived slightly dented, but perfectly functioning. I'm having a lot of fun with the old man - actually, I'm 2 years older than it is so it's not that old  ...
Anyway, I've noticed a slightly odd behavior with the S meter: it reads signal strength and varies as the signal waxes and wanes in strength, but when there is no signal at all, the meter "pegs" at the low end of the scale. I've already precisely followed the procedure for zero-adjusting the meter as per the owner's manual, yet the meter still drops below zero in the absence of a signal - and only when the unit is ON. I would consider the possibility that I had overcompensated with the adjustment screw if the meter did that while the unit was OFF, but while unpowered, the meter reads at precisely zero. What might be happening in the guts of my old 145X to pull the meter below zero? |
Are you sure you followed the complete instructions in the manual? I have a Hammarlund HQ-160 which behaved the same way until I aligned it and zeroed the S-Meter.
There is a complete manual for the 145X at bama if you don't have one.
After mechanically zeroing the meter with the set off you short the antenna input terminal to the ground terminal. Turn the set on and let it warm up for at least 15 minutes.
Then adjust R24 until the meter reads zero.
The receiver will still exhibit the negative reading the in the future until it warms up fully. But once it does, it shouldn't read negative.
It is sensitive to the aging of V4 and V5, the 6BA6's, because it basically measures the difference in cathode currents of the two stages. If that IF stage is misaligned you can get even weirder results.
John