Collins S51S-1 Question.

[Kurt Brandstetter]

Hello to all!

I have some problems with my Collins 51S-1:

The rig is working 1st class on AM and LSB; on CW and USM the NF output
is quite low; especially NF signals arround 900 Hz is sometimes nearly
not audible. NF signals arround 400 and 2000 Hz are better, but also
much lower than on LSB.

I've tried it with AM signals on LSB or USB, and with a signal
generator. (Unfortunatly I don't know how to work with the sweeping
unit).

The RF indication on the meter (RF Input) is the same on USB and LSB,
sometimes about 10 to 15 dB lower on USB.

On AM there is a very small heterodyne, when I tune to a boradcast
station and tune away about 500 Hz from the center frequency.

Rejection tuning works ok.

When the receiver warms up over 1 hour, I feel, that the USB signal
becomes a little bit better, but also sometimes disorted, especially at
high signal levels.

Sometime ago (the problem became mor the last time) I measured the gain
control voltage. On USB it was higher than on LSB at the same RF input
from the signal generator. The voltage was about 3 V with a strong RF
signal (indication on S-meter 40 - 60 dB).

T7 I have adjusted (with crystal calibrator on) to the highest
indication on the S-meter; I think, then there is the gain regulating
voltage high.

Last not least, since a week, the 10+ and 0 dBm indication on the meter
does'nt work.

Because I don't know very much about retuning such a unit, I'll be
careful and ask before I make some mistake. Can someone of you help me
and give me an advice, where and how I should begin to look for the
problem.

I have a signal genarator (I think a good one, but there is no label on
it, I think it was used sometimes in Hungary, but has US valves and
script on the front panel. I have no manual for it)

Also I have a small oscilloscope and a digital voltage/resistor meter
and a capacitor measure bridge (hope you understand my English).

Greetings for now, hoping for some good help.

Kurt. OE1002419

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end

73's de OE 1002419
Kurt from Vienna Austria
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