[R-390] Call for measurements - 100dB carrier reading

[Graham Baxter]

Hi Dave

Interesting stuff. I am still waiting to hear the verdict on R544.  I
think it controls the set-point for the AGC servo.

I can confirm that for the measurments I adjusted my IF gain for -7V
with 150uV into J513 set to MGC. This produced a somewhat higher
setting than I would normally use.

By "RF deck unplugged" I mean the RF multipole connector.

I think probably the most useful measurements I gave you were the open
loop AGC voltages.

I have repeated them with the downstream AGC line grounded

30uV  0.1v
100uV 0.2v
150uV -1.6 (This has changed, probably related to warm-up time).
300uV -14.4
1mV  -29.1



Grounding or floating the AGC line makes hardly any difference.

I did one final test which might tell us something. Loading the
open-loop agc source line with a 510k resistor pulled it down
(strictly speaking, up) from -28.8 to   -18.8 (10v). A 1 meg pulled it
down by  6v. A 2.0 meg by 3.2v. These measurements were taken with a
10Meg multimeter already loading the AGC source.

This time I won't put the covers back on until I hear from you!

Graham