Drake R-4b receiver sensitivity question.
 

I was aligning a Drake R-4B receiver. When aligning the receiver
sensitivity and the S meter the manual states to set the RF gain to
read -15 vols from TP2 (test point 2). The manual states to set the
meter to S40. At -15 volts the highest I can get my meter to go is
S20. I replaced every tube in the receiver except the first RF amp,
and the only reason I did not replace that tube is because I don't
have one of those tubes at this time.
The alignment instructions for this section are on-line at;

http://www.wb4hfn.com/DrakeManuals/R...ual_R4B_38.jpg

The full Drake R-4b manual with schematic is on-line at;

http://www.wb4hfn.com/DrakeManuals/R4B/Manual_R4B.htm

Any ideas why the S meter will not go to S40?

Have you tried making a comparison with another radio side by side to
check for sensitivity without looking at the S meter?

Gil

As vaguely recall the test point requires a very high impedance meter. I
think the 11 megohm vtvm is what is normall used. Unless the meter used is
high enough, it will load down the circuit and when removed, the negtive
voltage will go higher thus reducing sensitivity.

But, I think it has been 10 years since I played with the R4B.

73, Colin K7FM