[R-390] R390A RF deck advice

[Roy Morgan]

On Jan 10, 2015, at 2:25 AM, Roger Ruszkowski <flowertime01 at wmconnect.com> wrote:

> 
> Barry,
> 
> I put some other bad numbers in a post.
> The IF deck needs to get us 27 28 to 1 for 150 uv at 455.
> we will never see a receiver do those numbers end to end.
> We would like to see 20 : 1 end to end. 
> We can get a bit over 20: 1 but you need to really pick tubes to get much over 20:1 end to end for noise.

Roger,

Just checking that I understand the basics:

By:

> "The IF deck needs to get us 27 28 to 1 for 150 uv at 455."

You mean:
Put 150 microvolts into the IF deck input at 455 kc
Set the right bandwidth (4 kc?)
AGC off
Turn signal generator modulation on and off (30 percent at 1 kc) and look for 27 to 28 to 1 noise voltage level change at the audio output.

and by 
> "We would like to see 20 : 1 end to end. “

You mean 
Put the signal into the RF input of the radio
Signal modulated 30 percent 1 kc
20 to 1 modulation on to modulation off, audio tone to noise at the audio output.

I know you’ve described this noise test before (and I’ve saved it here somewhere) but I wanted to check the basic ideas.

I do have a URM-25F here, but unfortunately no R-390 of any sort to test.

Roy

Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958