RCA WR-50B AM/FM Signal Generator
 

I recently picked up one of these to help out with my radio restorations. I downloaded the manual from BAMA. It looks all original and very clean inside :)

http://farm6.static.flickr.com/5123/...61f1882c_z.jpg

http://farm5.static.flickr.com/4125/...b92fd56e_b.jpg

I'll replace the five paper caps and two electrolytics. I suppose I should replace the early silicon rectifiers too.
I figure a 1N4007 for the 1N3756 AC power rectifier. I'm not sure about the 1N3754 clamp diode though. Another 1N4007 ?

Then there's the varactor diode. I think it's this little device in the middle. No part# is given so I'll keep my fingers crossed that it's OK.
http://farm6.static.flickr.com/5125/...1e362576_z.jpg

All the resistors are within spec and the old caps seem OK too. So instead of recapping I slowly powered it up slowly on a variac to allow the electrolytics to reform.
It seems to work just fine :) It's still fairly well calibrated too.

I guess it's not quite as old as I originally thought. Maybe late 60s ?

According to the code dates on the pots, it shows mid 1973. Still fairly new.

Thanks. I hadn't noticed those codes.

I used it this evening to align my GE 212 radio. The sweep function works great and it produces rather clean sine waves.
http://farm6.static.flickr.com/5164/...b1edf9de_b.jpg

455 kHz IF response
http://farm6.static.flickr.com/5084/...30323a3c_z.jpg

RF output
http://www.bobandersen.com/images/eq...ine%20wave.jpg

Degrading output
 

Hi:

This is Tom M. from Washington state. Hint: I recently sent you my pictures of the Philco 46-1213, where I did the chassis recap using beeswax.

I recently acquired this same generator. I noticed on my scope a degenerating rf output to the point where it is zeroed out in the upper part of band D and on upwards. I did swap the 2 identical 12AT7's and still shows the same degrading effects of rf. I tested the tubes in my tester also. Both good.

Did you ever have this same symptom as well?

I haven't replaced anything yet. I will do all the paper caps & the 2 electrolytics. I am going to replace the 1n3756 with a 1n4007.

Out of curiosity. Did you end up replacing the clamp diode 1n3754? If you did, did you use a 1n4007? I am not going to touch that one until I know for sure.

One last thing. Did you ever find out what part# the varactor was?

Thanks, and keep up the great restoration work that you do!
Tom M.

Hi Tom,

I only replaced the 1N3756 with a 1N4007. The other diodes are still the originals. I don't recall using it on the higher bands. I'll fire it up and check later today.

Sorry, I don't know what varactor was used.

My generator works fine on the D, E and F bands. Here it is on the E band putting out 10MHz.

Good luck fixing yours.

http://www.bobandersen.com/images/eq...R50B@10MHZ.jpg

Yours looks great, mine looks like this, even running low freq in Band A.

Please let me know if you want me to keep you updated on the repair of this.

Thanks again for your feedback,

Tom M.

Sure - it might help someone else with similar problems.
Let me know if you'd like me to check anything in mine like voltage or resistance.

Delete the spammer!!!!!!

I don't get. Who's spamming? Me?

I'm all new to this and just looking for technical advice.

I looked up spammer and it said "someone sending repeated e-mail."

I don't think it is me, but I'm all new to this forum activity and I surely don't want to offend anyone!

I'm retired and far to old and weary to be doing any type of activity like this...

If it is me though, I'll step down and not respond anymore if you would like.

Sorry,
Sincerely,
Tom M.

Don't worry Tom, he's not referring to you. Late last night a spammer left a few random spam posts last night including one in this thread. It's been deleted which makes the comment above look odd.

Thanks for the clarification.
Now it makes sense!

Tom M.

I have more of a general question about the WR-50B. Can it be used to sweep align "non-standard" IF frequencies such as 465KHz, 470KHz, or maybe 8.3MHz FM?

Yes. Choose the sweep mode and center frequency. As I recall, it does a pretty small sweep width.