I recently picked up one of these to help out with my radio restorations. I downloaded the manual from BAMA (http://bama.edebris.com/manuals/rca/wr50b/). It looks all original and very clean inside :)

http://farm6.static.flickr.com/5123/5220096506_ff61f1882c_z.jpg

http://farm5.static.flickr.com/4125/5219504905_29b92fd56e_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/5125/5220096928_d01e362576_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.

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/5164/5233289867_01b1edf9de_b.jpg

455 kHz IF response
http://farm6.static.flickr.com/5084/5233882978_7230323a3c_z.jpg

RF output
http://www.bobandersen.com/images/equipment/sine%20wave.jpg

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/equipment/WR50B@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.

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.

Congrats on the acquisition-it's funner to test/align old stuff with old stuff.
But...
Isn't that a rather non-linear sine-wave?

Actually, that's pretty darn good for an inexpensive, vintage tube based generator. Also, often they were designed to have harmonics for the high bands which distorts the sine wave a bit.

Yeah, the accuracy of the generators sine wave is really of little importance for doing visual sweep alignment. What your looking at is the detected pass band of the receiver, so you can about throw any noise at it, as long as the RF sweeping frequency can be synced to your scope.

I went ahead picked up a WR-50B, and running it through the paces. Putting up on the scope, I'm noticing that the output seems a little bit off. Or is this the low frequency distortion mentioned earlier?

For example, here is what I get when I do a simple sine wave:

http://videokarma.org/attachment.php?attachmentid=173381&d=1329682112

Notice how flat the lower cycle is compared to the top. Also, when I do sweep mode, the blanking period is definitely not flat:

http://videokarma.org/attachment.php?attachmentid=173380&d=1329682112

And when I plot them both with the second being the output of my homebrew Sencore SG-165 demod probe, I get the following -- note the spike at the beginning of the sweep... related to the above?

http://videokarma.org/attachment.php?attachmentid=173379&d=1329682112

I wondering then, if this is an issue of basic calibration or if I should re-cap it first and then try a calibration?

Edit: Both tubes test excellent on my emissions tester. I've also found that different frequencies and different ranges have different levels of distortion, so wondering if it might be a calibration issue then. Also, I've found that if I turn the ON/OFF MOD past about 12:00, the modulation frequency goes down... hmm.

Those waveforms look pretty good to me. This is a fairly simple design and some distortion is to be expected. The original brown caps I believe are fairly reliable so didn't bother to recap.