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RCA Radiodyne 28
#46

100 ma plate current? Something is not connected correctly?

However 480 ma "A" current would be right .060ma x 8 tubes at full 3.3 volts. Oh! Allow a few ma to energize the "new" meter...

V9 was an early production inclusion. It was eliminated as the model progressed and eliminated entirely from the AC version. If the power harness is correct, the three V9 leads are connected and taped off. Or it is a late edition harness without the leads for V9.

You must connect the harness to satisfy the radio as DC. because of the circuit exchanges in the jumper strip... Those changes must now see the TERMINAL strip as DC...

Might, be powering "B" to only the amp and not the RF/IF stages.

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
#47

What I’m seeing at the battery connection strip at 110 v. is 21 v. (Post 10), 35 v. (Post 11), 134 v. (Post 19). Posts 10 & 11 have caps 12 &15 in the circuit. Is that a mistake on my part?
#48

Rob,

The whisker wires exiting the Cat and connecting to the terminal strip do not exactly sequence the terminal strip. I ALSO suspect that the sequence of connections to the terminal strip is different for the AC vs the DC radios. Follow the DC schematic:

Note the jump in the whisker count...

   

The terminal connections for power must match the DC battery strip connections.

   

The DC battery strip MAY not be the same as the AC strip, possible a lug in an incorrect position. That may be the problem.

Trace every connection from what we think is the correct DC power strip to the whiskers including the count for the whisker connections. That is the likely place for the error.

All assumes the cat passed the continuity test after the transformer replacement AND that the new jumper strip is correct... It is possible a return to C+ may be incorrect at the jumper strip or a short at one of the lugs.

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
#49

SUCCESS! Using the DC schematic I found a misplaced whisker. The radio is in need of some more cleaning and tweaking but it is working well. Thanks Chas! Another patient brought back to life. - Rob
#50

Hurrah! Hurrah!

Good job Rob,

You are now a Catacomb expert...

I have mentioned this thread URL to Dave Slusarczyk  of ARF. He is an avid Radiola fan.

If you can post more images and text of the progress it would be helpful for anyone in the future to convert an AC Radiola Catacomb to DC for an ARBE-III...

Best!

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
#51

The radio is ready to go into the cabinet. I’m using the RADIOLA 100 speaker which was one that RCA recommended for the radio. Nice sound! - Rob     
#52

Nice work, Rob! Take care and BE HEALTHY! Gary

"Don't pity the dead, pity the living, above all, those living without love."
Professor Albus Dumbledore
Gary - Westland Michigan




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