Dumont RA-108 ETF2009 Auction Score

[jshorva65]

Scored this Dumont RA-108 at the Auction during the 2009 ETF Convention, and just got its Restoration completed. Special thanks to Big Dave for hauling the set back to Warren with his truck and for installing the second Vertical Blocking Oscillator transformer after the first one I bought turned out to be a dud right out of the box. After all the hassles with the first one, I decided it would be best to make a team effort of it so we could double-check and triple-check everything to avoid any ugly surprises. I followed my usual procedure of thoroughly checking the electrolytics, leaving the good ones in place, and replacing only failing electrolytics and the unreliable paper capacitors. A full 80% of the electrolytics passed Leakage, ESR, and Tolerance tests with flying colors. If the still-good originals last another 5 years, I'll be pleased although not at all surprised. With the B+ line fused, I fully expect to know by some non-catastrophic warning signs (blown fuse, sudden appearance of a hum bar, etc.) in the event that one of them does fail. Besides that, I do regular maintenance check-ups on my sets and that has been a big part of the reason I've only had one "good as found" electrolytic fail on me since 2002. The 19AP4 in this set checked excellent, and the over-the-air picture from WJW (Cleveland, about 50 miles away) looks about as clear as on my '90 Magnavox "last of the Made-In-USA" set.

The RA-108 features an unusual "Dot Pointer" on its "Spiral" tuning dial. The main dial is illuminated by two #47 pilot lamps aimed downward and inward from above. As the Main Tuning and/or Fine Tuning knob rotates the main dial through several revolutions in going from Channel 2 through the FM and Aircraft bands all the way up to Channel 13, a rack-and-pinion arrangement moves a third #47 lamp along a linear path vertically. Since the third "pointer" lamp is enclosed in a sleeve with a single aperture, a bright "dot" is produced to point to a selected frequency or channel number marking on the main dial.

[spartanmanor]

Beautiful set!

[zenithfan1]

Very nice!

[sampson159]

that was a really great score! glad you got it together.looks very good.

[jshorva65]

Thanks to all of the posters of congratulations!

Pre-Emerson Dumonts have always seemed to be exceptionally well designed with reasonably roomy under-chassis layouts, so this set was reasonably easy to get going except for that issue with the bad NOS oscillator transformer. I ended up re-stuffing the two 80uF/350V main B+ filters and replacing most of the axial electrolyticslytics. Five of the six twist-lock cans tested as OK, but I re-stuffed BOTH of the 80uF/350V units since the two of them are wired in series to form a 40uF net capacitance at a higher working voltage. Both were reasonably easy to reach, so it made sense to re-stuff both while I was at it. All sections of the remaining "cans" re-formed to reasonable leakage values at test voltages 20% above rated VDC. With acceptable leakage at a "surge" test voltage equal to 120% of rated working voltage and ESR under 0.5 ohm, that's a "comfort zone" for me. The main reason for replacing some of the axial electrolytics that I replaced was due to their being strapped to the chassis and needing to be removed to replace paper/wax units "hiding" behind them, anyway.

[Tony V]

I have a Dumont RA-110 that looks similar and in a blond cabinet. I just completed the electronics but still trying to locate a usable 19AP4 Seeing yours playing gives me hope.
-Tony