Here is a link to a three pin fixed 9 V regulator. You only need to add two capacitors to it. Part of the 78L series. The TO-92 package (transistor size) can provide 100 ma.
http://www.digikey.com/product-detai...1-1-ND/5253742

Phil, thanks for the voltage readings. Its good documentation for the future.
However I'm not sure everything adds up. You are using 10K, 4.7K, 820 and 3.3K resistors and a 9 V supply?

I think I know why your voltage readings didn't make sense to me. First I made a math mistake, but also I thought you built old_coot88's version and I guess you built vts1134's. In that version the collector voltage varies as you adjust the pot to change the AC gain. I think if you check, the pot was adjusted to about 1.6K. That would mean the AC gain is about 2 instead of about 4 with the pot at 3.3K. Anyway you can't argue with success! :thmbsp:
More on that regulator; you can see the relevant data by clicking on the link on that page. The pages for the 9V version is on pages 4 and 9. You need at least a 0.33 uf on the input and at least 0.1 uf on the output. The regulator should be fed by at least 12 V.

Yes, I built what vts1134 posted, with a couple of changes. I used a 5K pot rather than 3.3K, because that's what I had on hand. I also changed the output capacitor from .002 mfd to .2 mfd, and changed R23 on the TV chassis from 5.6K to 56K. Here's a sketch of what I built, with some labels

http://antiqueradio.org/art/DuMontRA...eoPreamp09.jpg

The preamp/inverter seems to work well using either a 9V or 12V battery.

As for powering it from the TV chassis rather than a battery, old_coot88 suggested:

I tacked this together using parts on hand:

http://antiqueradio.org/art/DuMontRA...eoPreamp08.jpg

Using only one filter cap produced a faint moving hum bar, so I added a second. The preamp/inverter seems to work at this lower supply voltage (around 7.5V DC), although so far I haven't looked at anything except test patterns.

This is an interesting experiment, but I don't know whether I'll install this preamp/inverter. Yes, injecting the video produces a somewhat better picture, but the improvement is incremental, not night-and-day. In its current condition, the TV makes a watchable (although not perfect) picture without injection, as seen in this photo and video clip that I took a while back.

http://antiqueradio.org/art/DuMontRA...InputStill.jpg

http://antiqueradio.org/art/DuMontRA...inaryInput.mp4

(The horizontal bands in the video are camera artifacts.)

I've been slogging along with this project for a VERY long time. It would be nice to get this whale off my workbench and putter with something else for a change. Maybe I'll put the TV in its cabinet and try watching for a while. If I can't live with it, I can always install the A/V patch later.

Thanks,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

https://www.youtube.com/watch?v=1c96vgKZ1CM

:smoke:

Ha-ha! I've been discovered! Yes, that's where I got it from.

"No. No Time To Loooose!"
:smoke:

After a few more tweaks, I declared victory on the electronic front and put the RA-102 into its cabinet. I posted an article about the restoration here:

http://antiqueradio.org/DuMontRA-102...Television.htm

I'll refinish the cabinet when the weather improves.

Thanks to everyone for the generous advice, in this thread and others. Now I can launch the next project -- an Emerson 609 projection TV!

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

http://antiqueradio.org/art/DuMontRA...nCabinet01.jpg

http://antiqueradio.org/art/DuMontRA...Emerson609.jpg

Nice!

Phil, another great write-up!
:banana:

Very nice.

Outstanding job :thmbsp: I'd been wondering where that 3rd Buk Clifton ended up. Couldn't be in better hands :)

Great job!

It looks like the cabinet could use some touch up yet.

Yes, I haven't touched the cabinet yet, apart from brushing off the dust.

That reminds me, I'll need a Dumont logo decal. It looks like ETF no longer sells them. A guy on ARF has some spare RA-103 decals, but the logo in that set has jagged edges.

The RA-102 and RA-103 logos aren't identical, anyway. The RA-102 logo is 1/8 inch wider than the RA-103 and the letters are thicker. The RA-113 logo is wider still.

The RA-102 control decals are on the knobs, not the cabinet, so none of the RA-103 control decals would work, either. The RA-103 letters are too big and the curvature is wrong.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Phil, your tenacity and perseverance on summa these restos never ceases to amaze.

:tresbon:

My Clifton still has it's original finish and "Dumont" decal. I can take some photos and measurements.

The finish and decals on my knobs was quite deteriorated. I've stripped them in preparation for refinishing but not sure what to do about the tiny decals.

Here's a closeup photo of the logo I took back when I got mine. You can faintly make out some letters on the right knob.

Are the controls knobs in any better condition on yours ?

https://c1.staticflickr.com/4/3841/1...7a443a7629.jpg

The Dumont logo on my RA-102 looks like the RA-113 logo, only slightly smaller. Here's the RA-102:

http://antiqueradio.org/art/DuMontRA-102Decal.jpg

The RA-113 is about 5/16" wider:

http://antiqueradio.org/art/DuMontRA-113Decal.jpg

Perhaps a decal maker could reduce the RA-113 image to make one the right size for the RA-102.

I originally thought the knob legends were tiny decals, but now I see that the letters are recessed. I think they stamped the legends into the knobs and then filled them with gold paint. The legends on this knob say TONE and ON-OFF:

http://antiqueradio.org/art/DuMontRA...KnobDetail.jpg

If your knobs are stripped and the stampings aren't completely worn off, perhaps you could brush gold paint into the recesses and then wipe off the excess. That might work on some of my knobs, but on a couple of them, the letter recesses look worn away. A person with a steady hand and a tiny brush could touch those up freehand, but I suspect my fine motor skills aren't up to that task.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

I notice your set has six knobs wile mine has five. I believe mine is the earlier version which could account for the logos being a bit different - mine has an outline.

Most of the recessed letter has worn off my knobs. I think for the time being I'll just leave them be.

Yes, the earlier version (RA-102-B1) doesn't have the focus control in front. The later version (RA-102-B2) has an additional 30-ohm/10W resistor on that control. Riders lists three other small changes on page 1-43.

Phil Nelson