Free TV Sets Available at the Museum - Videokarma.org TV - Video

Steve McVoy · #1 07-12-2021, 02:56 PM

Free TV Sets Available at the Museum

We have many 40s and 50s TV sets that we need to get out of our warehouse. They are available at no charge, but you must pick them up during our normal hours. Here is a list of the sets.

https://earlytelevision.org/free_tv_sets.html

Yamamaya42 · #2 07-12-2021, 03:08 PM

such a shame you are so far away from here.

kf4rca · #3 07-18-2021, 09:25 AM

Available in the Atlanta area for free. If you're unfamiliar with these they have a 30 inch round metal CRT.
It is complete except for an HV transformer. BUT, this should be easy to cook up. Unlike conventional TV's this uses an autoformer (only 3 connections. The HV oscillator is not part of the horizontal circuit. I think even an old ignition coil from a car would work.
I inherited it with the transformer missing. I think it burned up. (typical.)
They are easy to transport in an Econoline van. Take out the top latch, put in the TV and re-install the top latch. I also remove the chasses to make it lighter, then re-install them at the destination.

WISCOJIM · #4 07-18-2021, 10:32 AM

Quote:

Originally Posted by kf4rca

Available in the Atlanta area for free.

How does the CRT test?

.

kf4rca · #5 07-19-2021, 05:55 AM

Good, the last time I checked it. Five years ago.
Its been stored inside its whole life. Cabinet is in fair shape.

Tom9589 · #6 07-19-2021, 09:15 AM

Not to burst your bubble, but I don't think an ignition coil would work. The resonant frequency is way too low. The Dumont transformer operates at 15,750 Hz. On an ignition coil on a V8 engine operating at 5,000 RPM, the operating frequency is only 333 Hz.

This transformer really is made out of unobtainium.

kf4rca · #7 07-19-2021, 10:14 AM

Thanks for the info.
Alternatively you could use a tube type color flyback to develop the HV. Probably have to experiment with this.
Pictures to follow.

Tom9589 · #8 07-19-2021, 11:45 AM

Now you are talking. Since the CRT only needs a maximum of around 1 mA @ 20KV, you might be able to buy a ready made power supply. The biggest problem I see is the varying current load due to picture content. Don't know how good their voltage regulation is.

Electronic M · #9 07-19-2021, 11:58 AM

If originality isn't a big concern you could use a flyback from a BPC, a power FET and a 555 timer and make your own HV supply. I built a plasma speaker (an HV arc that reproduces audible sound from a signal source) with such a setup. BPC flybacks also produce low voltage power supply feeds and those taps are affected by HV loading so if you used one of those taps as a feed back reference you could probably regulate the circuit that way (or just use a 6BK4 if that's easier for ya).

DavGoodlin · #10 07-20-2021, 11:00 AM

The idea of a 6BK4 in a monochrome DuMont is the ultimate feature for such a rare giant.

Give it a try once you're making HV, driving grid with an HV control and consider using a copier's HV power supply or another form of "tripler" circuit. 20kV is not hard to make this way.

Only in a DuMont would the Horiz sweep-only drive the yoke and provide the necessary blanking and keyed AGC

kf4rca · #11 07-20-2021, 01:57 PM

This sets original owner was WCSC. They also had a Dumont transmitter (before they went color). The Dumont transmitter was vapor phase (water cooled) as I recall. Vapor phase cooling is unusual for a VHF transmitter.
Anyway, when the HV coil went bad, they chose to just replace the set with a new rectangular set.

Dude111 · #12 07-21-2021, 12:38 AM

I wouldnt take one FREE,I dont like taking advantage like that..... I would give probably $100 if I had it to give......

Donsteleviso · #13 07-21-2021, 10:44 AM

Quote:

Originally Posted by kf4rca

Available in the Atlanta area for free. If you're unfamiliar with these they have a 30 inch round metal CRT.
It is complete except for an HV transformer. BUT, this should be easy to cook up. Unlike conventional TV's this uses an autoformer (only 3 connections. The HV oscillator is not part of the horizontal circuit. I think even an old ignition coil from a car would work.
I inherited it with the transformer missing. I think it burned up. (typical.)
They are easy to transport in an Econoline van. Take out the top latch, put in the TV and re-install the top latch. I also remove the chasses to make it lighter, then re-install them at the destination.

Do you still have the set?

Donsteleviso · #14 07-21-2021, 10:46 AM

Do you still have the set?
[email protected]

dieseljeep · #15 07-21-2021, 11:10 AM

Quote:

Originally Posted by kf4rca

Good, the last time I checked it. Five years ago.
Its been stored inside its whole life. Cabinet is in fair shape.

The last 30" model they made was built to use up the last of the cabinets and CRT's. It had a single chassis that looked like one used in a 21" model.
It was sold to John Folsum, the collector in Florida.
He thought it was a Frankenset, but I replied that it was original because of the tube location diagram matched the chassis.
Naturally, the CRT was a rebuilt and weak, with a britener.
He probably still has it to this day.