[RadioSvit]

Hello everybody . I recently bought a great RCA Radiola 26 radio, but as it turned out I had to replace three UV199 tubes. Where can I buy them and can someone sell them to me? I will be grateful for any information.

   

[RadioSvit]

Yes, Michael. I was wrong and already corrected.

[Phlogiston]

UV 199 tubes are not the greatest, even when new. The cathode looses emissions easily, by too high or too low of filament voltage. They often "go to sleep". The GM on them only needs to be around 240 but that is difficult to obtain on many of them. The UV version can be rejuvenated by running the filament at about 5V overnight. Then reset to 3.3V and run them for several hours prior to testing. Most of the filaments will stand up to this and I have had about 50% success in making them usable.

Some of these tubes seem to loose emissions in storage. Makes me wonder about the quality of the vacuum. For the record: UV pin-out IS NOT THE SAME AS UX tubes. If tested as a UX, plate voltage will be applied to the filament - BOOM. You probably know all of this but I thought that I would make sure.

E-Pay listing:

https://www.ebay.com/itm/LOT-OF-7-UV-199...SwRFxgC5iz

But I would not buy them for that price. There are usually more of them listed but not today. A known good one is worth about 20 - 25$. There are brass-base ones also but these are around 50$.I would not use them very often - or at all.

In general a pretty flakey tube. But the UXs are better. You could build an adaptor and use the UXs. They can be as little as $10 ea.

Those subs I showed you guys on my blog using a 3V4 would work well in the front end or as an audio amp (last tube) but might be a little squirrely if used in that radio's IF.

Russ

Do you know if the "catacomb" is in good shape? It is a melt-out and repair job that can be a little difficult.

[Chas]

RadioSvit,

Has a continuity test been done on the catacomb and did it pass?

Are you missing the cover for the tubes?

Has the sound reproducer been tested for music reproduction?

Often the cover jams on the reproducer, the cover is part of the diaphragm spacing adjustment, the internal gaskets harden, making the reproducer sound awful...

If you are in the Ukraine, do NOT let your eBay seller of tubes ship tubes by eBay Global Shipping. To eBays shipping partner contractor all tubes contain mercury because they are silver and are confiscated. Money is returned but no tubes...

Hint, avoid Song-Bird brand, very fragile both the glass envelope and the filament. The Silvertone brand with the box plate and the hair-pin filament are the most rugged.

The catacomb is built without internal shielding, it will not work properly with substitute tubes...

Try:  http://www.findatube.com/

Site states foreign orders are welcome...

You will find this article useful: http://www.nostalgiaair.org/References/A...lash08.htm

One of the charts has a filament voltage error, too low...

Chas

[mikethedruid]

If worst comes to worst you might make substitutes for the 199 tubes. They are a basic triode, fairly similar to the 01A. Here is a link to an article which might be of interest to you...  http://www.greenhillsgf.com/Project_SS-Tubes.htm

[Arran]

It may also be a good idea to try resoldering the pins of the UV199 tubes you have, failed solder joints is a common problem with 201A, and even AC tubes like #24As. I have also heard of people using 3Q5s and 3C5s as substitutes for 199s, with an adapter, since the envelope looks similar at the top end.
Regards
Arran

[Chas]

In radios that have fewer tubes and a combination of separate filament rheostats substitutes for '99's will work successfully as the gain can be reduced for each stage. The Catacomb controls the filament voltage of but one of the tubes as a volume control the other tubes operate at the 3.3 volts, 0.060ma each with a bias of 4-1/2 and 9 volts. A further restriction is interconnecting wiring is confined to inside the catacomb. Unless there are other internal issues in the catacomb requiring a melt out, changes to the circuitry internally are not possible.

[RadioSvit]

I am sincerely grateful to all of you, friends, for your interest in this problem and my desire to help. Thank you, I am pleasantly surprised by such activity.
Regarding radio lamps. Yes, three radio lamps are working, the lamp tester shows about 10 mA. In the fourth the filament disappears, there is no resistance. Maybe it's just a defect in the base. But in two radio lamps the resistance of the filaments does not show any resistance. So I have to replace at least two ... three radio lamps. Therefore, I am set to put three serviceable radio lamps in the high-frequency part (VF and IF), in the dlector and amplifier may have to put replacements, if I do not buy the original lamps.
  I looked with great interest, perhaps all the materials on this radio on the Internet and could already consider myself a guru to repair the radio brand Radiola  , but of course this is not the case, I'm just learning.   Therefore, I am sincerely grateful to you once again for very interesting information. I learned that you can use some battery pentodes in triode inclusion, such as 3V4 and which have a Soviet analogue 2P1P. So I have already received a backup option to solve the problem of radio lamps. Thanks again to Rass, mikethedruid, Arran. However, of course I will try to buy original radio lamps.

About the catacomb. It does not seem to have opened yet and is intact. This made me very happy, but ... I found that there is no anode voltage at the anode of the first radio lamp - so there is probably a break in one of the circuits in the circuit and the catacomb I have to disassemble. However, it is now minus 15 degrees below zero and I will leave this pleasure for warmer weather. So I'm very grateful for the information on its repair, thank you Chas

I had another problem. As you can see, I bought a radio without a front door with a frame rotary antenna. I have to make it myself, but I did not find information about the number of turns and the diameter of the wire of the loop antenna. Have any of you seen such information and can you tell me where to look for it.

There is also no cover for radio lamps, so I would be happy to buy it too.
But now I went to study the information you sent me in the links. Thank you again. Peter

[Chas]

Download this manual for the Radiola 26 catacomb, find info on pdf page 270:

https://worldradiohistory.com/ARCHIVE-RC...3-1928.pdf

The Gernsback manual has a common sense re-draw of the Catacomb and all of the circuit quirks possible at the time:

https://worldradiohistory.com/BOOKSHELF-...-Vol-1.pdf See Gernsback index page 249...

If the plate circuit to an audio amp stage is open or a grid circuit it may be a defective audio transformer.

The is an effective and relatively safe method to melt out the potting compound. The potting compound is spruce rosin blend with bees wax. Once melted out do not return the compound as its melt point will have risen from out gassing of the bees wax... Not only will the compound melt at a higher temperature, it will shrink a great deal more and break internal wires... Chas

[RadioSvit]

Thank you very much,Chas .

[Phlogiston]

Here is a Radiola 25 with the wax removed:

   

   

[RadioSvit]

Oops ... I have a lot of work to do ... Thank you Russell.