TheRadioBoard

I'm fortunate enough to have a pre WWII RCA tube manual. In the back there is a schematic for a 4 tube AC operated regenerative receiver with plug-in coils. I have some octal sockets and a few nice variable capacitors. Has anyone built this classic? Is it worth the trouble? I was told in the middle fifties by my next door neighbor's dad who was a US Navy radio tech in WWII that it worked well if you had the patience to build it. I would have to find plug-in coil forms on ebay and buy an aluminum chassis. I would like to see layouts that other builders have used for this receiver. I'm old enough to remember that heater wires are black, and you should twist them together and dress them against the chassis. Bill Young WD5HOH

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WD5HOH

I havent built a 4 tube but would love to see the schematic. I am into regens in a big way. Just posted a sound bite of my favourite one in the shack running last night on Youtube.(regen set sound)
Don VE3LYX

Bill,

Can you scan the schematic? If you email the scan to me I can post it on my website so we can have a look. Contact me via PM and I'll give you an email address.

Some thoughts. If you skipped using plug-in coils at first, and built it for one frequency range, say the AM broadcast band, you could try it out and see how you like its operation. If there are hamfests nearby you might find a scrap chassis you could use to breadboard it. Other parts, too.

I don't want to cannibalize Dave's forum, but the Yahoo regenrx group has some experience regen builders who never visit here, and one of them may know about it. I'm sure they'd be interested.

My assumption is that this receiver has an rf stage, detector, and two stages of audio. Sounds pretty good to me.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

Yes, it has two 6SK7's, one 6C5 and one 6F6 driving a speaker(?). The regenerative detector is a Meissner or electron coupled circuit with the cathode tapped part way up the tuned grid coil to provide positive feedback. Regeneration control is by screen grid voltage variation. If I were going to build this radio I would want metal jacket tubes. I also anticipate problems finding the 300 to 500 Henry audio choke and the necessary power transformer and the two audio transformers. Now that Fair Radio apparently is no more these items are harder to find, and anyway the varnish on old magnet wire can be unreliable.

Unfortunately I don't have a scanner, but if you'll be patient I may be able to redraw it. It's not that bad. Bill Young WD5HOH

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WD5HOH

Some of the older RCA Receiving Tube handbooks are available online; I had a few until the *&^$#! backup HD failed... Does yours have an RC-?? number? Or a printing year? Might be able to get it that way and save you the trouble.

EDIT: Here's where older RCA handbooks and other good stuff are located: http://www.tubebooks.org/tube_data.htm I'm pretty sure the latest pre-WW2 one he has is too early to use the tubes you mentioned.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

Here ya' go. . .Included two, sets that are favorites. . .



Enjoy!

Mike

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I like the K-I-S-S Principle: "Keep It Sane & Simple"
http://www.peeblesoriginals.com

My oldest RCA Receiving Tube Manual(I have 3) is missing all pages before page 7 including front and back covers, so I don't know the year of publication. Maybe it's not pre WWII. I'm sure it's earlier than 1960, because I have the 1960 handbook, and the 4 tube regen isn't in that one. I also have the 1975 handbook - the last one, I think. Thanks for the info about RCA handbooks online. I'll send this message and go look at those. Bill Young WD5HOH

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WD5HOH

Thanks. That's it. What year was it published? Bill Young WD5HOH

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WD5HOH

Both of those show up in my RC-14 manual. It is copyrighted 1940.

In the schematics, the numbers to the upper-left, start with "14".

This indicates that it is book #RC-14, 1940.

Those diagrams of those times, were in several books, for several
years. That three-tuber at te top, shows up in many RCA tube
books of that era. I have the original Popular Science article,
that the set originally appeared in.

That 4-tuber, looks like it would make a nice set.

Enjoy!

Mike

_________________
I like the K-I-S-S Principle: "Keep It Sane & Simple"
http://www.peeblesoriginals.com

Mike, do you think the tuned rf amplifier stage is excessive? I can't see a dc return on the rf amp's control grid, and its cathode seems to have a fairly high positive bias, so I guess its gain is low.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

Well, I guess I would build it first, play with it and test it, then decide
whether it needed tweeking, or not.

That's why all this is so fun. . .EXPERIMENTING!

That's how I'd make those type of conclusions on how a predesigned set might work. Unless, of course,
if there was a very obvious mistake, that sticks out like a sore thumb.

Also, my experience with regen sets is that, usually a broadband, untuned RF amp is quite adequate.
This pertains to AM/BC, and may be different for SW + a person's locality, and ant/gnd situations are different.

This all brings us back to: EXPERIMENTING!

Whomever builds this set. . .please keep us posted on what your experiences are, with it. . .Have fun!

Mike

_________________
I like the K-I-S-S Principle: "Keep It Sane & Simple"
http://www.peeblesoriginals.com

Yeah, RCA wanted to sell tubes, after all. One interesting mod would be to make the rf amp stage regenerative. That would make for nicer skirt selectivity on the BCB. One of these days I may try that. But not with tubes.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

The diagrams in my manual all have"15" on them. The 4 tube regen is 15-8. So my manual is the next one after 1940. Would that be 1941 or did they wait until 1945 to publish a new one? Bill Young WD5HOH

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WD5HOH

According to the link below, RC-15 was published in 1948.

http://www.pmillett.com/tube_data.htm

Looks as though you can download that edition here, too:

http://www.tubebooks.org/tubedata/RC15.pdf

73,

_________________

http://kr1s.kearman.com/
http://qrp.kearman.com/