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I want to build an AM Tube Tuner

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I'm looking at RCA receiving tube manual RC-17. Page 277, circuit 17-8. 3 tube AM receiver. 5Y3 rectifier, 6BA6 RF amp, 12AU7 detector & audio amp. 10 Rs, 15 Cs, 1 RF xformer, 1 power xformer, 1 loop antenna.

Looks easy...

RCA RC-xx must be online somewhere. That's where I would start. Hard part will be finding the variable Cs, and would guess layout is everything.

I personally would start with an existing tuner. You can get it working, then gut it for your scratch build. Fer'git Fleabay, and get one from one of the antique radio sites for $30. Don't tell 'em you will gut it.

Bad news, is that when you are done, you will get AM broadcasts. 'round here, it is Rush Limbaugh and Mexican.
 
AES has some simple kit stuff.

How complex do you want to get? A superhet circuit is not out of the question, but your test bench needs to be fairly sophisticated. OTOH, you could use the pentode section of a 7059 as a regenerative detector to feed the tube's triode section set up as a common cathode audio gain stage. While a regen circuit is not nearly as sensitive or selective as a superhet circuit, you don't have the alignment issue.

Dude, you're taking me back 50 years. :)
 
Struth Eli, we must be similar in age (my fullest sympathy).

I have used a detector of a diode directly coupled to a cathode follower for superior linearity (dual triode used - circuit can be posted). But as Eli said you must first say where you want to go as in how complex.

A regenerative circuit is fun but very narrow-band. A tuned rf gives purer sound - if stations are so situated that poor selectivity is not a problem. Otherwise a superhet, for which you will need at least a decent rf signal generator, apart from multimeter etc. What are the frequencies in your region, medium wave, long wave - or were you thinking of a more complex all-wave job? For the latter, unless you have experience or are VERY adventurous, a kit might be less prone to drive you to suicide, if still available.

Ah, yesteryear... In South Africa in the 50s there was available those extremely good-looking multi-band Geloso kits from Italy.....

Regards.
 
I just need 880 Mhz and 1050 Mhz.

I think you mean 880 KHz. and 1050 KHz. Mmmm, 880 KHz. is WCBS in NYC.

Only 2 stations, you say. A superhet might be in the cards even with limited test equipment. You could try to source 455 KHz. crystal filters. That would eliminate aligning IF trafos. Ceramic filters are a possibility too, but voltage followers would be needed to protect them from the B+ rail. You would need 2 sets of coils for the front end. An antenna coil for the freq. of interest and a local oscillator coil tuned 455 Khz. higher than the freq. of interest. Relatively large inductances and a small capacitance are indicated for the antenna "tanks", while a relatively large capacitance and small inductances are indicated for the local oscillator "tanks".

The 7059 would make a fine 1st detector and local oscillator. The Hartley circuit will do nicely for the local oscillator. 2 or 3 12AU6s would take care of IF amplification needs.
 
sbelyo said:
I don't want to get too crazy because I don't have all the test equipment.

What about a crystal set, then amplify the output?

Disadvantages: needs a good signal

Advantages: Sounds good, no drift, no test equipment, simple.

A good antenna will be the key. For good sensitivity and selectivity you could try a passive tuned loop antenna like this for example http://www.mindspring.com/~loop_antenna/
 
Here Is A Really nice looker, They have a schematic posted, though it may be more complicated than what your looking for.
http://www.indianaradios.com/Miller...0AM Tuner.htm
Circa 1942, PERFECT for Baseball games!!


I know someplace here I have a heathkit schematic & manual for a tuner, Lost in my jungle that once was a garage
:D

I have a 1946 GE model #221 I use to listen to The Chicago Cubs on almost daily. I turn off the ole surround sound, Crank the Ole GE up, And listen to the game the way baseball was meant to be heard. After about 20 minutes, The Video delay is not even an annoyance LOL

Mine is the lower right hand model in the advertisement.
An externally hosted image should be here but it was not working when we last tested it.
:D
Trout
 
My father once said that he had upgraded his first crystal radio to vacuum diode.
His surprise was that he could still hear clearly for several minutes AFTER heater
power was shut off to the cathode. Go figure...

I got no plans for a broadcast receiver, perhaps an all tube Theremin some day...
Though I've run into difficulty figuring the needed coils, and where to tap the
cathode into the grid coil to make an oscillator??? Drawings look like 1/4, but
is that the actual winding ratio?
 
info on building your own tuning capacitor.

I've seen antique radios somtimes had a variable inductor that
was constructed upon two air cores of slightly different size.
Such that one core could fit completely inside the other and
be rotated through 180 degrees without hitting. Thus each
coil could add or buck the other, depending upon orientation.

I might also mention that each coil form (cardboard tubes?)
was wound tightly at each end with a wider spaced turn in
the middle. The wider space to give access for a dowel or
other shaft to penetrate the outer coil and rotate the inner.
 
Crystal Radio Page

Check out HobbyDyneII for photo of variable inductor I tried to describe above.
Though most antiques I've seen are built one completely inside the other, I see
no reason Hobbydyne method wouldn't work. Sometimes close is close enough...

http://www.makearadio.com/misc-stuff/variometer.php

Yeah, now this appears much more like the inductor I was trying to describe.
 
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