RCA tube AM radio

egellings said:
Can't tell from the picture, but does it have a 3-gang tuning, um, condenser? The extra gang would tune the front end RF amplifier.
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Schematic is linked in post #7. I don't see that there is tuning for the RF amp. It's interesting though the way they added a phono input for just the cost of a switch.
 
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C1 should be the RF amp tuning section.

The switch setup was the common way of doing things. Its also a way to hack in an input for something that doesn't have one.
 
gadget73 said:
C1 should be the RF amp tuning section.

The switch setup was the common way of doing things. Its also a way to hack in an input for something that doesn't have one.
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Thanks, I see in the parts list that C1 to C6 are all part of the tuning capacitor. As to the phono input, why didn't every AA5/AA6 have one?
 
Some disconnect there between "dangerous as hell" and "feature of the more expensive set" but I can see how there could be problems with it.
 
Isolation from the power line is entirely by one capacitor. If that cap shorts your turntable is wired right to the power line. Less than ideal, but not uncommon for the era
 
audiotemp said:
Some disconnect there between "dangerous as hell" and "feature of the more expensive set" but I can see how there could be problems with it.
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They were also more common on older sets. I don't think any of the 1960s AA5s still had a phono input. The last tube radios had a safety interlock cord and prevented the user from ever touching anything metal.

gadget73 said:
Isolation from the power line is entirely by one capacitor. If that cap shorts your turntable is wired right to the power line. Less than ideal, but not uncommon for the era
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And to make matters worse, in order to keep leakage current low enough to be "safe", the capscitor has to be small enough that there's always residual hum. It's not a feature I'd want to use.
 
I've suggested just using Bluetooth modules for this sort of thing. No connection to the outside world.
 
Have one of those that I built using a 1.5 mhz oscillator and a Bluetooth module.
6sn7 as a gain / mixer stage and I think its a 6888 as the tube that puts it all together

Its some octal pentode whatever it is. Its got a 150v gas reg in there to keep power output to legal limits
 
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gadget73 said:
Have one of those that I built using a 1.5 mhz oscillator and a Bluetooth module.
6sn7 as a gain / mixer stage and I think its a 6888 as the tube that puts it all together

Its some octal pentode whatever it is. Its got a 150v gas reg in there to keep power output to legal limits
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I got one of these:

Spitfire AM Medium Wave Transmitter - 6V6 Electronics Company

Community Radio Stations and Vintage Radio Collectors around the world, use the Spitfire AM Transmitter, Part 15 compliant AM transmitter available. Amateur Radio and Electronic Kits, Transmitters, Receivers, Modules and Components. Hobby Kits for Radio enthusiasts.
www.6v6.co.uk www.6v6.co.uk

I use an old cell phone as the source, with EQ adjusted to make it sound a little less thin. 10 foot wire antenna. Tidal or streaming radio as the source. Really sounds great on my old radios. It has to be properly grounded to avoid hum, but it puts put a nice clean signal. Took some experimenting to understand what's the best frequency to use in my house, and to tune the antenna properly.
 
I need to tinker with mine again, I changed it from 1mhz to 1.5 and changed the antenna itself at some point without re-working the matching network. It doesn't peak properly anymore. It also really could stand some audio upgrades. I'd like to implement a limiter / compressor stage to deal with variable source levels a little more gracefully. Probably wouldn't be a bad idea to add some audio bandwidth limiting either.
 
gadget73 said:
I need to tinker with mine again, I changed it from 1mhz to 1.5 and changed the antenna itself at some point without re-working the matching network. It doesn't peak properly anymore. It also really could stand some audio upgrades. I'd like to implement a limiter / compressor stage to deal with variable source levels a little more gracefully. Probably wouldn't be a bad idea to add some audio bandwidth limiting either.
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That one I linked above is really good. It doesn't limit or compress, but if you set the source level right it does work properly, and the LED used to show antenna matching works perfectly. I would have built a kit, but Ramsey is out of business and I'm not sold on the Chinese stuff which is easily available.
 
For me, I just had enough with how un-entertaining AM radio has become. When I started collecting tube radios in the early 90s, there was still a variety of music and I could really enjoy them. Now it's pretty much news, sports, or ethnic stuff. The transmitter brings back enjoyment
 
Oh no question am programming is the pits, I was just referring to my plan to tinker with my homegrown transmitter vs buying one
 
While I do have a low power AM transmitter for playing music through my old AM radios, I'm also very lucky to still have one local AM radio station that still plays music from 3 till 8 PM. It plays 1950s through 1980s mostly, with some 1990s thrown in occasionally :cool:

(This is an old, not updated schedule, there is more music programming than what's listed here)

Screenshot 2026-03-08 103624.png
 
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