• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

I want to build an AM Tube Tuner

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autoteck1

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Joined 2006
I built a receiver about 15years ago, found most of the information in a old "Radio Handbook" 1940 something, I used differant stages from differant receivers accordinng to the tubes I had on hand. I hand wound coils on pieces of p.v.c. and a.b.s. pipe using the basses of dead tubes so I could make multi band plug in coils, The charts are in the book "turns ratio x coil diameter for differant bands. you can scrounge alot of parts fairly cheap on e-bay if you buy "Parts receivers" , you don't need alot for a simple superhet,if I remember you can do it with three tubes. pentagrid converter,duo diode triode, and audio output. one 455kc i.f. transformer . with the right tubes you don't need a power transformer. This may help http://www.pmillett.com/Books/audels.pdf
 
Miles Prower

Miles Prower

Member
Joined 2005
dolphin-hsl.com
Nige64 said:
this site has lots of radio circuits to look at, simple and complex ones. trf radios are easy to make, if you use at least 2 tuned circuits and an simple rf amp the performance can be suprising right up into the shortwave band.
Click to expand...

TRF xcvrs are best implemented with solid state. The gain requirements are best answered with op-amps, and of course, active BPFs. Getting 100+ db(v) of gain is going to require just e-ssssssssss loads of VTs, and make for a huge stability headache. :spin: It's tough enough when using solid state, but you do have the possibility of isolating sensitive stages with active decouplers.

Best to go with either a regen detector (done right, these can really perform quite well) or a superhet (so you can split the gain between RF and AF). I would go with this design from a previous post, with one reservation: ditch that front end RF amp (6SK7 stage). For the AM BCB, you don't need that, since at these low frequencies the noise riding in on the antenna is going to be in excess of mixer noise anyway. Front end amplification isn't required above 40M, and only at 40M if you are blessed with an unusually quiet QTH (which is becoming harder and harder to find -- even in the middle of the Outback, you have a lot of noise coming from electronic fences). For most locations, forget front amplification unless you're at 10M and below.
 
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