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RF Signal Amplifiers for Antique TRF Radios

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Jordan Dobrikin

New Member
Hi
Looking for Circuits/designs to replace Tubes (Triodes) in Antique/Vintage Medium Wave TRF Radios and Regenerative Receivers.
Exploring the idea of of using Radio on a Chip picking up the signal at the input to the Detector and not shunting RF to ground.
Not Tube substitution of an individual tube but replacing all tubes to use lower, safer voltages.
Thanx
73 de Jordan ve7jjd
 

MikeMl

Well-Known Member
Most Helpful Member
What is a"radio on a chip"?

Can you use RF JFets to substitute for tubes on a per-stage basis?
 

audioguru

Well-Known Member
Most Helpful Member
In the olden days there were few radio stations so their frequencies were spread out. Then a simple radio could tune in the station you wanted. But today there are many radio stations all across the band and close together. A simple and cheap old circuit might pickup a few stations at the same time or be overloaded by so many stations. Why not make a modern circuit instead?

There is a "radio on a chip", the old TDA7000 or its replacement the TDA7088. It is in an FM "radio" sold cheaply at The Dollar Store. It comes with a headset and battery so the actual radio is free. Its performance is awful.
 

dr pepper

Well-Known Member
Most Helpful Member
Do you mean a Zn414?, such a device could be used as a pre amp detector, and connected to the input of the detector diode/triode.
You might as well build a complete rx with a Zn414 and Ne602 mixer osc as all the tubes in older sets use 150v + anode voltages.
Unless maybe you look into some newer tube car radio's, the later ones worked with very low anode voltages, some I hear ran from 12v.
 

RadioRon

Well-Known Member
Hi
Looking for Circuits/designs to replace Tubes (Triodes) in Antique/Vintage Medium Wave TRF Radios and Regenerative Receivers.
Exploring the idea of of using Radio on a Chip picking up the signal at the input to the Detector and not shunting RF to ground.
Not Tube substitution of an individual tube but replacing all tubes to use lower, safer voltages.
Thanx
73 de Jordan ve7jjd
Hi Jordan
I'd like to help, but not sure what you are asking. If you don't plan individual substitution of tubes, then are you considering replacing the entire RF section? If so, doesn't that sort of take away from the value of the vintage receiver? Not sure I understand.
 

BobW

Active Member
The old tube TRF radios usually had 3 tuned RF stages. The ZN414 and MK484 receiver-on-a-chip IC's have only a single tuned RF stage. These are cheap low performance IC's for making cheap low performance radios. Why not just fix up the original radio? It'll be a lot easier than messing around with a retrofit circuit, and you won't destroy the value of an antique.
 

dr pepper

Well-Known Member
Most Helpful Member
Yes thinking about it unless its a real cheap set if its a trf then it will be quite old and not really a good candidate for modification.
 
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