1924 hartman

[radio nut]

I just purchased a 1924 Hartman battery set radio.
It has 2 sections of signal amp and 2 sections of audio amp. Due to the rarity of 199's I would like to make this a transistor radio.
How do I do that?

[Electronic M]

If those are triodes then look into FETs.

ARC had an article on replacing early triodes with FETs at one point IIRC.

[radio nut]

ARC?
Is this a different forum site?
Does anybody here know how to do this?

[Electronic M]

ARC=Antique Radio Classified....A print publication with a web site (if you've been into tube radio for a few years you should have heard of it).

IIRC the gist is that a N channel FET is the SS equivalent of a triode. Connect gate to grid, Source to Cathode, Drain to Plate, and make sure B+ voltage is below Vds max spec of the FETs being used. Something like a 2N7000 probably would work.

[dieseljeep]

Originally Posted by radio nut

I just purchased a 1924 Hartman battery set radio.
It has 2 sections of signal amp and 2 sections of audio amp. Due to the rarity of 199's I would like to make this a transistor radio.
How do I do that?

Make sure that the interstage transformers are good before you start the conversion. The only battery set I have, both transformers are O/C.

[radio nut]

Both audio transformers show reasonable resistance per section.
What is slowing me down is the lack of a diagram for this set. Not being sure what tubes were in it I am assuming 199's.
So I am currently not positive which tube pin is for heaters or plate/grid.

[radio nut]

Also a 4 tube set with 2 sections of audio would need to be only 1 tube for rf amp and 1 tube for detector,correct?
Would a transistor mentioned earlier do the detectors job or would I need a diode?

[Findm-Keepm]

Originally Posted by radio nut

Both audio transformers show reasonable resistance per section.
What is slowing me down is the lack of a diagram for this set. Not being sure what tubes were in it I am assuming 199's.
So I am currently not positive which tube pin is for heaters or plate/grid.

Have you tried the various magazines over on AmericanRadioHistory for a possible schematic? Most are searchable.

[Olorin67]

most 1920's radios were fairly similar, look at enough schematics and you should be able to find stages that match all or at least portions of your set. Only so many ways to make a triode TRF set.