[Milsurplus] [ARC5] Transistorized LM

[boeing377 at gmail.com]

Years ago the late ARC 5 collector Henry Engstrom showed me a very
interesting swap meet buy, a fully solid state BC 348 in non working
condition. It had been gutted and was full of very nicely done green
fiberglass printed circuit boards with solid state components. Zero
documentation or history. I didn’t want to take it on as a repair project
as I saw it as a time sink rabbit hole. Wonder who made it and where it is
now? Hopefully somebody got it. Gorgeous work inside.

Mark
AF6IM

On Sat, Aug 30, 2025 at 10:52 PM Hubert Miller <kargo_cult at msn.com> wrote:

> I think the Fetrons main purpose was to replace valves in Telco test
> equipment. So you're going to see FET-6AK5 but not FET 6BA6 and 6BE6 for
> example.
> Remember 'tubestors' for the Collins S-Line ? There doesn't seem to be a
> lot of info about for these. An ongoing subject of curiosity for me.
> I recall a few paragraphs in 'Amateur Radio Techniques' book by Pat
> Hawker, RSGB, where he told about a reader's conversion of a single
> conversion Eddystone to solidstate. Said the radio did not even need
> realignment when done. Of course the main benefit is those RF oscillators
> stay near one temp, so good bye to most of the drift.
> Years back there was a fellow selling a couple BC-611 talkies on Ebay.
> This was maybe, good heavens, 10 - 15 years ago. Each
>  ~ $400 and they sold. I copied what i could from various sources later (
> thank you ! ) but i have nothing on the transmit side. The 'conversion'
> used all single gate JFETs and consequently i would not call it real smart.
> I wrote the seller and quite politely asked for info on the transmitter
> side. As you know, you do not get 300 mW input power to an AM final using
> small signal FETs at 12 VDC. So i wondered what he did abt that. Got no
> answer, so i assume #1 he was tired of the subject, didn't care to deal
> with my imposition ( altho i did give my ham call also ) or #2 the
> conversion was similar to receiver, kind of dumb, just very basic and with
> resultant very low transmit power, but enough to demonstrate it worked, and
> he realizes  that and prefers not to revisit the subject, or #3 both of
> above are true, or #4 none of above are true and my guesses miss entirely
> the mark. My money is on #2.
>
> I am VERY interested in transistor replacements for receiver tubes. Make
> that, !  Of course for single conversion receivers it's a piece of cake,
> but when you get into double conversion and such you want to be more
> careful about 'gain distribution'. I have not yet attempted this myself.
> But i tell you what, i hate being asked to pay $$ big bucks for some
> Wehrmacht equivalent of a 1T4 or 6SK7, some tube you can get for a couple
> bucks up, here. I also of course refuse to adapt any radio to use "more
> modern" tubes. That is really inappropriate in the transistor era.
>
> I read here about a solidstated R-392. I would REALLY like to know more
> about that and see the schematic !!
> -Hue Miller
>
>
>
> Sent from my Galaxy
>
>
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