[ARC5] Transistorized LM

[Rich Post]

Some years ago, I acquired an HP-400D (AC VTVM) that had its 6CB6 tubes
swapped with Fetrons.  Here's my old notes on it:
<https://people.ohio.edu/postr/bapix/HP400D.htm>

Rich KB8TAD

On Sun, Aug 31, 2025 at 8:02 PM Mike Feher <n4fs at eozinc.com> wrote:

> I believe Bell Labs also made some. 73 - Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell NJ 07731
> 908-902-3831
>
> -----Original Message-----
> From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On
> Behalf Of Tom Lee
> Sent: Sunday, August 31, 2025 6:10 PM
> To: arc5 at mailman.qth.net
> Subject: Re: [ARC5] Transistorized LM
>
> Hi Hue,
>
> After a little googling with variant spellings of 'tubestor', I found
> this: https://www.qsl.net/kh6grt/page4/tubesters/tubesters.htm. Could
> this be what you were thinking of?
>
> That site not only has schematics for tubesters, it's got a wealth of
> FETRON info and related articles. Even if it turns out not to be the
> tubestors you remember, reading the material is a great way to burn the
> long weekend. ;)
>
> -- Cheers,
> Tom
>
> On 8/31/2025 2:34 PM, Hubert Miller wrote:
> > I just did a quick Google search on 'tubestors' and lo, there does not
> > seem to be any info jumping right out at you. Maybe later i should try
> > another engine. I was curious how they handled dropping the B+ down
> > from tube range to FET range. I have some lit "somewhere" but only
> > like advertising, nothing revelatory about the actual innards circuit.
> > These didn't seem to be on the market very long  did they ? In Frank
> > Zappa's words, they were gone like the elephant's footprints in the
> ocean.
> > -Hue Miller
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