[ARC5] A.C. Modified BC-348

[Rich Post]

Mike is correct relative to the ease of use of the 25Z5 with a transformer
designed for directly powering the BC-348 filament string at 24-28 volts.
The instruction sheet says Signal Corps.  Did Hallicrafters produce both an
Army version and a Navy version?

My EP-298 power supply uses a 5Y3 rectifier and has the Navy acceptance
stamp.
<https://people.ohio.edu/postr/bapix/BC348Q_3.htm>

Rich KB8TAD


On Sat, Aug 28, 2021 at 12:08 PM Michael Hanz <aaf-radio-1 at aafradio.org>
wrote:

> Schematic attached.  There were apparently two different rectifier tubes
> used in the EP-298 Halli supply - initially a 5Y3GT, then a 6X5GT-G - which
> has a separate cathode independent of the filaments.  It is not hard to
> anticipate the eventual substitution of a 25Z5 to eliminate the filament
> winding in the transformer...
>
> No "safety" issues with that design.
>
> On 8/28/2021 10:41 AM, J Mcvey via ARC5 wrote:
>
> A 25Z5 implies a "series string/ hot chassis circuit.
> The BC348 design does not lend itself very well  to a transformerless
> power supply.
> Then again, Hallicrafters was famous for grounding one side of the AC
> supply to the chassis!.
> This kind of mod is unsafe, IMO.
> However, safety did not seem to be a big concern "back in the day"...
>
> On Saturday, August 28, 2021, 12:29:46 AM EDT, Hubert Miller
> <kargo_cult at msn.com> <kargo_cult at msn.com> wrote:
>
>
> Here's a 348 i found in my stash. The rectifier tube is a 25Z5, which
> means a drop -in supply with minimum mods. Unfortunately tho, the cabinet
> top has been aerated. The PS has no markings really except for this on the
> tube area shield:
> "TESTED GOOD 11/10/ 45 ROB". Too early to have hit the surplus stores, so
> this must be a gov't mod.
> -Hue Miller
>
>
>
>
> Sent from my Verizon, Samsung Galaxy smartphone
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> --
> Michael Hanz - KC4TOS
>
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