[MRCA] MRCA Digest, Vol 258, Issue 34

Sat Oct 25 21:23:25 EDT 2025

 ScottI replaced the inverter transistors on the PRC 47 with 2N5884. I have three and PRC 47 and they are all working with the 2n5884’s. Something else to check in the power supply are those electrolytic capacitors, i’ve replaced all of mine. Also, i’ve done all of the mods VOX and verable tuning along with the lower sideband mod.MikeW1ZFB
    On Saturday, October 25, 2025 at 11:42:57 AM EDT, <mrca-request at mailman.qth.net> wrote:   

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Today's Topics:

  1. Power inverter for sale (RODNEY HOGG)
  2. Re: Germanium Transistors (J Mcvey)
  3. D Cell in Parallel CAUTION (B. Smith)

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Message: 1
Date: Fri, 24 Oct 2025 15:25:16 -0400 (EDT)
From: RODNEY HOGG <radio_man at wbsnet.org>
To: mrca <mrca at mailman.qth.net>
Subject: [MRCA] Power inverter for sale
Message-ID:
    <1725586894.503464736.1761333916242.JavaMail.zimbra at wbsnet.org>
Content-Type: text/plain; charset="utf-8"

I found in my cache of stuff something I never knew I had. Have a power inverter, made by Abbott Electronics, Model A1173. 
Is solid state with 24-30VDC input with 115VAC output at 400 cycles. rated 1.57Amps. Is brand new OS. Weighs 5.5lbs. 
Anyone need/want such a critter? Offer? Neat item. 
Rod 
K0EQH 

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Message: 2
Date: Fri, 24 Oct 2025 20:55:33 +0000 (UTC)
From: J Mcvey <ac2eu at yahoo.com>
To: <scottjohnson1 at cox.net>,  <rl.boltz at mhsdesign.com>,
    <mrca at mailman.qth.net>
Cc: cca at groups.io
Subject: Re: [MRCA] Germanium Transistors
Message-ID: <1824744531.257438.1761339333601 at mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"

I would look for the least leaky ones of the bunch.

Sent from my undisclosed bunker location

On Wednesday, October 22, 2025, 4:39 PM, scottjohnson1 at cox.net wrote:

The characteristics are of minimal concern in a low frequency inverter, they operate cutoff and saturated, so linearity is not really an issue. These days, most of these inverters could be served by a single pair of power MOSFETs. I don?t think that is the point.? There is huge satisfaction to be had making this equipment work as designed, within the bounds of reason.? As far as ?rot? goes, there was a problem with early Germanium semiconductors with ?purple Plague?? wherein gold bond wires on aluminum metallization formed an intermetallic compound (rather than a true alloy) which eventually destroyed the device by virtue of its poor conductivity and very low melting point.? Aluminum wire bonds eliminated the problem.? However, I have dozens of devices that are up to 70 years old that are still percolating along (ARC-58, URC-32, AIC-10 intercoms, PRC-21s, etc.? Some devices do and will fail, but don?t write all of them off unless there is evidence of a real problem.? Hope thi
 s sheds some illumination of the topic.

 ?

Scott W7SVJ

 ?

From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of rl.boltz at mhsdesign.com
Sent: Wednesday, October 22, 2025 11:38 AM
To: mrca at mailman.qth.net
Subject: [MRCA] Germanium Transistors

 ?

Do NOS germanium transistors get ?rot? or go bad from age?? I need to replace the invertors in a PRC-47 and I have 5 NOS original germanium transistors.? All test vastly different. I expect variations as not matched sets but these are WAY off.? I suspect at least 60 years old and maybe much more.

 ?

Ron Boltz

K3tzj

 ?

 ?
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Message: 3
Date: Sat, 25 Oct 2025 11:42:03 -0400
From: "B. Smith" <smithab11 at comcast.net>
To: Military Radio Collectors Association <mrca at mailman.qth.net>
Subject: [MRCA] D Cell in Parallel CAUTION
Message-ID: <95f0d52b-ea77-4a73-bd52-d00789df181f at comcast.net>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

 ??????? Several members are evidently using two (2) D cells in parallel 
to power the filament chain of receivers such as the GRC-9, BC-611, and 
GRC-109. I've mentioned a "Melt Down" problem with this procedure 
numerous times on my BC-611 and BA-48 page.
 ??????? Over the years I and several other membershave experience 
multiple instances of D cell battery packs consisting to two Alkaline 
Manganese Dioxide cells wired in parallelcreating very high 
temperatures. We call this phenomenon "Melt Down."In BC-611's the case 
gets so hot you could not pick up the radio if you touched the area 
where the battery pack was inserted. Fortunatelyeach time the "Melt 
Down" occurred the radio was either in the field or on the bench and not 
being stored or on the shelf.
 ???????? In each case the manufacture was Duracell or Energizer. It is 
mentioned briefing in their safety sheets that the "Batteries may 
explode or leak, and cause burn injury, if recharged. . ." I hate to 
mention brand names but these manufactures make an excellent battery and 
thus their cells have enough energy to cause "Melt Down" which occurs 
when one battery is trying to charge the other battery.
 ??????? In most cases two D cells are overkill in powering the filament 
chain of our military reeivers when one battery wouldsuffice. I 
recommend that if you insist on using two cells in parallel that you 
insert the batteries only for the exact time that you need the receiver 
to be powered and that you monitor for over heating. Remove the 
batteries when not in use.Do not store the battery pack on the shelfin a 
parallel configuration. It has been reported that batteries that were 
exposed to high temperatures in the sunlight prior to use were prone to 
"Melt Down."

Safety sheets for these batteries should bedownloaded and read.

K4CHE
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End of MRCA Digest, Vol 258, Issue 34
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