The trick is what are you powering??? The receiver want just ninety volts at low current but the transmitter is another story. I have a BC-474 up next in line after I finish
off a bucket full of MAB/DAV radios and am thinking of maybe using that device for the MAB/DAV stuff as opposed to fifteen nine volt batteries in series been thinking of maybe something like this for the transmitter side of the BC-474
Was a time I would not consider purchasing this stuff and just roll my own but now days you can buy a finished DC to DC converter for way less then you can build one.
Mr. Smith been doing this stuff for years now and see that he has built up more BC-474 then I have had hot meals and he has been looking at the problems associated with this
technology. Think his most eloquent solution has been adapting the power supply from the old GE Executive series radios and would love to do that but short of GE Execs right now.
Crazy thing about this hobby, quite often we will spend mor time, money and effort to achieve a result then makes any sense! Good example although it has nothing to do with
the subject is that I spent twice what a Xiegu G-90 cost to buy a GRC-215 backpack transceiver although the G-90 will do everything and maybe more than the GRC-215 there you go, insanity in action! Tell you what though, that green Millpack, about the size
as a PRC-74 fills a need that the little Chinese set just cant.
Ray F/KA3EKH
From: [email protected] <[email protected]>
On Behalf Of [email protected]
Sent: Thursday, June 26, 2025 12:14 PM
To: [email protected]; 'B. Smith' <[email protected]>; 'Tim' <[email protected]>
Cc: 'Military Radio Collectors Association' <[email protected]>
Subject: Re: [MRCA] bC-474 Power Supply
All-
This is my go-to for the last several years when I need a B+ supply for a RX or small TX. Powering my BC-474 with it. Makes a great capacitor charger for a spot welder. I also built a PP 6BQ5 car audio amp,
and powered it with a pair of these:
Shop it around, can be had for less than $10 in quantities.
regards,
Scott W7SVJ
From:
[email protected] <[email protected]>
On Behalf Of w1nzr--- via MRCA
Sent: Wednesday, June 25, 2025 3:12 PM
To: B. Smith <[email protected]>; Tim <[email protected]>
Cc: Military Radio Collectors Association <[email protected]>
Subject: Re: [MRCA] bC-474 Power Supply
Seconding Tim's thank you Breck....yeoman service as we cling to the trailing edge of technology, work on things no one really cares about and take the unimportant seriously...
Cheers,
Brown / W1NZR
On Wednesday, June 25, 2025 at 04:44:54 PM EDT, Tim <[email protected]> wrote:
Thanks for all the work you did to document all this Breck. I don't have a '474 but your ideas have pretty universal application.
Cheers!
Tim
N6CC
On Wed, Jun 25, 2025 at 12:56 PM B. Smith via MRCA <[email protected]> wrote:
I've revised power supply information on the BC-474.
Revised sections include info on : Connectors, The FL-10 filter, Use of a GN-45, Dynamotors, Inverters, Battery Bias.
The section on Dynamotors features notes and design info by Al N3FRQ and a Dynamotor list compiled by Robert WA5CAB is also included. Another solution to the Receiver Bias problem using a small battery is also presented.
K4CHE
http://k4che.com/BC474power/BC474Power.htm
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