[MRCA] bC-474 Power Supply

Thu Jun 26 13:49:53 EDT 2025

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

https://www.ebay.com/itm/255028122493?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20250324084321%26meid%3D624173c04f0b40ed92fe3ae7cc3adce8%26pid%3D101949%26rk%3D1%26rkt%3D1%26itm%3D255028122493%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3DRecentlyViewedItemsV2WithMLRPboosterAndUpdatedFeatures_BP%26brand%3DUnbranded&_trksid=p4375194.c101949.m162918&_trkparms=parentrq%3Aad4cc2bb1970a67a962ac35bfffff8cc%7Cpageci%3A9a0640dc-52b3-11f0-bf56-5e3ab2aabd74%7Ciid%3A1%7Cvlpname%3Avlp_homepage

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: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of scottjohnson1 at cox.net
Sent: Thursday, June 26, 2025 12:14 PM
To: w1nzr at cs.com; 'B. Smith' <smithab11 at comcast.net>; 'Tim' <timsamm at gmail.com>
Cc: 'Military Radio Collectors Association' <mrca at mailman.qth.net>
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:

https://www.amazon.com/Aobao-Converter-45V-390V-Capacitor-Adjustable/dp/B09KRL9132/ref=sr_1_9?crid=3COY7ZW60LRT9&dib=eyJ2IjoiMSJ9.2RzlFZ02G0PaRSmRgHt7B_zoVkkok9_gEnEImwlLtqI8GTtaaejE71ttthwWNnkreW65u4u1kitiPlJM3wqegSkClBaiX3PRRLLkrozZeISSgouoeAw_EZki-zKyl9fvXeHyzNLVbim-jI3vlK4tpOLEj8Ml-WBjssGorEokJQ3BTkFD2kLjqo2yN2j4kWurO_HJDGOpjvyQ6AFD1j6FJJafnqYQQVf-tNTuX_9fMBs.NYGFkN4Snkg--fZovzL4nOM5sNJnvVUI0nTpjumw4fM&dib_tag=se&keywords=90-390V+DC-DC+converter&qid=1750953625&sprefix=90-390v+dc-dc+converter%2Caps%2C154&sr=8-9

Shop it around, can be had for less than $10 in quantities.

regards,
Scott W7SVJ

From: mrca-bounces at mailman.qth.net<mailto:mrca-bounces at mailman.qth.net> <mrca-bounces at mailman.qth.net<mailto:mrca-bounces at mailman.qth.net>> On Behalf Of w1nzr--- via MRCA
Sent: Wednesday, June 25, 2025 3:12 PM
To: B. Smith <smithab11 at comcast.net<mailto:smithab11 at comcast.net>>; Tim <timsamm at gmail.com<mailto:timsamm at gmail.com>>
Cc: Military Radio Collectors Association <mrca at mailman.qth.net<mailto:mrca at mailman.qth.net>>
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 <timsamm at gmail.com<mailto:timsamm at gmail.com>> 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 <mrca at mailman.qth.net<mailto:mrca at mailman.qth.net>> 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
[cid:image001.gif at 01DBE69E.DC71AC20]
http://k4che.com/BC474power/BC474Power.htm

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