[MRCA] bC-474 Power Supply

Thu Jun 26 15:31:15 EDT 2025

My questions are, how much RF hash do these produce, and can they be 
used directly as a receiver B supply without a lot of extra filtering?
AL - N3FRQ

On 6/26/2025 1:49 PM, Ray Fantini via MRCA wrote:
>
> 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 
> <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 
> <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 <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>; Tim <timsamm at gmail.com>
> *Cc:* Military Radio Collectors Association <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> 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> 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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-- 
ARK Sig Block Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/
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