[Milsurplus] BC-312

[David Olean]

Jim

It has been awhile, but I put it inside a tight aluminum can with 0.01 
feed thru caps in and out. The can looks like an IF transformer and is 
well shielded. In addition I had to wrap input and output wires with low 
frequency ferrite cores. I think it was 75  material, which is a low 
frequency core. 31 would also work well I think. I had to put a lot of 
stuff in there to limit the energy.  The Chinese switchers are terrible 
for RFI.

Dave K1WHS

On 10/26/2022 11:30 AM, Jim Whartenby via Milsurplus wrote:
> Interesting, did putting the converter in a metal can clean up the 
> hash? What type of ferrite bead and feedthrough cap did you use?
>
> I've been thinking along the same lines, putting the converter in a 
> decent metal box to simulate a dynamotor and use the same mount in an 
> ARR-15.
> Regards,
> Jim
>
> Logic: Method used to arrive at the wrong conclusion, with confidence. 
> Murphy
>
>
> -----Original Message-----
> From: David Olean <k1whs at metrocast.net>
> To: David Stinson <arc5 at ix.netcom.com>; milsurplus at mailman.qth.net 
> <milsurplus at mailman.qth.net>
> Cc: ARC-5 <arc5 at mailman.qth.net>
> Sent: Wed, Oct 26, 2022 10:18 am
> Subject: Re: [Milsurplus] BC-312
>
> I tried a similar DC -DC converter from China on my RA-10 receiver. I
> located it inside the radio and found that I had to shield the bejeesus
> out of it to keep the digital hash from the receiver input! It ended up
> inside a metal can with bypassing and ferrites all over it.  My unit was
> quite noisy. It is especially troubling when your receiver covers the
> long wave frequencies. Mine ran at 210 volts DC with a 28 VDC primary
> input. Be prepared to shield it in the radio.
>
> Dave K1WHS
>
> On 10/26/2022 8:07 AM, David Stinson wrote:
> > I've ordered a couple of these to try:
> > https://www.amazon.com/dp/B08SLFSRL6
> > Claimed to source 100mA at 100-230VDC
> > with 4-15V input.
> >
> > I've powered some small receivers with some
> > of the older High-Voltage inverters. The
> > "Yellow ones" have some birdies and they
> > top-out at about 45mA- enough to run
> > an ARC-5 at low B+.
> >
> > We'll see how noisy is this new one.
> >
> > GL OM ES 73 DE Dave AB5S
> >
> > P.S.  Another interesting one:
> > https://www.amazon.com/dp/B0992GCCSK
> > If you have a small receiver or QRP
> > transmitter that sips no more than 40mA,
> > this one has a filament voltage regulator
> > and will do HV 150-420V.  Has feedback indicating
> > that the MOSFET  (IRF840) is a bad Chinese knock0ff
> > which can die early (no heat sink compound)
> > and if you replace it with a known-quality FET,
> > it will then work for you.
> >
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