[ARC5] [MRCA] [Milsurplus] Vintage LF/MF Fun with my BC-453B

[Mark K3MSB]

Hi MIke

Here's a screen capture from my SDR from 17 Nov 2025  0200 EST:

It shows the USB for VQK and HK, both on 332 Kc
VQK is in Washington DC and HK is in Hickory NC.

[image: image.png]

The USB Frequencies are:

HK 333.018 Kc
VQK 333.028 Kc

That's a difference of 10 Hz.

At my QTH,  VQK is a boomer,  and HK is weak.   Without a very narrow
filter, I cannot clearly hear HK.

73 Mark K3MSB













On Fri, Nov 21, 2025 at 4:07 PM Mike Feher <n4fs at eozinc.com> wrote:

> Hi Mark – I am curious, what can you possibly hear thru a 7Hz or even a 20
> Hz audio filter? Thanks & 73 – Mike
>
>
>
> Mike B. Feher, N4FS
>
> 89 Arnold Blvd.
>
> Howell NJ 07731
>
> 908-902-3831
>
>
>
> *From:* mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> *On
> Behalf Of *Mark K3MSB
> *Sent:* Friday, November 21, 2025 3:28 PM
> *To:* Hubert Miller <kargo_cult at msn.com>
> *Cc:* ARC5 <arc5 at mailman.qth.net>; Milsurplus at mailman.qth.net; Military
> Radio Collectors Association (mrca at mailman.qth.net) <mrca at mailman.qth.net>
> *Subject:* Re: [MRCA] [ARC5] [Milsurplus] Vintage LF/MF Fun with my
> BC-453B
>
>
>
> HI Hue
>
>
>
> Sorry for the late reply.
>
>
>
> I'm blessed to have some friends that keep their eyes out for tuning knobs!
>
>
>
> The HP-23 provides 250V B+.  For my full up SCR-274N setup, I use the same
> HP-23 but have a 1K 10W resistor in line to drop the voltage to about 190
> to 200V.   I'll do that for this setup when I find some time.
>
>
>
> The Blue Box under the HP-23 is my 28V supply.   I got it at an estate
> sale for $20. It was originally a 12V supply, but it was nicely constructed
> and had dual metering.   I replaced the 12V transformer with a 28V
> transformer and added a regulator and pass transistor. I think I can source
> 5A from it, but in any case it is more than sufficient for any ARC-5
> (generically speaking) receiver.   I have the output filtered, and it's
> pretty clean.
>
>
>
> The box under the headphones is a Timewave DSP-599zx noise filter / audio
> processor.  I"ve done what I call "iron man" listening -- no external audio
> processing -- and after doing it a few times I find it's much easier on the
> ears to be able to adjust the audio bandwidth down to 20 Hz.  By the way,
> the little blue box to its left is a Ratzlaff 7 Hz audio filter!    I've
> had to use it many times with my SDR or modern receivers.
>
>
>
> 73 Mark K3MSB
>
>
>
>
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