I keep a gifted LM-8 (a Navy version of the BC-221) on my workbench as a frequency generator.  Extremely accurate.  Nearly 80 years old, I think but I can't find the production date.  I also have a nice BC-221 and a third unit (Army version) awaiting restoration.  I really like these old units.
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On Wed, Aug 27, 2025 at 10:50 PM kgordon2006 <kgordon2006@frontier.com> wrote:
I really like my -AKs too. I find them to be unusually accurate and stable for bring 70 years old.

Ken W7EKB



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-------- Original message --------
From: JAMES FALLS <radio-tuber@att.net>
Date: 8/27/25 18:40 (GMT-08:00)
To: Mark K3MSB <mark.k3msb@gmail.com>
Cc: Ken Gordon <kgordon2006@frontier.com>, ARC5 <ARC5@mailman.qth.net>, List Milsurplus <milsurplus@mailman.qth.net>
Subject: Re: [ARC5] [Milsurplus] BC-221AK Question

Yes! The -AK is my favorite of the -221 series. Love it!

Funny anecdote: Mine came to me via a friend who’d stopped at a wide spot on a rural road here in NorCal to relieve himself. He spied it 20’ down the hill (out of range 😛😁). It was the innards, no case. A bit dusty from its trip down the hillside. 

I checked it out and it worked perfectly! Just a scant few PPM off of WWV when enclosed and warmed up. I found a non-battery cabinet and ran it with a separate PSU. I aligned and debugged all my milsurplus radios with it. 😎👍

Jim Falls K6FWT 

On Aug 27, 2025, at 17:34, Mark K3MSB <mark.k3msb@gmail.com> wrote:


Hi Ken

>> The cap is part 9-2, not 0-2 and it is supposed to be 0.001 uF.

Yes, my typos.   Too lazy to roll over to the bench and get my glasses........     :-)

<image.png>


.... and thus the motivation for my question....

<image.png>


<image.png>


The internal HB Power Supply was a "Widow-Maker" Special......with leaky caps!!!

I will rebuild the PS tomorrow and power it up (after dressing the connections associated with the replacement components.....and using the correct parallel capacitor.

73 Mark K3MSB




On Wed, Aug 27, 2025 at 7:46 PM Kenneth G. Gordon <kgordon2006@frontier.com> wrote:
On 27 Aug 2025 at 18:56, Mark K3MSB wrote:

> I have a BC-221 whose ID plate says  BC-221E.   It is not an E
> variant.
> From the tubes, front panel controls, and TM11-300,  I think it's the
> AK variant.

I have two -AKs here: unfortunately. in storage, not in the shack. :-(

> Looking at the front panel,  what is supposed to be behind the two
> antenna connectors?

Well, only ONE is an antenna connector: the "other" one is a ground connector...or should be.

> I tried discerning it from TM11-300.   I think it's supposed to be a
> 150 H Choke (Part 24) in parallel
> with a 0.01 uF cap (Part 0-2).

The cap is part 9-2, not 0-2 and it is supposed to be 0.001 uF.

>    Can anyone confirm?

Well, a 150 H choke would be physically fairly large for a "small" choke. I would have to go to my storage building and open one of my -AKs up to check, and cannot do that just now.

I hope Wayne can help. If all else fails, I'll make a run to my storage and take look as soon as I can.

BTW, the -AK version is one of only two other versons which include AF modulation capability. None of the others have that. This makes the -AK a fully functioning signal generstor.

Ken W7EKB
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Frank Barnes
www.W4NPN.org
Chapel Hill, NC
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