[Milsurplus] Unique BC-221 Conversion

[howard holden]

His schematic appears to be incomplete. This looks like a typical 30's-40's MOPA diagram but he has two each controls for the osc and amp plates, yet there are only one cap in each. Also there are some apparent antenna trim controls on the top but nothing on the schematic. It goes straight to a link coupled output. Also there's a "plate current" bulb on the top, but not on the schematic.  Curious about that because the meter is switched between the two tubes, and there's no separate plate power-on switch. Looks like he only used the BC-221 cabinet, gutted the rest.

The keying, yes it puts a lot of V on the key, but many early Novice rigs used that. As long as you keep the cathode side to the lower (hot) contact on the key, chances of an accidental contact are small. Lived with this method of keying for years. Still do on some rigs!

Of course this does beg the question of what happened to the "real" BC-221.......

Howie WB2AWQ

On 10/26/2016 6:49 AM, Ray Fantini wrote:
Not a bad looking job, like the name tags. Too bad there are no interior pictures.  The keying system looks to be fun having lots of high voltage on the key contacts but understand that’s the way things were done back then. One little relay would have gone a long way in helping.
I just finished reading how on the old land line telegraph circuts it was not uncommon to run sometimes hundreds of volts and can see where that can get hairy.

Ray F/KA3EKH

From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Hubert Miller
Sent: Tuesday, October 25, 2016 4:51 PM
To: Glowbugs <tetrode at googlegroups.com><mailto:tetrode at googlegroups.com>; milsurplus at mailman.qth.net<mailto:milsurplus at mailman.qth.net>
Subject: [Milsurplus] Unique BC-221 Conversion

Here’s a unique “conversion” of a BC-221 frequency meter.
http://www.ebay.com/itm/112174815013?rmvSB=true
with a slight modification, it became a 6AG7 + 807 ham transmitter.
-H




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