BC-221-T w/built-in PS

[K5WLF]

Went to the Cowtown Hamfest (Fort Worth, TX) yesterday and came home with a BC-221-T for $25. It's in real good condition, has the original calibration book and the dial works smoothly and zeroes perfectly with the "Hundreds" window.

However, it has a built-in AC PS. Not some cobbled-together POS, but a very well made unit with a 5Y3GT rectifier and a VR-106 with US Navy markings on the base, looks like a couple of big 'transformer style' chokes and an oil cap. I haven't taken the PS out of the battery compartment yet. It may well be home-brew because the tube sockets are secured with screws rather than rivets, but if it is, it's well-done home brew.

The SCR-211 manual mentions nothing about an optional AC PS for the units. Has anyone here ever heard of a 'field mod' for the BCs, or do I have the result of someone's creativity in the shop?

ldb

[W7TFO]

In my early broadcast days those were a popular item for techs, and all of them I saw had been converted to AC power just as yours has been.  Some were neat, some were really haywire.

I have one very nicely done by an unknown soul as a wooden-cased VFO.

dg

[Ralph W3GL]

It was SOP (standard operating procedure) at 4th & 5th etchlon maintenance facilitys to put AC power into the BC221 meters for fixed location use, eg, HQ locations, etc. .

Also, if you were using the meter with an SCR 199/299/399, etc, you had 110 volt/60 cycle AC available via the PE 95 supplied with these systems...While powering the BC 610's, that gen set also supplied power for the commanders coffee pot and HQ lighting chores.

I don't remember the source of the supplys, but they were available through channels...

[KE6DF]

There was an optional external supply for LM series frequency meters (the Navy equivalent to the BC-221).

I've see pictures of them and thy show up on epay now and again.

The real PITA with the LM meter is finding the power connector.

I have a real nice NOS unit and I hate to cut into it to wire in power and drill a hole to take power out -- but can't find the connector.

[WB6NVH]

There were several "original" AC power supplies which were usually found with the 221's used in depots on service benches.  I have had a couple of them.  The ones I had, had an on-off switch on the AC cord because of the way the power switch on the 221 is configured (for batteries.)  The original AC supplies are usually MFP coated so that's one way to tell that they are not homebrewed.  There were also a couple of different metal cabinets usually used in depots with the 221, although I have had the green wood cased versions with military AC supplies inside as well as the black wrinkle ones.

The LM had several AC configurations as well.  Like the BC-221, it seems to be hard to find the data on those setups.

[W2VW]

It was SOP (standard operating procedure) at 4th & 5th etchlon maintenance facilitys to put AC power into the BC221 meters for fixed location use, eg, HQ locations, etc. .

Also, if you were using the meter with an SCR 199/299/399, etc, you had 110 volt/60 cycle AC available via the PE 95 supplied with these systems...While powering the BC 610's, that gen set also supplied power for the commanders coffee pot and HQ lighting chores.

I don't remember the source of the supplys, but they were available through channels...

Hey Ralph,

    What did they use to for measurement in WW1?

[W7TFO]

Probably a GR wavemeter...

73dg

[WB6NVH]

I was thinking the same thing, one of those GR wavemeters in the wooden case, but I am not sure GR was in business yet (?).  But, don't forget, WWI gear involved spark transmission and a miss is as good as a mile as far as resonant frequency of a spark transmitter tank circuit.  Thus precision wasn't a particularly important item.

[W7TFO]

I don't see why not, they got started in 1915.  Reportedly the longest-running electronics company in the US.

73 dg

[K9PNP]

Since I have a 221 in my BA collection, I looked through my references on this.  Yep, nothing at all in the TM 11-300 manual for it, like you said.  I have seen them with AC supplies.  At least one was obviously a milspecs item since it had the yellow/brown anti-fungal [etc] coating on everything, but that was in the 60's and was in the posession of an old commo-type Warrant Officer.  The Brits had an AC supply for their versions, but appear to have been a post-WWII item.  They called it a 'Power Unit Type 7262'.  See:   http://www.royalsignals.org.uk/photos/bc221ak.htm.

The Soviets likewise had AC supplies for their CH4-1; an exact copy of the BC-221.  Not much info available on those.  All I could find was at:  http://wftw.nl/scr211/scr211.html

I have seen 'for sale' items listed with AC supplies such as this: 
[Military BC-221-AH Frequency Meter s/n 5302. This is the nicest and most complete one of these that I have ever seen. It's in the olive drab wooden case and comes with the original AC power supply PS-221AC s/n 1893, headset extension cord and HS-30 headset. Very good or excellent cosmetic condition. With original manual. A complete set of spare tubes and spare crystal is inside the unit. The serial number on calibration book matches meter SN. Untested. As-is. Tubes are 1 6X5, 1 VR150, 2 6SJ7Y and 1 6K8. $35]  from AM Radio 3 Mar 05.  Can't find a reference to the PS-221AC anyplace.

Wish I could find my home-made cross-refernce book; might have some more info.  Have not seen it for some time.

[w8khk]

Hey Ralph,

    What did they use to for measurement in WW1?

I don't think Ralph is quite an old enough buzzard to comment on WW1 first-hand, but then again, when I recall his previous avatar, I could be mistaken.......

[WU2D]

I finally got hold of a couple of these, one in a metal case with black crack and one in a plywood case painted green. The black one had a an AC PS inside that I "improved" by going solid state and even adding a regulator FET.

Beside the obvious frequency setting capability...The device is very useful for netting simple CW rigs like regens and simple transmitters and it makes a handy on-air sidetone. The problem with regens is knowing if your transmitter is zero beat to the station you hear in the regen! Any transmitter easily overloads or pulls the regen. The BC-221 solves this problem very elegantly.

Let's say you want to work CW on 3550 kHz. First you dial in the frequency using the calibration book. Then you tune the VFO for zero beat in the phones (or speaker with a transformer) on the BC-221. Then key down the TX again and now off tune the BC-221 high (or low) till you get a 1 kHz beat.

Let up on the key. Now tune the regen till you hear the weak carrier from the BC-221 and set it for zero beat. The regen is now set 1 kHz high and the BC-221 is also set 1 kHz high so it will act as a sidetone. When receiving it will be zero beat but actually I just turn mine to the XTAL position temporarily during RX.

Mike WU2D

[Ralph W3GL]

Rick,

You know, I can't remember what I had as my avatar before the passport photo was stuck in here  

Some times just recalling what I had for dinner yesterday becomes a chore...

Ask your dad, it's just a byproduct of aging, I suspect

Edit, 1/25/10:   Oh yes, now I recall, that old buzzard with his lower lip pulled
over his noise... Of course that was just joking, I still have an almost full complement of teeth so that feat is not possible with this face.  

Photo is W3GL in 2002