It is currently Sun Aug 20, 2017 7:02 am

Mystery "Radio"

Phones- Digital, Analogue, PABX, Receivers, transmitters & military equipment.
 
Posts: 1931
Joined: Mon Jul 25, 2011 12:12 pm
Location: Burghfield, Reading, UK

Mystery "Radio"

Post by Brianc » Mon Aug 20, 2012 7:46 pm

Hi all
An auction house is offering this item as a "Military Radio Set". It looks more like a grid dip meter or similar. Does anyone know exactly what it is? I see that there is a verneer on the units dial so it must be for measuring - or must it?
Attachments
Mystery Lot (Small).jpg

 
Posts: 5926
Joined: Sat Jul 23, 2011 8:19 pm

Re: Mystery "Radio"

Post by CTV » Mon Aug 20, 2012 7:50 pm

I took the liberty of enhancing so others may find it easier to help.

Chris
aa.jpg

 
Posts: 340
Joined: Tue May 01, 2012 11:23 am

Re: Mystery "Radio"

Post by turretslug » Mon Aug 20, 2012 8:59 pm

I believe it's a BC221 frequency meter, of US manufacture circa WWII vintage- as with much of this stuff, must have cost a fortune to make, but singularly business-like in presentation.

Colin.

 
Posts: 7156
Joined: Sun Aug 14, 2011 11:02 am
Location: Co. Limerick

Re: Mystery "Radio"

Post by Michael Watterson » Mon Aug 20, 2012 9:26 pm

Good stab Brian, as part of the feature of most dip meters (grid or gate!) is to turn off the oscillator and use it as a "wavemeter" (basically a calibrated crystal set!). Which is all you had till frequency counters could do MHz rather than a few 10s of Kilohertz.

You can use it as a very deluxe crystal radio :)

 
Posts: 472
Joined: Wed Aug 17, 2011 5:03 pm
Location: Aylesbury, Bucks.

Re: Mystery "Radio"

Post by GlowingAnode » Mon Aug 20, 2012 10:31 pm

Definitely a BC221 super-het frequency meter.
Recognised it from the first upside-down partial shot!
And I bet the range switch is seized up.
Rob.

 
Posts: 1931
Joined: Mon Jul 25, 2011 12:12 pm
Location: Burghfield, Reading, UK

Re: Mystery "Radio"

Post by Brianc » Tue Aug 21, 2012 8:56 am

I assume then, the there were calibration charts to go with the kit which translated dial readings to frequency. When you say "superhet frequency meter", Rob, does this mean that it has a reasonable amount of electronics inside?

 
Posts: 7156
Joined: Sun Aug 14, 2011 11:02 am
Location: Co. Limerick

Re: Mystery "Radio"

Post by Michael Watterson » Tue Aug 21, 2012 9:05 am

Yes,

Certainly much more than a simple wavemeter.

Did you check BAMA for the manuals?

 
Posts: 472
Joined: Wed Aug 17, 2011 5:03 pm
Location: Aylesbury, Bucks.

Re: Mystery "Radio"

Post by GlowingAnode » Tue Aug 21, 2012 12:36 pm

Brianc wrote:I assume then, the there were calibration charts to go with the kit which translated dial readings to frequency. When you say "superhet frequency meter", Rob, does this mean that it has a reasonable amount of electronics inside?


Yes, you're absolutely right Brian.
Without the calibrated charts, the meter is pretty much useless.
Internally there's very little, two or three valves (6sk7?) and a (1Mc/s?) octal based crystal.
A popular mod in the 60's was to use these as a VFO for a transmitter, good stability after 20 mins or so warmup. The tuning mechanism is exceptionally well made, as is the whole of the meter. Unfortunately to get to the band switch, which seem to have a habit of rusting up solid, requires dismantling virtually the entire instrument. The knobs have a special splined Allen key, that should live inside in a little clip.
Rob.

 
Posts: 7156
Joined: Sun Aug 14, 2011 11:02 am
Location: Co. Limerick

Re: Mystery "Radio"

Post by Michael Watterson » Tue Aug 21, 2012 5:20 pm

I presume with an accurate modern generator you could make charts?

 
Posts: 472
Joined: Wed Aug 17, 2011 5:03 pm
Location: Aylesbury, Bucks.

Re: Mystery "Radio"

Post by GlowingAnode » Tue Aug 21, 2012 9:04 pm

Yes, indeed you could, a tedious process as the book contains several thousand calibration points.
Interesting related article here; http://jproc.ca/ve3fab/bc221.html
Rob.


Return to Telephones, Telegraphy, Amateur comms & Military equipment



Who is online

Users browsing this forum: No registered users and 1 guest