There were some articles regarding BC-221 calibration
in the late 40s early 50s QSTs.

Pete

You should be aware that each BC-221 and the other heterodyne
frequency meters had its own individually plotted calibration book so
using one from another meter wasn't an accepted practise.

Still, if you don't have any calibration book anything is better than
nothing.

73,

Michael, W1RC

On Sat, 20 Dec 2008 22:49:15 -0500, "Tio Pedro"
There were some articles regarding BC-221 calibration
in the late 40s early 50s QSTs.

wrote:
You should be aware that each BC-221 and the other heterodyne
frequency meters had its own individually plotted calibration book so
using one from another meter wasn't an accepted practise.

Still, if you don't have any calibration book anything is better than
nothing.

73,

Michael, W1RC

On Sat, 20 Dec 2008 22:49:15 -0500, "Tio Pedro"
There were some articles regarding BC-221 calibration
in the late 40s early 50s QSTs.

There is an excellent article with photos of the original equiupment
used to calibrate the BC221.It appeared in the Christmas 2008, Issue No.
116 of the UK Publication Radio Bygones. (www.radiobygones.co.uk
www.radiobygones.com)

The article is based on a reference in the May 1944 edition of
"Electronics" (U.S. magazine???)by Philco Engineers which described the
calibration procedure in detail

Those people were really clever!!!

Lionel L Sharp

On Sun, 21 Dec 2008, wrote:

You should be aware that each BC-221 and the other heterodyne
frequency meters had its own individually plotted calibration book so
using one from another meter wasn't an accepted practise.

Still, if you don't have any calibration book anything is better than
nothing.

73,

Michael, W1RC

We went through this already.

Like I said when this thread started, all the warnings about them
being useless without the calibration book dates from a time when
calibrating them would have been at the least tedious, and of course
few had any good frequency standard.

Pete mentioning that there were articles about calibrating them
yourself is interesting since I've never seen any such thing,
clearly at the cusp of when they were available people did
go to the trouble, but later nobody bothered.

Nowadays, it's a different matter, since anyone with a frequency
counter can live without a calibration book, or at least make
up a calibration book far easier than sixty years ago. They likely
have access to a very good frequency standard too.

Michael VE2BVW

On Sat, 20 Dec 2008 22:49:15 -0500, "Tio Pedro"
There were some articles regarding BC-221 calibration
in the late 40s early 50s QSTs.

Michael Black wrote:

Nowadays, it's a different matter, since anyone with a frequency
counter can live without a calibration book, or at least make
up a calibration book far easier than sixty years ago. They likely
have access to a very good frequency standard too.

Precisely. The thing is, with a good counter you don't need a BC-221
any longer.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."