[time-nuts] Vintage Frequency Measurement
kb8tq at n1k.org
Sun Feb 12 22:08:43 EST 2017
The GR is a classical wave meter that works off of a tuned circuit and a broadband
detector. The BC-221 works on an entirely different principle and has no ability at all
to run in the mode that the GR operates in.
> On Feb 12, 2017, at 9:13 PM, Alan Hochhalter <alanh137 at gmail.com> wrote:
> I have a General Radio Type CAG-60098-A Precision Wave Meter made for Navy
> Department - Bureau of Ships according to the nameplate. According to
> Wikipedia that would date it between 1940 (when bureau of ships was
> created) and 1966 (when abolished). It has an inductor in sort of a
> "hockey puck" labeled 16-50 kc that plugs into a socket on the front panel.
> Inside is a very nicely made variable capacitor with a vernier drive. It
> has been a while since I had it apart, but there is a diode in series with
> the meter and not much else as I recall. The meter scale is 0-200
> (microamp?) and the capacitor scale is 0-75 with no other marking. I have
> no manual, but I assume there were other inductors for different frequency
> ranges with a calibration chart to interpret the 0-75 reading. It must
> have been made to test transmitters by tuning for peak reading on the meter
> and determining the frequency from the dial reading.
> a different Alan (KE7AXC)
> On Sun, Feb 12, 2017 at 5:47 PM, Alan Melia <alan.melia at btinternet.com>
>> Hi Dan yes that is 5e-6 about all an unstabilised (temp) AT could hold for
>> any period. I guess there were no WWV or MSF signals around then. When a
>> good source was available off-air it was possible to do better than that.
>> In service it was probably "dont waste time trying to better the minimum
>> requirement. The transmitter you are looking for wont be that accurate or
>> In 1960s I saw several BC-221s in the racks at the Rugby LF and HF
>> stations acting as standby frequency sources (VFO) for rapidly running up a
>> transmitter on an unusual frequency (not a normal route) for which they did
>> not have a crystal available.
>> ----- Original Message ----- From: "Dan Rae" <danrae at verizon.net>
>> To: "Discussion of precise time and frequency measurement" <
>> time-nuts at febo.com>
>> Sent: Sunday, February 12, 2017 11:11 PM
>> Subject: Re: [time-nuts] Vintage Frequency Measurement
>> To put BC-221 things in perspective, the 1 Mc/s reference crystal was
>>> adjusted, according to the manual, to within 5 c/s...
>>> Things have come a ways since!
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