[ARC5] BC-221 and LM on eBay

[Richard Knoppow]

    I now can't rember if the modulator on the BC-221 version 
that has one works with the detector on. If it does it would 
allow "three oscillator tuning"
  a way of getting very close zero beats (fraction of a cycle). 
When close to zero beat the modulation can be heard to wax and 
wane. So, one can get within a fraction of a cycle of exact zero 
beat even with magnetic headphones that have poor low frequency 
response. I think most LM and BC-221 meters do not have a 
modulator. I am lucky because I have one that does.
    This same technique works for any radio receiver with a BFO 
or a regenerator set to oscillate.

On 3/28/2022 10:41 AM, David Stinson wrote:
> In my personal, humble opinion- no judgement
> on what others think about this:
> 
> If one needs sub-cycle accuracy, using a -221
> or LM is probably not productive.  WWII aircraft
> receivers were intentionally designed with
> broad selectivity specifically to address the
> problems of keeping flights of rigs "close enough"
> with mass-produced (though well-produced)
> freq meters in the hands of quickly-trained
> "Radio Mechanics."  Though an excellent design and
> carefully crafted, they are still
> "an instrument of their time."
> 
> If one needs sub-cycle accuracy and stability,
> signal generators of that calibre are widely
> available and relatively inexpensive.
> 
> If one wishes to enjoy using a classic piece one
> has refurbish himself for zero-beating the local
> AM net or aligning the broad IFs of a WWII
> receiver, the LM and -221 are "just the ticket."
> 
> Enjoy the romance of driving a "Ford Model-A"
> or "57 Chevy" for what it is, without expecting
> it to be a 2022 Audi or Corvette.
> 
> Comparing LM/221 performance using modern
> standards is the same error modern academe
> commits comparing 19th to 21st Century ethics
> (without the political agenda, of course).
> 
> YMMV, IMHO, etc.
> 73 OM DE Dave AB5S
> 

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL