[ARC5] [armyradios] BC-221 Testing Results

[Mike Everette]

The BC-221 has harmonics -- uasable ones -- far beyond 20 mc.

I have used both a 221 and an LM to align HF receivers up through the 10 meter band; and have also used them to align low-band FM receivers in the 40-54 mc range, including 6 meters.  When modulated, the LM has about as much, maybe more FM as AM.  Works very well indeed.

I've also used the BC-221 to "net" commercial low-band and 6-meter FM transmitters by listening to the crystal oscillator in the FM rig, or one of its harmonics.  This assumes that one has zero-beat the master crystal in the freq meter with WWV at 10 or (better yet) 15 mc.  A small hole can be drilled in the case (OH, HORRORS!!!!!) to make this adjustment; also, add a plastic tube (Mickey D's straw) inside the unit to keep the tuning tool -- 6-inch screwdriver -- from contacting anything it shouldn't.

With very careful tuning, the LM/BC-221 can even be used to align an FM broadcast receiver front end.

73

Mike
W4DSE

--- On Sat, 11/24/12, Jay Coward <jcoward5452 at aol.com> wrote:

> From: Jay Coward <jcoward5452 at aol.com>
> Subject: Re: [ARC5] [armyradios] BC-221 Testing Results
> To: armyradios at yahoogroups.com, ARC5 at mailman.QTH.net, Milsurplus at mailman.QTH.net
> Date: Saturday, November 24, 2012, 10:48 AM
> 
>  The output should not be a pure sine wave but should be
> rich in hamonics. Even though the LM's and BC-221's have
> adjustments I've never found it nessessary to try to improve
> performance.
>  Another surprise to me was the TS-1 oscillator used with
> the AN/ARR-1 Homing adapter. This is a cavity tuned unit set
> to 245 MHz. It was off by 30 Hz as measured with an Agilent
> spectrum analyzer.
>  Jay 
>  
> 
> 
> 
> -----Original Message-----
> From: J. Forster <jfor at quikus.com>
> To: ARC5 <ARC5 at mailman.QTH.net>;
> ArmyRadios <ArmyRadios at yahoogroups.com>;
> Milsurplus <Milsurplus at mailman.QTH.net>;
> VMARS <VMARS at yahoogroups.com>
> Sent: Fri, Nov 23, 2012 4:32 pm
> Subject: [armyradios] BC-221 Testing Results
> 
> 
>  
> 
> I recently got a new toy, a BC-221-AK with the A-133 AC
> supply and have
> been testing it with modern test gear. Actually, it is
> suprrisingly good.
> 
> Both bands work and put out a couple of volts of RF when
> measured on a
> 'scope with a 10X probe connected to the antenna leads.
> 
> The lower band is an asymmetric pulse waveform, about 25%
> low and 75%
> high. The waveform is not atall clean, but looks like it was
> drawn by a
> drunk with palsey. The upper band is not a bad sine wave.
> 
> When checked in the frequency domain, using the FFT on the
> 'scope, the
> lower band has a lovely comb, extending to well over 3 MHz;
> the upper band
> is also a comb, but with fewer lines, extending to over 20
> MHz.
> 
> If I put the unit in CHECK mode and zero beat against the
> internal crystal
> at 3000, 6000, 12000 kHz, I get 2.99999 Hz on the counter.
> IMO that's
> pretty good after nearly 70 years.
> 
> Best,
> 
> -John
> 
> ==============
> 
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