[ARC5] The not-so humble BC-221/LM-xx frequency meters.

[Richard Knoppow]

    Hearing goes down pretty low as you can prove with a pair of high 
quality headphones and a clean oscillator.
    Finding a zero beat when the frequencies are very close requires a 
third oscillator such as the BFO on a receiver. When the two test 
signals are very close the BFO audio beat can be heard waxing and 
waning. You can determine a beat by ear or on the S-meter when the beat 
is a few seconds long.
     A care when beating to WWV is to be careful you don't zero on the 
modulation frequency. Sometimes it difficult to know when you are on the 
carrier. Wait until the unmodulated period to be sure. A sharp crystal 
filter will help because it can be set on the carrier which is always 
stronger than the sidebands.

On 12/24/2016 2:27 PM, Bill Cromwell wrote:
> Hi Les,
>
> Peoples' hearing response varies all over the place. You don't see me
> pooh-poohing the audiophools because I cannot prove they don't hear the
> difference. I do have a lot of doubts. I play music and I have seen
> numbers as low as the 20s in cps and as high as 100 or more. When we
> hear '60 cycle' hum we are supposedly hearing a harmonic of 60. Maybe
> some of us can hear dog whistles, too. I used to interpolate between the
> two points where I lost the note on the low side and on the high side.
> Then the bobbling, wobbling S-meter. Then I got a scope and thought I
> was in hog heaven. Most recently I have been using the soundcard
> software as I described. I am also planning to look into the gps
> signals. I suspect that if I have a gps reference signal and a signal
> "in the wild" I need some means to measure the relationship between the
> wild signal and the reference signal (gps) if I am to tame the wild signal.


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