[Heathkit] Counter calibration question

Sandy W5TVW ebjr at I-55.COM
Sun Sep 14 13:43:10 EDT 2003


The "counter" portion of the instruyment is just that: a counter!  It will count the
number of
cycles any signal has (within its limits, of course!) regardless of the rate.  To
adjust it to
count its own timebase is futile!  ALL the accuracy depends on how close the timebase
is!
If I were you, I'd just calibrate it to zero beat with 10 Mhz WWV.  The balance in
signal levels of the time base vs. the WWV signal is critical to get the maximum
"beat" audibility
when the two signals are very close together frequency wise.  You will hear a "wow,
wow, wow, wow", the time between the "wows" getting further apart when you are close
to being
dead on frequency.  This can sometimes be heard better when WWV is modulated with the
tone.
Anyway, using 10 mhz instead of the harmonic on 20 mhz.  won't make that big a
difference in the final accuracy of the counter.  The important thing is adjusting
out
the 'sub audible' beats to nil.

73,
Sandy W5TVW
----- Original Message -----
From: <wb8jkr at juno.com>
To: <Heath at listserv.tempe.gov>; <heathkit at mailman.qth.net>
Sent: Saturday, September 13, 2003 8:40 PM
Subject: [Heathkit] Counter calibration question


|   Let me run this by you guys:
|
|  I recently picked up a new frequency counter (Heath IM-2420)
| and I want to calibrate the time base (10 MHz oven oscillator)
| anyway, for some reason its VERY difficult to couple enough
| signal from the time base to my  SX-110 to beat against WWV at 10 MHz.
| I'd really like to beat WWV at 20 MHz for greater accuracy but I can't
| hear the 2nd harmonic of the time base, must be a fairly clean
| oscillator.
|
|  Anyway, how do you think the calibration would be if I connected the
| counter to its own time base? I know that time base inaccuracy would be
| additive to the counter, but wouldn't everything be "balanced out" so to
| speak if I connected the counter to its own time base and adjusted the
| time base for 10.000.000 MHz?
|
| 73, Mark  WB8JKR
|
| Support Amateur Radio, have a Ham for dinner
| Member ARRL, QCWA, OTC, Society of Cable Telecommunication Engineers
| WAS, WAC, WTO, DXCC MIXED, DXCC PHONE, GJDXCC, VUCC 2M, 1st place Ohio
| single op 1988 ARRL  SweepStakes
| Novice 3/71, General 8/72, Advanced 8/78, Extra 8/89
|
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