Thanks Bob,
My late night calculating in my head was off by factor of ten
5ppm at 10-MHz is +/- 50Hz and at 30-MHz 150-Hz
And I forgot that the TCXO-03 actually performed at 0.5ppm so one got
ten times better stability suing the TCXO-03.
I reviewed my actual notes for testing with the TCXO-03 + EXREF
stabilized by an OCXO at 10-MHz having +/-5 E-12 short term stability.
I have a K3/10 so power output was set to 10w for the tests.
I measured 28 MHz with -1.5 Hz offset, and
50-MHz with -2.5 Hz offset, tests repeated the next day within 1-Hz.
Measurements per my EIP-538 frequency meter which was externally locked
to a Rubidium source of +/-5 E-11. [I was a beta tester on the EXREF]
That effectively brings the K3 down to .05ppm. On 28-MHz I figure I'm
within 2-Hz which is great for running VHF/UHF transverters that can add
up to 10-Hz drift running modes like FT8 or JT65.
On 2m using my K3 with 25w transverter, I see total upward drift of 7-Hz
after running 30-minutes of JT-65. One wants to limit max drift to
20-Hz running digital modes.
At 432 and 1296 my transverters have PLL local oscillators so only drift
is from the K3. Note I run the K3 transverter I/F at 1mw so there is
virtually no heating inside the K3 to cause drift.
Running a K3 with 100w might yield different results. My understanding
is that the K4 has the EXREF as standard, if one wants to use an
external frequency standard (correct me if that is not true).
73, Ed - KL7UW
On 3/31/2022 3:35 PM, elecraft-requ...@mailman.qth.net wrote:
From: Bob McGraw<rmcg...@benlomand.net>
To:elecraft@mailman.qth.net
Subject: [Elecraft] TCXO
Message-ID:<4b5a4813-135d-f484-171d-be99a71a3...@benlomand.net>
Content-Type: text/plain; charset=UTF-8; format=flowed
The TCXO is the reference frequency for about everything that takes
place in the radio.? It is the master clock.? If it is incorrect, then
everything else is incorrect, for the most part.
A 5 ppm TCXO, or 5 parts per million, can have an error of ±250 Hz on
6 meters.?? Where as a 0.5 ppm TCXO can have an error of 25 Hz on 6
meters.?? It just depends on how accurate and stable you desire your
radio to be.
Oh, the frequency read-out on the front is just that, a read out.? It is
not a frequency measurement of the exact frequency. Many will put their
radio on 14.255.000 and swear it is on that frequency.? But with a 5 ppm
TCXO it could be ± 71 Hz.? Where as with a 0.5 ppm it would be ± 7
Hz.? Of course one must consider crystal and component ageing and
perform very easy calibration procedure at regular intervals.? I check
and adjust mine once a month and can maintain ± 2 Hz or or better.
I ordered mine with the 1 ppm TCXO with F/W corrected to 0.5 ppm.
73
Bob, K4TAX
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
