Olli,
Referring to page 8 in the K3 Owner's Manual (may be a different page
for the K3s):
"Frequency Stability +/- 5 ppm for the TCXO standard; +/- 1ppm for
the optional TCXO."
TCXO-1 and TCXO-3 respectively mentioned above.
ppm means one part per million (1Hz per million Hz which is 1Hz per MHz).
So frequency drift is proportional to the operating frequency.
1ppm at 10-MHz is 10-Hz;1ppm at 28-MHz is 28-Hz
TCXO-1 provides 5ppm (+/- 50 Hz at 10-MHz and +/- 140 Hz at 28-MHz)
TCXO-3 provides 1ppm (+/- 10 Hz at 10-MHz and +/- 28 Hz at 28-MHz)
the basic frequency stability is determined by which TCXO is
installed in your K3.
EXREF "essentially" checks frequency drift of whichever TCXO you have
installed at a fixed time interval of about 4-seconds. It uses a
high stability 10-MHz external signal to compare with the 49.380-MHz
TCXO and corrects the drift that occurs over the 4-second interval.
My measurements of the TCXO-3 show about half the published spec of
1ppm (14 Hz at 28-MHz) and the EXREF limits the drift of the TCXO-3
to about 2 Hz. If I had the TCXO-1 installed, I would expect five
times as much drift.
So which TCXO you install directly impacts frequency stability. The
EXREF reduces that by about an order of five. The EXREF is not the
source of stable LO but merely improves what you have
installed. Does that clear it up?
73, Ed - KL7UW
The question to ask is what amount of frequency stability and
accuracy is important for your type of operations.
Date: Sat, 12 Mar 2016 08:17:32 +0100
From: Oliver Dr?se <[email protected]>
To: [email protected]
Subject: Re: [Elecraft] 10 MHz external reference - GPSDO
Message-ID: <[email protected]>
Content-Type: text/plain; charset=windows-1252; format=flowed
Why would I need the TCXO-3 instead of the TCXO-1 when using the K3EXREF
if the accuracy and stability is provided by the EXREF? Am I overlooking
something here?
Tnx & 73, Olli - DH8BQA
Contest, DX & radio projects: http://www.dh8bqa.de
73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[email protected]
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