Paul
For idea 3, a pair of 74LS90 or similar /10 chips will do it
The absolute frequency instability at 13.6MHz may be worse than at
136KHz from the rig, depending on what mixing / multiplication is
involved in getting from the internal references
If it is the result of a mixing product with an unstable element
within the transceiver it should be the same regardless of frequency in which
case dividing will help a lot
Mark GM4ISM
-----Original Message-----
From: N1BUG
Sent: Monday, December 31, 2018 1:59 PM
Subject: LF: Bad news / help request
So, the latest SlowJT9 test is completed. I regret I was not able to
run one night on 630m as planned.
I used a QRP Labs Ultimate 3S beacon transmitter for these tests.
Yesterday I checked my ability to use JT9-5 for QSOs and found that
I have none! My FT-2000 transceiver has too much drift to be of any
use on JT9-5 and is very marginal even for JT9-2. What a huge
disappointment, though it did not come as any surprise.
I can think of several ways to solve this but am not sure any of
them can save some part of this winter season:
1. Add insulation and a heater to the FT-2000 TCXO area. I will try
this but I am not convinced I can make enough improvement. The drift
is really ugly!
2. Replace the FT-2000 TCXO with an outboard programmable GPS
referenced oscillator, for example a Leo Bodnar unit. The trouble
with this is I do not have sufficient knowledge or experience to
know what kind of problems might be encountered. The GPSDO is enough
of an investment to kill any and all other attempts at a resolution
if I am unable to make it work.
3. Use a divide-by-100 circuit with the FT-2000 operating at 13.6
MHz instead of a LO/mixer converter from 10 MHz. This should reduce
drift to the order of 0.1 Hz, probably quite acceptable. So far I
have not found a divide-by-100 circuit using a modern/available part.
4. Run away from the junk FT-2000 completely, using audio to 136 kHz
converter for Tx and 136 kHz to audio converter for Rx. This is
finally the direction I want to go but there seems to be much
learning left to do and a lot of building. It's probably not a
solution which can be completed in time for this winter season.
If anyone has experience in any of these areas and is willing to
share knowledge, please get in touch with me. This may be the last
solar minimum for me, and I would like to make some LF/MF DX QSOs
before these incredible conditions fade away.
73,
Paul N1BUG
