Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Ron Wagner wrote:
"/Cw RIT" will run close to $1000. Way overpriced for what it is,
but they just didn't make that many of them. Unfortunately, RIT is
just about a necessity for CW operation today, since so many use very
narrow filters and don't know how to tune around with their
transceivers looking for signals! Just in case you're thinking of
adding RIT to a TR-4CW, that's not very simple either. The PTO in
the "RIT" model has an RIT input, but none of the other 4 Series
do. The 'RIT' PTO is the same as used in the TR-7.
There is an article from June 66 QST for RIT on the TR3. I put it on
my TR3 with very little effort. I took it off when I sold it. I used
the remote VFO connector for several of my connections. I did not
follow the article exactly. I do not know how much RIT it gave me,
but it did work well or SSB.
Basically it put a varactor diode on the PTO tube. I think the newer
Drake PTOs have a "lug" for use with RTTY which could be used for the
RIT function connection. All this is on memory, and mine is not like
it was at one time. Any way have a look at the Drake museum, I think
the article is there. If not, I think I still have a copy and can get
it scanned.
73,
Ron
Ron -
The earlier tube PTOs were fairly easy to "RIT", because the tube was
accessible and it didn't take much delta C to move them around. The
solid state PTOs were another story as there wasn't any easy way to
shift the frequency without going "inside" the PTO, which is not a good
idea for the inexperienced. The RTTY terminal on the PTOs was designed
to shift the frequency about 900 Hz or less with an external capacitor
to ground. The problem was that a large enough capacitor to get the
typical 2-3 kHz shift for RIT became a significant source of temperature
instability that was NOT compensated by the PTO tempco design.
The PTO in the TR-4Cw/RIT (and TR-7) had an internal varactor tapped
onto the inductor which gave the necessary shift with much less
capacitance. The "RTTY" terminal on the side of the PTO was used as the
RIT terminal since by that time most had gone to AFSK for HF RTTY.
So yes, it "could" be done. But not an entirely satisfactory solution,
especially for the solid state units.
73, Garey - K4OAH
Atlanta
Drake R-4C Service Information CD
http://www.k4oah.com
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