Bob -
The C-Line does fine for RTTY. The transmitter has a jack on the back panel marked RTTY that when
shorted shifts the carrier a bit to ensure that both tones (2125 - 2975 Hz 850 Hz shift,)were
passed through the LSB filter unattenuated. It was originally designed when we were still using 850
shift, but is no longer of any value for today's (2125 - 2295 Hz 170 Hz shift) and should be left open.
I ran multiple 4 Series transmitters on RTTY for some years, at full power and with transmissions of
30 minutes or more. You have to run them just UNDER the ALC threshold (just below where the output
levels off) as you increase GAIN. PA tubes lasted a couple of years that way, with 'end of life' at
100W output max on 14.075 MHz. Obviously a small fan is a BIG help, either on top (blowing UP) or
on the rear panel of the PA cage (blowing OUT).
For contest type transmissions (excepting 10 minute CQs!) I wouldn't hesitate to use full power,
about 340 mA. If you make long CQs, I'd back it down to about 300 mA. (~ 100W output) and the PA
tubes will last 'forever'.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Robert Fish wrote:
I have been thinking about using my C-line for the RTTY contest this weekend.
How do I set the transmit audio (gain) level. Do I set it the same as SSB where
the peaks are about 150ma? I am not set up here for FSK, so its going to be a
sound card affair.
Any general advice for C-line RTTY?
Thanks,
Bob K6GGO
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