[RTTY] Antenna and radiation issue

[Phil Sussman]

Hi,

In an attempt to get back on RTTY, I've been able (thanks to the
many fine people on this reflector) to interface by TNC to my
rig, a JST-245.

By necessity my shack is on the second floor and I am currently 
using a long wire antenna (175 feet) and an old (AEA-3000) tuner.

Everything loads up fine and I am able to work SSB without any
difficulty. RTTY is another matter. Every time I key up, the
station locks up... the computer freezes, the TNC has to be
turned off, reset, and reinitialized.

I attributed this to an excessive amount of RF and toward that
end I built a small RF sniffer using a 50uA meter and a few
parts. Needless to say I have a real RFI problem. Even at low
power of about 5 watts, the sniffer meter pegs. I've got about
20 feet of RG-8 that I use for a 'feed-line' and the radiation off
the shield is fantastic. 

I attempted to remove the RG-8 and hook long wire directly to the
tuner. That reduced my radiation by about 20%, but did not solve
my problems. I installed a 'counterpoise' ground system and loading
is sharper, but the problem remains.

Oddly, in SSB operation, the radiation is inconsequential. Only when
I run RTTY does the duty cycle cause a radiation problem. Also, I've
noticed the radiation builds quickly after 5 seconds of operation
from little, if any, to excessive.

CW causes no troubles. 

My thought is that I need to 'move' the RF away from the rig and
hopefully into the antenna.

Any assistance in this matter would be appreicated.

Thanks,

de Phil - N8PS