Trig is probably “fussy” because they think you should deliver the
transponder power to the antenna, not use it to heat the cable. I
think it's significant that Trig doesn’t specify the use of RG-58 at
all.

Aircell cables are European, they aren’t easily available in the US,
and would be expensive if you could order them. Attenuation for
Aircell 7 (the best cable recommended by Trig) is 6.9 dB per 100 feet
at 1 GHz. US made LMR300 is even better, it has an attenuation of 6.4
dB per 100 feet at 1 GHz. LMR240 comes in with a bit higher
attenuation at 8.0 dB per 100 feet at 1 GHz.

As for cost, 15 feet of bare LMR240 is $13.35. You can get a complete
LMR240 cable made with a TNC at one end and a BNC at the other for
only $30. Doesn’t seem outrageous.

-John

On Feb 6, 10:55 pm, "Paul Remde" wrote:
Hi,

The Trig TT21 and TT22 manual is also quite fussy about transponder antenna
cable. But it important to note that many of the "long run" antenna cables
they recommend are extremely expensive.

I recommend mounting the transponder unit (it is separate from the control
head) as close to the antenna as possible. When that is done I have
received customer feedback that RG-58 cable works fine - with all required
tests passed with flying colors.

Paul Remde