[TowerTalk] PL259 Insertion Loss?

[Frederick Vobbe]

With all due respect, Dan, in design you have to weigh all losses, and 
one way is not to over-complicate designs with multiple connectors.

However, on my station I come out of the rig, to a low-pass filter, then 
to 4-port coax switch, then up to a Heath antenna switch, finally to the 
antennas.

The dB/loss question came up and we debated it to death in our club, 
till one enterprising soul suggested we measure the signal levels.  A 
station transmitted a carrier on 7, 15, and 28 mHz, and it was measured 
in the configuration above, and with a coax from the antenna direct to 
the rig.  We ended up repeating the tests by dropping power to where the 
signal was barely detectable.  The result was; while the loss through 
the system could be measured, and that measurement was very minimal, 
from the operator's chair there was no difference between (3) devices & 
(8) PL259 connectors, and a single RG-8 with (2) PL259 connectors.

Now, if you're talking 6-meters and above, (especially 70cm and above), 
then there is a compelling argument for lessening PL259s in the design.  
But at that point I would be thinking of LDF50-4 or LDF50-5 with Type-N 
connectors to mitigate losses.

Another critical component is length and quality of line, especially 
when line is cut and connectors attach with appear reflective.  A lot of 
things weigh in on this issue, but all have to be considered.

I'm not discounting losses in PL259s.  But I think there is a time to 
knit-pick, and a time to lean back and operate.


Fred/W8HDU