[NCARC] 145.115 repeater experiment improvement-- need your help

[Steve's email]

Hi folks-

We have some interesting news for you and would like to enlist your help in
understanding a change made in the 145.115 repeater setup.

Eric Slutz (N0EUS - our tech committee lead) and Dan Magro (W7RF-- "Radio
Dan - www.radiodan.com ") and I did some additional measurements on the
145.115 repeater system today.  Dan helped us confirm our previous
measurments that show we have *significant* noise coming in through the
antenna and feedline (over 1 uV incremental broad-band noise signal coming
into the repeater input). He also helped us determine that the SWR of the
antenna/feedline system was a bit high but not excessive (around 2:1).

Meanwhile Eric came up with a valuable experiment idea that we tried today.
We mounted Eric's Diamond X500HNA antenna on the roof of our repeater
building near our APRS antenna and connected this up to the 145.115
repeater. (We ok'd this as a temporary setup with George AB0SF who is also
checking with his supervisor).

This experimental setup had almost a 1.1:1 SWR as well as considerably less
noise and a better coverage patttern.  This system performed so much better
than the existing antenna in on-the-air tests, SWR, and noise measurements
that we've decided to leave this setup in place until we can sort out what's
wrong with the existing antenna system.  This new setup is installed as if
it were a "permanent" installation so that it can withstand winds, cold
weather, etc.  We hope we can diagnose the problems with the existing
system, because we can probably get considerably better performance with the
right antenna and good feedline up 140 feet on the tower.

In the meantime, would you please help us with some over-the-air tests using
the 145.115?  Please travel to known shadow areas / use minimum power levels
and see if you notice a difference.  Please report your findings to this
reflector if you can, or to Eric, Dan, and myself.  (To use this reflector
you need to register and also make sure you send the email in plain text
format.... sign up at http://mailman.qth.net/mailman/listinfo/ncarc

'73

-Steve, N7GN
NCARC President