[K4RY] iGate and Digipeater up and running for K4RY

[Kris Kirby]

On Thu, 31 Jul 2014, John Hung wrote:
> Vertex (Yaesu) VXR-5500.  John Hung

> > On Thu, 31 Jul 2014, John Hung wrote:
> >> The 2-m repeater is the Yaesu FTR-2410 I believe. I have a PDF of the 
> >> manual on my office computer. You're right, the 444.80 has gone deaf 
> >> for me as well. Another item to check out.

Y'all may consider installing a shorted 1/4-wave stub on each 
single-band radio station. It will prevent precipitation static and 
couple static fields to ground. I'd recommend checking them across a 
large temperature range before committing them to the installation. 
Don't forget to factor for velocity factor, and use attenuators between 
a MFJ analyzer and the stub. The MFJ is prone to VCO pulling as a result 
of a changing load impedance. 

Lightning doesn't like to make abrupt changes or angles, so coils of 
coax (held together with Velcro, not tie-wraps (causes discontinuities in 
impedance at those locations)) form HF chokes.

Lightning behaves like a large square-wave DC pulse with many harmonics 
up into the megahertz. I live near several 1,000 ft towers, and watching 
a storm on a HP-141T (analog) spectrum analyzer is amazing and 
enlightening. You can scan the whole range from 100 KHz to 1250 MHz in a 
single sweep and see the effective environmental low-pass filter. 

If you're colocating repeaters or VHF/UHF stations with a HF station, 
make liberal use of ferrites for chokes and put loops in the coax to act 
as chokes as well. But remember, take a direct path to the central 
grounding block or panel -- you have to encourage lightning to go where 
it is best handled, not where it might want to visit. 

It also helps if the antennas a DC-shorts like the DB-224 and DB-420. 
The DB antennas also have the advantage that the antenna is attached to 
the mast, but the mast is conductive aluminum. If the mast is properly 
bonded, most of the lightning current should pass down the mast into the 
support structure and/or grounding system. Of course, aluminum and 
copper do not combine very well for very long. (Never use galvanizing 
spray on copper wire! I learned that one the hard way!) 

--
Kris Kirby, KE4AHR
Disinformation Architect