On 11 Jun 2005 11:22:42 -0700, "mike" wrote:

Our system operates on either of 2 channels near 470MHz. Channel 1
transmits via a repeater located in the hills a few miles away, while
channel 2 is direct.

communications are still poor on channel 1.

What does "poor" mean?

Assuming that the repeater is fine now, the problem seems to be more
related to the individual busses.

This needs more description. If just ONE bus operates fine, then you
don't have a problem with the repeater.

Over the course of time our mechanics
have swapped-out radios, mics, and probably antennas as well. Given the
nature of the problems and my previous (limited) experience with CB, my
suspicion is that the antennas on the busses need to be tuned.

Commercial mobile is usually quite bullet-proof and is far more
tolerant through over powered gear. The antennas would have to be
seriously whacko, like twice/half their usual size. In other words,
visual inspection with a ruler and basic understanding of wavelength
is enough (a whip roughly 16cm tall).

I used to tune my CB antennas with an SWR meter and get good results. I
understand the basics enough to be able to do that and could probably
teach our mechanic as well. However, since I have no experience with
UHF I don't know if there's more to it with UHF over standard CB and if
there is more equipment required than an SWR meter. I am just having a
real difficult time paying $80.00 an hour for someone to do something I
used to do quite easily.

Hi Mike,

Sounds cheap at $80/hr. Frequently service problems are reducible to
connections. In your case this would be transmission line
connections, connectors, and antenna base clamping (screws or nuts).
Again, all of this is easily determined through visual inspection and
a pocket full of screwdrivers and pliers.

73's
Richard Clark, KB7QHC