Gentlemen,

I work for a student transportation company using UHF radio
communications. While I have played around with CB radios several years
ago I have no experience with UHF.

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.

For most of the last school year we have operated on channel 2 as
channel 1 wasn't working. A company recently came out (not following
known company authorization proceedures), and apparently repaired a
faulty repeater. Our company was charged about $185.00 for parts and
over $600.00 for labor. The rate worked out to be $80.00 per hour over
7.5 hours. Not only does this seem a wee bit steep to me, but the
communications are still poor on channel 1.

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

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.

Mike

mike wrote:

Gentlemen,

I work for a student transportation company using UHF radio
communications. While I have played around with CB radios several years
ago I have no experience with UHF.

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.

For most of the last school year we have operated on channel 2 as
channel 1 wasn't working. A company recently came out (not following
known company authorization proceedures), and apparently repaired a
faulty repeater. Our company was charged about $185.00 for parts and
over $600.00 for labor. The rate worked out to be $80.00 per hour over
7.5 hours. Not only does this seem a wee bit steep to me, but the
communications are still poor on channel 1.

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

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.

Mike

$80 per hour isn't a bad price if the work is good. UHF requires more
expensive instruments than CB, they amortize that in the labor costs --
in other words that $80 per hour is for the guy _plus_ the equipment.

Assuming the radios in the busses are in good shape (you could send them
out for servicing and alighnment/checking for much less than you could
have the guy come out and do it) you are left with antennas and cabling.
I wouldn't expect that it's _just_ the antennas - coax can be pretty
lossy at those frequencies, if it's been beaten up it'll show.

So get an SWR meter that'll work reliably at 470MHz, and try adjusting
some antennas. Try replacing coax as well, and if either fix seems to
work then keep it up.

--
-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim Wescott wrote:
$80 per hour isn't a bad price if the work is good. UHF requires more
expensive instruments than CB, they amortize that in the labor costs --
in other words that $80 per hour is for the guy _plus_ the equipment.

Thanks, Tim. I am familiar with such issues, although I've had no
reference points for this type of work. If that is the prevailing rate
for UHF work then I'll accept that.


Assuming the radios in the busses are in good shape (you could send them
out for servicing and alighnment/checking for much less than you could
have the guy come out and do it) you are left with antennas and cabling.
I wouldn't expect that it's _just_ the antennas - coax can be pretty
lossy at those frequencies, if it's been beaten up it'll show.

That's where I was headed with this. I have no desire to replace
qualified service companies or personel, rather, it seems worthwhile to
look into the feasibility of moving some of the more routine service
requirements in-house. If it's not practical for us to tackle the
antenna tuning/coax/connections ourselves, then we'll just have to deal
with that.


So get an SWR meter that'll work reliably at 470MHz, and try adjusting
some antennas. Try replacing coax as well, and if either fix seems to
work then keep it up.

Thanks. I was concerned about there being some differences in the
process that I was unaware of between CB and UHF. My limited
understanding of antennas leads me to think that the principals remain
the same and therefore the process should as well. Nevertheless, it
seemed appropriate to ask.

Mike

Thanks. I was concerned about there being some differences in the
process that I was unaware of between CB and UHF. My limited
understanding of antennas leads me to think that the principals remain
the same and therefore the process should as well. Nevertheless, it
seemed appropriate to ask.

Mike

The principal is the same, but remember you are dealing with frequencies
about 20 times higher so what you are use to will be multiplyed by 20. That
is if you were cutting off an inch at a time theh you only need to cut off
about 1/8 of an inch. Also make sure the SWR meter will work at the higher
frequency. One desinged for a higher frequency will work at a lower
frequency just fine if you can generate enough power for the pickup. One
for a lower frequency will not work on a higher frequency as the pickup will
start approaching a large portion of a wavelength. Also with lossey coax
(which most all are at 400 mhz, the swr will be masked so a 3:1 or so at the
antenna will show up as almost a perfect match at the transmitter end.

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

Richard Clark wrote:
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.

Thanks, Richard. As I was hoping would be the case.

Mike

Mike,

Without knowing you, I have to only guess at your previous "CB"
experience, and in doing so, will guess that it is a far cry from the
knowledge and experience a good LMR technician has. Commercial radio is
not CB! Only guessing from the description of your system that you gave,
that is is poorly maintained, at best, and that the repeater had probably
been neglected for quite some time? Several hours of labor would not be
prohibitive, under those circumstances.

Assuming you can properly solder/crimp, and install RF connectors,
I'd guess that you probably can save some money by doing some of the more
basic work yourself. However, you will need more than a CB type SWR
meter. I'd suggest a Bird Model 43 with the appropriate slug for your
frequency and power. That will set you back at least $300.00+. Also,
you probably ought to purchase some good quality connectors, antennas,
and antenna cable/NMO installation kits as I expect you will find several
of the busses needing them.

Good luck trying to do it yourself.

Ed K7AAT

Ed wrote:
Without knowing you, I have to only guess at your previous "CB"
experience, and in doing so, will guess that it is a far cry from the
knowledge and experience a good LMR technician has. Commercial radio is
not CB! Only guessing from the description of your system that you gave,
that is is poorly maintained, at best, and that the repeater had probably
been neglected for quite some time? Several hours of labor would not be
prohibitive, under those circumstances.

Thanks, Ed. Of course I am a bit out of my element on this and that's
why I made it clear that I have no experience with UHF, and only
limited experience with CB. I was not directly referring to making
repairs on repeaters and the like, only antenna tuning and such.


Assuming you can properly solder/crimp, and install RF connectors,
I'd guess that you probably can save some money by doing some of the more
basic work yourself. However, you will need more than a CB type SWR
meter. I'd suggest a Bird Model 43 with the appropriate slug for your
frequency and power. That will set you back at least $300.00+. Also,
you probably ought to purchase some good quality connectors, antennas,
and antenna cable/NMO installation kits as I expect you will find several
of the busses needing them.

Thanks for the suggestions. Is $300 entry/mid for a basic meter of this
type?

Mike

Thanks for the suggestions. Is $300 entry/mid for a basic meter of
this type?

Mike


Actually, the $300.00 will barely get you the wattmeter at a
reputable communications product dealer such as Tessco. I believe the
individual elements would run around $65.00. You can see Tessco's
listing at:

http://www.tessco.com/products/getPr...o.do?sku=43948

More information on the Bird model I cited can be found at:

http://www.bird-electronic.com/produ...uct.aspx?id=81

There are other units that would work well, too, such as the Telewave
model 44 watt meter. That one costs around $390.00 but doesn't need
separate elements.

Again, a reminder, these are professional tools and you still need to
know how and what to do when you find an antenna problem, and what proper
parts to obtain.


Ed K7AAT

----- Original Message -----
From: "Ed"
Newsgroups: rec.radio.amateur.antenna
Sent: Saturday, June 11, 2005 8:44 PM
Subject: Service Help


Thanks for the suggestions. Is $300 entry/mid for a basic meter of
this type?

Mike


I have a spare Bird 43 meter with the Peak Modification (your choice of "N"
or UHF" connectors) and the leather carrying case that I could sell you for
that price.

This came out of Cellular industry component repair shop (Condition is
virtually new - described as "very good")

You would need to purchase the appropriate Bird Element for the Frequency
and Power of the radios you use.

gb