[BC] "VSWR" Metering

[Alan Alsobrook]

Unfortunately efficiency of the transmitter will remain stable when 
looking into one of these situations. I'm not sure how good the results 
will be if you look at it with a TDR as well. your best results will be 
to sweep the line with an FDR (Frequency Domain Reflectometer) to do 
this properly you would need to sweep the line on commission and on 
regular intervals there after. If you don't have access to one of these 
devices you might want to call someone who does. Even if you don't to 
periodical sweeps (highly recommended) at least if you have a base sweep 
you'll be able to see a problem if it occurs. If you look at Radio Guide 
August issue on page 26 Gary Minker wrote an article about this. (it 
didn't get as technical as I would have liked). I've meet Gary a couple 
of times he's got some really really nice equipment to do extensive and 
detailed sweeping. I have good basic equipment myself. Also to be a good 
sweeper takes some time and practice, so it might be better to have 
someone else come and do it for you. I'm getting pretty good at it but I 
know there is still much I have to learn.

Now to actually answer your question, about the only place you'll for 
sure be able to see a problem like this, in AM you have your line meter 
and hopefully a base current meter if your base current meter indicated 
a drop in power going to the tower while the transmitter is still 
showing full output then you will know of a problem. For FM it gets much 
trickier an indicator may be a loss of coverage, or a fire on the tower.

cld at admin.umass.edu wrote:
> Which brings us to the next question- if indeed you see a "good" reflected 
> power indication at the tx output, but still suspect something is awry, what, 
> in your opinions, are the best places to look (and let's say that you don't 
> have the ability to climb a tower and check the vswr at different points nor 
> have access to a TDR). Efficiency? 

-- 
Alan Alsobrook CSRE AMD CBNT
St. Augustine Fl. 32086 904-829-8885
aalso at Bellsouth.net