"R.Smyth" wrote in message
...

"Charlie Bress" wrote in message
...
"R.Smyth" wrote in message
...
I have a TV antenna as a back up to my dish.
I believe the head end unit of the antenna amplifier is defective. It
is
on
the antenna.The twin lead from the antenna connection goes in one end
and
the coax goes on the other. The coax then goes to a plug in unit in
the
house which is connected to the TV.
Is this unit on the antenna a special device or is it nothing more
than
a
standard converter from 250 ohm twin lead to 75 ohm coax?
If so, that will save me buying a whole new amplifier.
Thanks
DS


=^..^=

What makes you think it is defective? What is the " plug in unit in the
house"? It has to have some sort of identification.

It could be an amplifier up there with a power supply down below or the
unit
below might be the amp and the part on the antenna is just a 300 ohm
twin
lead to 75 ohm cable transformer. But if your signal has deteriorated
and
you have an amplifier you really have to find out where it is. The
transformers themselves rarely go bad, but the connections out in the
weather may have corroded. Tell us what you have.

Charlie

The unit on the antenna is just a small box, about the size of a small
candy bar. There is no power going to it. The only wires are the twin
lead
at one end and the coax at the other. (If it's an amplifier, it would need
a
power lead, no?) The other unit is a box , maybe a little bigger than a
cigarette box, which plugs into the wall in the house. The coax from the
antenna goes on one connection and a coax cord to the TV set goes on the
other. There is a gain control on it and an FM signal trap. This would
seem
to be the actual amplifier. It's a Radio Shack product.
I believe the top unit is defective because I may have broken something
in
getting the old coax connector loose. I'm just wondering what will happen
if
I merely replace the top unit with a 250 to 75 ohm transformer.
Thanks.
ds

First, it does seem that the unit on the antenna is only a twin lead to coax
transformer and the amplifier is down near the tv. If you think you broke
something at the transformer while getting the coax connector loose then it
is very likely that what broke is the short piece of the inner conductor of
the cable. If this is true, you would be well advised to replace the cable
with a preassembled cable that has the connectors already in place. It is
possible to just cut the cable and attach a new connector. But given your
inexperience with this sort of stuff it is unlikely that you can accomplish
this so that you have a weatherproof connection. It is one thing to hack
together a fitting to use inside the house, but making a weather resistant
connection is not as forgiving. If the cable that you have is a commercially
assembled one you could just reverse it and put the end that had been in the
house in the air and then put a new connector on the end that is now
indoors. Or as someone else has suggested replace both the transformer and
the cable. It won't hurt anything and will likely help.

Charlie