Hi Richard,

Thanks for your quick and extremely thorough and friendly response.
As
no doubt you can tell, I know nothing about antennas. Thanks also for
telling me what each antenna does.

In addition to the messages posted here, I also received a couple of
very helpful private emails.

The image of 1950's domestic engineering sounds like fun, but I think
that in this modern era I can make the necessary adjustments while
talking to my wife by cell phone :-)

I left out some detail in my original message, which I'll now attempt
to rectify. The existing antenna is above my living room, and the
associated TVs are on the far side of the house. In addition, I have
a
satellite dish which is pole-mounted in my yard (my neighborhood has a
lot
of mature trees, so there was no way to mount the dish on the roof),
and its junction point-of-entry into the house is directly on the
opposite side of the house, about 50' as a crow flies or 60' using
cables.
Portions of my house, especially the family room where the HDTV is
located, are pretty hard to wire internally, so I'd like to use this
existing
satellite dish connection and use combiners and splitters as
necessary.

I think that even if I wind up using the rotatable FM antenna, making
an occasional trip to the living room stereo cabinet to rotate the
antenna is an acceptable level of inconvenience.

If necessary I could adopt your suggestion and draw the antenna lines
out of the wall from the exterior. However (in my ignorance) I would
prefer to start fresh and connect "virgin" cables and connectors to
the
antenna, if that's practical. Also, as another poster mentioned, the
HDTV signals are all UHF, and I don't know what (if anything) I need
to
do to provide the appropriately undegraded signal, in a manner which
will 'mix' and 'unmix' well with the dish signal.

Hmm... another option: I have to check this out by going back on the
roof, but I suspect that the lower antenna has a cable, but isn't
actually connected to anything, so perhaps I could draw it outside
without
messing up my FM radio reception. In that case it might just be a
matter
of connecting to an RG6 cable. I could be wrong, but I don't think
that
the existing cable attached to the antenna is coax ... perhaps it's
twinlead. But in any case I now have a general sense of what baluns I
might need to buy, and what I need to look for now to interpret the
existing hardware.

Another remaining concern is how much power I will lose with a 60'
cable run ... it seems that it will be approx. 4 dB which corresponds
to roughly a 60% loss of power, if my math and understanding are
correct. This doesn't even include the existing cable runs from the
satellite dish junction to the TVs. I don't have a good sense as to
whether this is too much power to give up ... perhaps the use of a
pre-amp is justified. I'm also not sure whether I need to provide
power to the pre-amp, and how I might do that. I guess that I can
install a pre-amp sort of "en route" to the far side of the house, in
a location where electrical power is more readily available. A
battery powered pre-amp is also not out of the question, especially if
I don't need to climb onto the roof to change the batteries.

My next step is to visit the roof again in daylight and see what I can
figure out based upon the information that I've received here and in
the private emails. I plan to post back after I've explored this.

Thanks again to you or anyone else for continued advice.

Jonathan

Richard Clark wrote in message . ..
On 24 Dec 2003 09:16:09 -0800, (Jonathan
Epstein) wrote:

Hi,

I'm sorry if I'm in the wrong newsgroup, but you folks seem to know
more about antennas than anyone else on usenet.

The previous owner of my house installed a fairly substantial roof
antenna for radio reception, because his favorite FM radio station was
50 miles away. Here's a pictu
http://epsteinmania.com/jonathan/public/antenna.jpg

I now would like to receive HDTV off-the-air programming at my house.
It turns out that I will need to add about a 60-foot cable run to use
this existing antenna, but it seems that this would be the most
practical method. I'm actually in a pretty good TV reception area ...
when I typed my address into antennaweb.org, it says
that I only need a "small multidirectional antenna":
http://www.antennaweb.org/aw/yellow.asp


So my questions a
1) can I jury-rig this existing antenna for HDTV OTA reception?
AND
2) how do I do it? E.g., to what part of the antenna do I attach an
RG6 cable, and what adapters if any are necessary.

TIA,

Jonathan

Hi Jonathan,

Of the two antennas shown in your first link, it is the upper antenna
that the former occupant used as wideband FM antenna. It is mounted
on the rotator.

The bottom, fixed antenna, is a multichannel medium directional TV
antenna.

Neither is particularly suitable to the HDTV purist, but given that
your needs are so low living in a large signal area, issues of
"purity" may be moot.

It would be simple enough to try one, and then the other. The lower
one may take some time on the roof in participating in the traditions
of 1950's era domestic engineering (twisting the thing until a relay
line of wife and kids affirm the picture is clear now). If you have
only one or several channels located in the same region, the fixed
(non rotatable) antenna will do fine.

Each antenna appears to have its own line, along with a control line
for the rotator. Simply follow those down to where they pass through
a wall into the family room and use them in the same manner as the
previous owner. If you need to lengthen either or both antenna lines
(control line too) there are barrel connectors available at Radio
Shack to mate lengths of line and simple add them a la extension cord
style. The lengthening of the control lines may take more attention,
ask a sales clerk that has at least some time in the saddle at the
store (or try different stores).

If you draw the antenna lines out of the wall and make the extensions
outside, tighten the connections firmly and wrap all metal bright work
with electrical tape in overlapping turns (about a foot or more of
tape for three inches of bright work). Start the tape with a margin
before and after the bright work, on the plastic of the actual cable,
so no rain penetrates through the back of the connectors. If the
connectors are hooded, start on the cable behind the hood and progress
to beyond the hood of the mated connector.

73's
Richard Clark, KB7QHC