FM Antenna

[Bob Simon]

I live in a 2-floor house and had FM reception problems using twin lead dipole antennas. Around 10 years ago, I purchased a 2-element, omni antenna (looks like this: http://www.radioshack.com/product/index.jsp?productId=3740648) and mounted it in the attic at the peak of the roof. I connected itto a 75 Ohm transformer and a 2-way splitter and ran RG-59/U to receivers in the upstairs bedroom and office.

This worked well but it was too difficult to bring the coax downstairs to my living room without going outside so I bought a Terk Pi amplified antennafor my NAD receiver there. That usually gives acceptable results but for some stations the gain or orientation of the Terk Pi must be adjusted, which is inconvenient because it's up on top of the entertainment center cabinet. Now that we're doing some home renovations, a few walls and part of theceiling are open so this is the perfect time to run coax from the attic tothe living room.

1. Do I need to boost the signal at the antenna for a 3-way split? If so, how much gain do I need? Is 8 dB enough?

2. I still have RG-59/U on hand. Is this ok for the new 65' run to the living room or should I use RG-6 instead?

3. If RG-6 is recommended for the new run, should I replace the existing 25' runs of RG-59/U while I'm at it?

4. What about the connectors? I originally used crimp-ons. Should I cut them off and have someone install good compression fittings like the kind technicians now use for cable and satellite TV?

5. Does anything in this antenna system need to be grounded? I see the splitter has a bolt for a ground wire.

 

[William Sommerwerck]

At the risk of seeming a shill for Magnum Dynalab, you should get their MD
205 "signal sleuth".

http://www.magnumdynalab.com/md205.htm

It doesn't just boost the signal. It cleans it up. Remember to put ferrite
chokes on the AC power cords of all your FM equipment (and possibly the
audio cables), so the good work done by the MD 205 won't be undone by direct
RF entry.

 

[William Sommerwerck]

It doesn't just boost the signal. It cleans it up.

Not really, but it seems like it would help get rid of overload from
excessively strong nearby TV signals. Just an FM band pass filter
would probably do most of the heavy lifting.

I guess it depends on how you define "clean up" -- but it definitely audibly
improves some signals. And this improvement varies with the setting of the
preselector control.

Obviously -- your mileage may vary. I wouldn't recommend the product if it
didn't work for me.

That does no good with todays plastic case, unshielded receivers. Some
work better with no antenna attached. The FCC Part 15 conducted
radiation filter found the AC power cable usually does a great job of
blocking such RF pickup.

Not on the metal-cabineted products I own.

I've never heard of such a filter. That doesn't mean it doesn't exist, but
I've never heard of it.

Without a line choke on the tuner, the MD 205 simply doesn't work properly.

 

[J.B. Wood]

"signal amplification variable from -10dB thru +30dB (30 times
to gain) to bring weak stations to full quieting* and tame
strong, harsh, local signals"
30dB power gain is 1000 times.

Another "Dilbert" moment - failure to communicate between sales and
engineering departments. (I'm being kind here in this assessment.)
Sincerely,

 

[Allodoxaphobia]

Another "Dilbert" moment - failure to communicate between sales and
engineering departments. (I'm being kind here in this assessment.)
Sincerely,

They do it with oxygen-free copper.

Jonesy

 

[Bob Simon]

RG-59/u is usually garbage. Good enough for indoor patch cable use,
but not much else. I strongly suggest RG-6/u with waterproof
compression (not crimp) connectors. (snip)
Note that there are different types of RG-6/u which require slightly
different compression connectors. A connector made for RG-59/u will
not work with RG-6/u.

Yesterday, the electrician replaced my old run of RG-59 with RG-6 cable. The box is labeled: CB1B06DSCR0-05. I didn't realize that my other existingrun is already RG-6. The cable is marked with "E83032 F6SSVV". Can all types of RG-6 cable use the same compression connectors? If not, is it sufficient to determine if the outside diameter of the cable is the same?
Bob Simon

 

[Bob Simon]

The electrician had to work another job this morning so the contractor brought over his connectors and tools. (The box of cable was already here.) The new 65' run from the antenna in the attic allows my receiver to play even marginal stations without pressing the mono button so I'm happy to reportthat this was a complete success. No need for an amp at the antenna.

Since I've never pressed on a compression connector before, I'd like to know if I'm doing this optimally. First, I adjusted the stripper to leave allthe braided shield on the inside cut while going almost all the way to thecore for the outside cut. Then I folded the braid back over the jacket while leaving the foil covering the insulator and pushed on the connector until the foam was even with the inside of the connector. Finally, I insertedthe core and connector into the handle of the tool, made sure it was aligned, and squeezed.

For the quad-shield RG-6, I left only the inside foil on the foam and folded the rest over the jacket. It was a lot harder to push the connector on the cable so I used a twisting motion.

 

[Bob Simon]

- You do NOT want to peel the foil off the dielectric.
- You do want to wrap the wire braid back over the outer jacket.

Those were the two main points I was not sure of. Thanks very much for all the help and advice.
Bob