HT antenna as a Base??

[KW4EZR]

Dumb question, I have a Diamond RH77C HT antenna, and am pleased with its performance. What if, I used it with a double female BNC barrel and placed it about 40 feet up on a tower? Making sure that the connecters and bottom of the antenna was well weather proofed. Would this make a decent secondary outdoor antenna? I would be using for VHF hi, and UHF 440-470 MHZ. Would this pick up better that it does sitting on top of the scanner, because of the height, worse because of the loss with the connectors and coax, or about the same? Any Ideas? I am not really worried about losing the antenna to mounting; it is so long I only use it at home anyway.

Thanks,

 

[MacombMonitor]

I have read that each coax connector/adapter you introduce, can cause up to a 2.5 dB loss. I don't know how accurate that is, but any amount of loss is bad.

With that antenna, my main concern would be damge to the antenna due to the UV rays of the sun. Outdoor antennas are made of materials that are resistant to UV, I doubt the RH77C is.

 

[KW4EZR]

With that antenna, my main concern would be damge to the antenna due to the UV rays of the sun. Outdoor antennas are made of materials that are resistant to UV, I doubt the RH77C is.

True, I was only thinking about stopping water and not the Sun. Maybe I could climb the tower everyday and put some SPF 30 on it. I was also thinking about an RS 800MHZ HH antenna. I have one EDACS system, and can't pull it in with a scantenna (recently destroyed in a thunderstorm) or a Grove scanner beam II. The RS 800MHZ HH antenna is the only way I can get it.

I was just thinking this would be a quick cheap fix for a second uotdoor antenna.

 

[MacombMonitor]

What type of coax are you using, and how long is the run?

 

[KW4EZR]

I was thinking of using RG-6 the 24GHZ Satillite coax. about a 40 foot run

 

[W4KRR]

It might work, but if you're going to the trouble of putting an antenna on top of a 40 foot tower, why not put up a discone or Scantenna? It will work better than the rubber duck up there.

 

[KW4EZR]

It might work, but if you're going to the trouble of putting an antenna on top of a 40 foot tower, why not put up a discone or Scantenna? It will work better than the rubber duck up there.

I do understand what you are saying. Mainly I was thinking, CHeap, quick, and I already have everything. Don't have the money right now to buy a new base antenna. As far as climbing the tower, and the trouble, that don't bother me. I have a base antenna just thought it might work as a sencond. Really I had only planned to put it to the top of the house and then move it on up after I seen what happened. However, after thinking about the UV rays and the sun rotting the antenna, I might not try it.

 

[Al42]

1. It would work

2. I'd go with LMR400, rather than RG6, for the lower loss.

3. You'll need a counterpoise. 3 rods, aimed about 45 degrees down from the horizontal, at the base of the antenna (connected to the outside [ground] of the BNC adapters) will work - make them about 18" long if you want to pick up VHF-hi (150 MHz) as your lowest band.

4. I'd encase the whole thing (not the radials, but the adapters) in a PVC tube, with end caps (with a "weep hole" in the bottom one) for protection, mainly against UV. The antenna's not really made to withstand weather. PVC pipe is cheap.

 

[KW4EZR]

1. It would work

2. I'd go with LMR400, rather than RG6, for the lower loss.

3. You'll need a counterpoise. 3 rods, aimed about 45 degrees down from the horizontal, at the base of the antenna (connected to the outside [ground] of the BNC adapters) will work - make them about 18" long if you want to pick up VHF-hi (150 MHz) as your lowest band.

4. I'd encase the whole thing (not the radials, but the adapters) in a PVC tube, with end caps (with a "weep hole" in the bottom one) for protection, mainly against UV. The antenna's not really made to withstand weather. PVC pipe is cheap.

Thanks for the help. I might try it. What would you use for the "rods"? Also how did you come up with the length of the rods, If this works I might try one with a RS 800MHZ antenna. Again thank for the help and info.

Darren

 

[radiolalaland]

SPF 30 won't do.

If I'm in the sun prolonged periods of time I use SPF 45 nothing less.

True, I was only thinking about stopping water and not the Sun. Maybe I could climb the tower everyday and put some SPF 30 on it.

 

[kb5udf]

What Rods to use

I've had good luck using the straight part of wire coat hangers
for ground planes. Easy to cut with standard cutting pliers.

 

[Al42]

I might try it. What would you use for the "rods"?

As kb5udf said, wire hangers, but they're brittle enough that I "cut" them by bending them back and forth a few times with pliers. Connecting them to the BNC connectors might be a problem, though - you have to solder them with a torch. Actually, any wire that won't sag from its own weight will do - #12 or 14 copper just bent around the connectors and crimped tight is good. Or you could use a double female connector with a few nuts on it to clamp it to a mounting point, and make sure that the "mounting point" was at least 1/4 wavelength across.

Also how did you come up with the length of the rods

1/4 wavelength at the lowest frequency you want the antenna to work at.