Fiberglass mast poles

[The Howler]

Anybody use these or have recommendations on a quality product?
I’m using 1” galvanized water pipe 28’, for supporting my SPT-500 antenna.
Willing to try something different to quiet down my receive. This was mentioned in a previous post, didn’t want to derail.
Thanks.

 

[M0GVZ]

Wasting your time. RF choke at the antenna feedpoint if you're not using one, make sure you've no common mode RFI. Once that's been sorted then you're at the limits of what you can do as the noise will be what is being generated locally. Could always use a horizontal antenna such as a dipole or yagi for DX which will be quieter but they're no good for local.

 

[bob85]

There is no difference between coax braid and any other conductor connected to an antennas coax/radial junction with regards to noise picked up from local sources like switchmode psu's close to your metal mast and/or ground wires,

if a mast or ground wire presents a low common mode impedance that causes it to carry cmc it will also pick up local generated noise & isolating the antenna from it can reduce that noise significantly,

just isolating the coax with a choke is a half assed job & won't fix noise picked up on a metal mast or ground wire,

a fiberglass fork or spade handle makes an inexpensive isolator for lightweight antennas & saves buying a new mast,

models & words from smart folk & my own experience fixing peoples supposedly unfixable cmc & noise issues prove the above is true.
Any model that does not include ALL conductors is as much use as a chocolate fireguard.

 

[BigLou]

I had a hell of a time with my SWR going up & down useing a fiberglass mast. Had to go to a metal mast and more grounding on radio and amp.

 

[bob85]

That's probably because with the fiberglass pole you only had the coax braid carrying all the common mode current making it sensitive to coax placement, touching the coax, adding a jumper etc,

if grounding causes vswr to change its indicating you have common mode & you should fix that first.

 

[The Howler]

When I get a chance, I will isolate the antenna from the mast as suggested by bob85, then ground the mast separate from everything else.
Sounds like a good plan!
Thanks

 

[bob85]

Howler
If your mast is near to a noise source you think could be causing issues the spt500 having proper radials is a good candidate for isolation & choking the coax.

unlike no radial end fed antennas the spt is pretty good at reducing cmc on mast & coax braid in my experience.

 

[The Howler]

Thanks bob85 for your help.
I have one of the Palomar common noise current choke boxes at my antenna switch, and a 22” coax balun cable that is installed at the antenna feed point. I can unscrew my coax at the radio and hear my noise level drop and see it drop on my meter 1/2 a S unit. So I see room for improvement.
Thanks again for your help.

 

[Marconi]

models & words from smart folk & my own experience fixing peoples supposedly unfixable cmc & noise issues prove the above is true.
Any model that does not include ALL conductors is as much use as a chocolate fireguard.

Hey Bob, I agree, but how many models have you ever seen on the Internet or this forum that included a feed line, and/or any mitigation for CMC for that mater?

In fact, most of the time, the large number of models I've seen don't even include a supporting mast...which you can easily see if the model shows us an antenna image at all.

Modeling a feed line generally can't be easily seen. In some cases it depends on how zoomed-in-on the antenna image is shown. The addition of a feed line in a antenna model is more rare than not too, and yet and still folks tend to believe what they see in images of modeling ideas.

The old saying applies in these cases, "...out of sight out of mind."

With that said however, you are correct to warn of these ill-effects.

 

[bob85]

My way of looking at it is isolate it & you don't have to worry about including it in the model Eddie,
but if you don't & you don't include it in the model,
or don't understand what lengths grounded & ungrounded promote cmc your playing roulette with a blindfold on.