Whip antenna whistle fix?

[amoking]

I have two 50" whips on the roof of the truck (Larsen NMO150B [2m rx/tx] and a Larsen NMO40B for scanner). They whistle like mad but I understand the reason behind it. I know about the twine and heat shrink cure which I may try. Anybody care to opine on whether a light spray glue tack will help to hold the rope in place before I set the heatshrink? I would guess that it would not materially affect the performance of the whip.

mmckenna?

 

[mmckenna]

Shouldn't hurt anything.

I know the issue you are talking about. I found that it was much more noticeable when the humidity goes up, like when the fog rolls in out here on the coast.
I switched to 1/4 wave VHF antennas and that brought the noise level down a lot, but that's not going to help you on the low band side.

Let us know how it works.

 

[amoking]

Shouldn't hurt anything.

I know the issue you are talking about. I found that it was much more noticeable when the humidity goes up, like when the fog rolls in out here on the coast.
I switched to 1/4 wave VHF antennas and that brought the noise level down a lot, but that's not going to help you on the low band side.

Let us know how it works.

They were howling yesterday from Contra Costa County to Riverside County and back. I don't mind it but the wife hates the noise....and the antennas themselves.

 

[mmckenna]

They were howling yesterday from Contra Costa County to Riverside County and back. I don't mind it but the wife hates the noise....and the antennas themselves.

I too tend to get annoying noises coming from the general area of the passenger seat. I found it tends to go away when I travel alone.

Keeping the antennas clean seems to help a bit. I've found that wiping them off frequently helps lower noise, but won't eliminate it. It's not just bug parts, but a general collection of dust builds up on the forward facing edge.

I used to spend a lot of weekends on a lake in the Sierra foothills. Coming back home I'd hit the summit and drop back down towards the ocean and the antenna would start singing to me. Even a 1/4 wave VHF whip will do it.

 

[prcguy]

Turn your stereo up louder.

 

[spacellamaman]

throw one of these on your roof

with the proper alignment, you'll derive these benefits:

1. at around 60mph you'll no longer hear those 50" whips

2. at around 70mph you won't hear your stereo either

3. after driving for around 30 minutes or more at 70mph, you'll be able to go to sleep that night without having to hear your partner droning on about whatever...

unfortunately no speed or duration will prevent you from feeling her punching you in the kidney when she doesn't hear you say "yes dear"

 

[WB9YBM]

Well, if the antenna whistles, your engine and tires each humming--sounds like the start of an interesting orchestra. Add some rattle from a trailer and you're half way to the next top 40 hit...

 

[spacellamaman]

Well, if the antenna whistles, your engine and tires each humming--sounds like the start of an interesting orchestra. Add some rattle from a trailer and you're half way to the next top 40 hit...

true that, frankly my car already sounds like a half-drunk high-school-band drum-section, but you add in that particular antenna and you have not just the orchestra, but the fat lady singing, busting all the wine glasses within a 100 meter radius.

 

[RFI-EMI-GUY]

I had an old 99 Plymouth Voyager minivan that had a spiral around the OEM AM/FM whip antenna to reduce wind noise and drag. Unfortunately the car wash rollers got a good grip on it.

You could epoxy some mono-filament line in a spiral along the whip. Be ready to adjust the VSWR and shorten the antenna as It may affect the tuning with dialectric loading.

 

[amoking]

I had an old 99 Plymouth Voyager minivan that had a spiral around the OEM AM/FM whip antenna to reduce wind noise and drag. Unfortunately the car wash rollers got a good grip on it.

You could epoxy some mono-filament line in a spiral along the whip. Be ready to adjust the VSWR and shorten the antenna as It may affect the tuning with dialectric loading.

That's why using twine is favorable I'm told. SWR etc is supposedly unaffected but wind noise is.

 

[RFI-EMI-GUY]

That's why using twine is favorable I'm told. SWR etc is supposedly unaffected but wind noise is.

Nylon twine? Hemp would get wet. Wet Hemp is well, a crime.

 

[amoking]

Nylon twine? Hemp would get wet. Wet Hemp is well, a crime.

Yes. Spiral from top to bottom then cover with heat shrink.

 

[RFI-EMI-GUY]

sounds like it would work, but the drag?

 

[bharvey2]

While I usually rely on prcguy's solution, you might try heavy fishing line or "weed wacker" line for the spiral wrap before applying head shrink. Those shouldn't absorb water.

 

[amoking]

While I usually rely on prcguy's solution, you might try heavy fishing line or "weed wacker" line for the spiral wrap before applying head shrink. Those shouldn't absorb water.

Good point. I figured nylon cord and a tight heat shrink should do the trick but fishing line might be a sound idea. In eyeballing it, it seems that 1 strand paracord (1/16") is the right size.

 

[amoking]

Well, it went perfectly. No issues with SWR or reception and the whistling is gone. I spray tacked the masts then wrapped in M90 cord at a rate of about 1 turn per 2" or so. It was not precise. Then I slid over 3/16" shrink tube to lock it all down. Bingo. Masts seem to flex slightly less at speed also.

 

[bharvey2]

Well, it went perfectly. No issues with SWR or reception and the whistling is gone. I spray tacked the masts then wrapped in M90 cord at a rate of about 1 turn per 2" or so. It was not precise. Then I slid over 3/16" shrink tube to lock it all down. Bingo. Masts seem to flex slightly less at speed also.

Glad it worked for you. Funny thing is, as I've gotten older, my hearing has gone down the tubes. The worse part is, certain sounds/frequencies really "stand out from the crowd" and drive me nuts. Finding a solution to them works wonders for your mental state. BTW, how do you know the antenna flexes less at speed? I'm envisioning you hanging on to the roof, watching your antenna while the Mrs. is driving on the highway. I'm in the East Bay so I just might see that or at least hear of it on the news.

 

[amoking]

Glad it worked for you. Funny thing is, as I've gotten older, my hearing has gone down the tubes. The worse part is, certain sounds/frequencies really "stand out from the crowd" and drive me nuts. Finding a solution to them works wonders for your mental state. BTW, how do you know the antenna flexes less at speed? I'm envisioning you hanging on to the roof, watching your antenna while the Mrs. is driving on the highway. I'm in the East Bay so I just might see that or at least hear of it on the news.

I have a dual sunroof on my cab so I can look up and see them.