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October 19, 2019, 09:49:00 PM
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CAP Talk  |  Operations  |  Tools of the trade  |  Topic: Portable tripod-mounted antenna recommendations, coax
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Author Topic: Portable tripod-mounted antenna recommendations, coax  (Read 877 times)
xyzzy
Member

Posts: 71

« on: September 11, 2019, 06:26:50 PM »

I have been tasked to participate in an exercise in late October as a ham operator. I don't know if CAP will be part of the exercise; details are on a need-to-know basis so I can't look it up. I need to complete my personal portable equipment with a portable 2 m / 70 cm antenna, and coax with UHF connectors to go from the antenna (outdoors) to the radio (in a town office or similar facility, details unknown).

My plan is to obtain a 5 foot antenna mast, support it with a surveyor's tripod which I have, and clamp the antenna to it. I'm keeping it short to minimize the chance of it getting knocked over.

Naturally I would like it to work with CAP frequencies in the vicinity of 2 m for future operations. I have some LMR 400, but the stiffness is unpleasant to work with and might create a tripping hazard. I'm looking for suggestions.
« Last Edit: September 11, 2019, 06:30:19 PM by xyzzy » Report to moderator   Logged
arajca
Salty & Seasoned Contributor

Posts: 4,416

« Reply #1 on: September 11, 2019, 06:55:20 PM »

I've used RG-8x for coax.

For a mast, I use five 4-foot camo net poles (fiberglass HD) and a tripod adapter (three poles for legs, two for mast). I clamp a  mobile-base antenna ground plane adapter to it and use a broadband VHF antenna, same model CAP uses on vehicles (19" tall).
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NovemberWhiskey
Member

Posts: 77
Unit: NER-NY-301

« Reply #2 on: September 11, 2019, 09:34:24 PM »

I would not recommend RG-8X for configurations that might see use at 70cm frequencies; you're apt to lose almost 10dB in a 100' feed line. If LMR-400 is too stiff, Times Microwave does also make a stranded-core version with similar characteristics (LMR-400UF I think) and the usual suspects make a clone product. LMR-240 is another possibility, particularly for shorter runs.

I have the aluminum camouflage poles for a mast and guy them to ground stakes with fluoro green/yellow paracord; it's topped with a PulseLarsen NMOWB150B (cut for lowest SWR across the CAP frequencies) on a ground-plane kit; I use LMR-400UF for the feed line. That particular antenna won't help you much on 70cm obviously.


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Bullpup95
Recruit

Posts: 5
Unit: SER-MS-051

« Reply #3 on: September 12, 2019, 11:12:18 PM »

Can I suggest a N9TAX roll-up j-pole dual vhf/uhf antenna.  They are excellent and work great on CAP and most out of band 2m frequencies used within SAR with minimal deviations on the SWR.  Can be pulled up into a tree with a small line or attached to your portable antenna mast.  I believe he is selling mostly through e-bay now. 
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Adam B
Member

Posts: 65

« Reply #4 on: September 25, 2019, 12:49:09 PM »

I'll second the roll-up J-pole. Make a mast of segmented PVC, then hang the j-pole form the top.
You can make one yourself or buy on on Ebay. Light weight and effective.
Dipoles are also quite easy to build yourself in the 2m range. I use a vertical 2m half-wave dipole at my QTH.

As you may know, if you intend to use your radio on CAP frequencies, it does need to be NTIA compliant and CAP approved. There is a list approved radios on the CAP communications page. Baofeng, Anytone, etc, are not on the list.   


...That all said, I'm a little concerned about any need-to-know, super-secret, amatuer radio operations. Ham radio is, by tradition and regulation, a very open, in-the-clear radio service. So-and-so said it was okay isn't a defense, responsibility is with the operator.

Make sure you're not getting yourself into anything that might jeopardize your license.
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Adam
Eclipse
Too Much Free Time With Silver Clasp
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Posts: 30,282

« Reply #5 on: September 25, 2019, 04:18:39 PM »

I have been tasked to participate in an exercise in late October as a ham operator. I don't know if CAP will be part of the exercise; details are on a need-to-know basis so I can't look it up.

If you're going to be there in your capacity as a ham or a CAP member, it's not a secret, and there should be plenty of information
available.  For starters, ask the person who tasked you - since they tasked you, you "need to know".

With that said, I had good experience in the past with portable light stand tripods. 
They tend to be robust and fold up nicely.  Lots to choose from on the Mothership.



« Last Edit: September 25, 2019, 05:29:44 PM by Eclipse » Report to moderator   Logged


PHall
Salty & Seasoned Contributor

Posts: 6,687

« Reply #6 on: September 25, 2019, 05:20:18 PM »

Speaker stands work pretty good too. They're designed to be stable even with a 30 pound speaker up on top.
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xyzzy
Member

Posts: 71

« Reply #7 on: September 25, 2019, 08:59:35 PM »


As you may know, if you intend to use your radio on CAP frequencies, it does need to be NTIA compliant and CAP approved. There is a list approved radios on the CAP communications page. Baofeng, Anytone, etc, are not on the list.   


...That all said, I'm a little concerned about any need-to-know, super-secret, amatuer radio operations. Ham radio is, by tradition and regulation, a very open, in-the-clear radio service. So-and-so said it was okay isn't a defense, responsibility is with the operator.

Make sure you're not getting yourself into anything that might jeopardize your license.

At this point, when operation on CAP frequencies is appropriate, we have a sufficient number of CAP-issued radios to use them. At this time I have not been informed of any CAP participation in the exercise.

Exercise details are only confidential until the scenarios are revealed as they unfold. Once the exercise controllers reveal details to the exercise participants they will no longer be confidential.
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CAP Talk  |  Operations  |  Tools of the trade  |  Topic: Portable tripod-mounted antenna recommendations, coax
 


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