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Portable repeater


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I have a portable repeater all racked up & ready to go.

 

Any suggestions for the antenna?

 

Chris

 

You really need to give us a better idea of what you have and how you intend to use it. The antenna itself may not be as critical as how you plan to erect it when you set up. My radio club has a rollup J-pole that they fasten to a 15' extendable post and bungee to one leg of their shelter. It works great, but may not be so useful to others. More info from you means better suggestions from us.

 

And what's your budget?

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I have a Icom 45w repeater. Occasionally I will use it for various public events coordination.

 

There will be a few handheld radios out in the field all within 1 mile or less of the repeater.

 

In terms of the antenna...........budget isn't so much of an issue. Something simple to deploy that isn't massive would be ideal. Something that would mount to a tripod & mast would be great.

 

Chris

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I have a Icom 45w repeater. Occasionally I will use it for various public events coordination.

 

There will be a few handheld radios out in the field all within 1 mile or less of the repeater.

 

In terms of the antenna...........budget isn't so much of an issue. Something simple to deploy that isn't massive would be ideal. Something that would mount to a tripod & mast would be great.

 

Chris

 

You can pick up an Ed Fong J-Pole kit off Ebay for around $25. You'll need to purchase a piece of pvc pipe locally. Instructions come with the antenna. As for a mast, something like this might be good for you: http://www.ebay.com/itm/13-Foot-Telescoping-Mast-Tripod-For-Portable-Antennas-Elevated-Cameras-WiFi-/191937470658

 

I did a search on ebay using mast tripod as key words. There were several other good possibilities in the search results.

 

The antenna that Pastor Gary mentioned would work just as well. Really, most any small base station antenna for your frequency range will work fine. The heavier ones will need a sturdier mast and tripod.

 

For your purposes, you're only limited by your ingenuity and imagination. There are lots of good solutions. I suggest you look at some of the setups that hams use for go kits. They're easily found on the web at various amateur radio websites.

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I have to second the Ed Fong j-pole. The thing is, if you buy it off e-bay from Ed, give him your transmit frequency, he will tune the thing for that frequency!  

 

Or you can try and build it yourself.  Either way, I use the Ed Fong with a portable GMRS repeater as well as on a semi permanent basis (Military move every three years).  When I use it with the portable repeater (about 15' of pole with the antenna on top) I get a good 2 mile range out of it with mobiles, and a solid mile + on HT's.  

 

The atenna is light enough that I literally strap my 15' of shelter poles to a corner of my 10'x10' straight leg pop up.  It's a little tricky to get the antenna mounted to an upright pole, but with a little fiddling it's not so bad.  I use a PVC "T" cut in half, four hose clamps, and about 3" of the left over PVC pipe from the antenna build. You make something that looks like an "H" clamping one side to the poles, and the other to the antenna. Works like a charm.

 

Hope this helps!

 

James

WQUL457

W8JVF

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Thanks for all the info.

 

What are you all using for coax from the antenna to repeater in these portable/temporary situations?

 

I'm using 1/2" superflex heliax @ home, but would prefer something more flexible for use in the field.

 

My ham club uses about 15' of RG-58 for their field setup on 2M and 70CM. Works fine. Just for comparison's sake, typical mobile radio installs use RG-58 and the usual length supplied with the mount is about 17'.

 

If your total coax run is about 30', you would do fine with RG-8.

 

In all cases, the less adapters in the line, the better.

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I have some items useful for portable deployment, My favorite is the park on monopole base. small and simple to use with a short section of mast. secured with the weight of your car or truck. can accommodate telescoping mast and keep your cable run short so you could use smaller cable like 195 or 240. 

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The problem with any cable that uses 'foil' as the inner shield is that over time it will begin interacting with the braided wire shield and become 'noisy'. This doesn't happen immediately and may take many months to develop, but it isn't a question of "if" as much as a question of "when..." : wacko.png

 

For detailed information, see here: http://www.repeater-builder.com/antenna/double-shielded-coax.html

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How big of a mast are you looking to use ? Our SAR team purchased the mast here on ebay - http://www.ebay.com/itm/ANTENNA-TRIPOD-29FT-ALUMINUM-PORTABLE-TOWER-MAST-KIT-NEW/361384099911?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D20131227121020%26meid%3Dc8638571b9a64db4b78809ad1b1b3bc3%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D360908000786

 

It works awesome and is light enough to carry up a trail. As for cable I tried various options from RG213 to 1/2" superflex. When all said and done we had the best luck with RG142. The loss for 30' is not enough difference than the 1/4" superflex hard line and holds up much better. I liked the 1/2" and 1/4" hard line but after both were kinked in half on the first deployment i knew they wouldn't work.

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How big of a mast are you looking to use ? Our SAR team purchased the mast here on ebay - http://www.ebay.com/itm/ANTENNA-TRIPOD-29FT-ALUMINUM-PORTABLE-TOWER-MAST-KIT-NEW/361384099911?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D20131227121020%26meid%3Dc8638571b9a64db4b78809ad1b1b3bc3%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D360908000786

 

It works awesome and is light enough to carry up a trail. As for cable I tried various options from RG213 to 1/2" superflex. When all said and done we had the best luck with RG142. The loss for 30' is not enough difference than the 1/4" superflex hard line and holds up much better. I liked the 1/2" and 1/4" hard line but after both were kinked in half on the first deployment i knew they wouldn't work.

 

Dang.. I'll have to take a look into that.. 

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Its a really slick mast kit. Sometime we only use a few poles and other times use all of them. For a fast deployment with not all the poles we don't even run guy ropes out and it works fine. We have a small VHF dipole antenna that is pretty light so it rarely moves the mast. 

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I have found that a No-Ground plane mobile antenna on a good magnet mount works great for a portable repeater. I have also used the No-Ground plane mobile antenna on a base antenna kit with radials and used it on antenna mast. The important thing to watch out for is to make sure that your antenna cable center conductor and shield are made of the same materials. 

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The problem with any cable that uses 'foil' as the inner shield is that over time it will begin interacting with the braided wire shield and become 'noisy'. This doesn't happen immediately and may take many months to develop, but it isn't a question of "if" as much as a question of "when..." : wacko.png

 

For detailed information, see here: http://www.repeater-builder.com/antenna/double-shielded-coax.html

This. I've been forced to install some low tier repeater setups using LMR400. I've always noted that it should've been a different type of coax so when it does have to be replaced in a few years it'll be documented that a senior systems tech stated that. Part of sales persons selling an not consulting the guys who actually have technical knowledge.

 

Sent from my SM-T350 using Tapatalk

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