Any idea what brand this is?

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jon_k

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I just purchased this off eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=310062483557&ssPageName=STRK:MEWN:IT&ih=021

It was cheap and small. I'll be putting this on my truck in the back near the tailgate.

The purpose of this will be for APRS service on amateur radio. For those unaware, it transmits your GPS coordinates over the air (to see an example tune in to 144.39 in your area and maybe you will hear some APRS activity.) As such, max distance isn't a concern here. 10-15 miles will be plenty to hit several APRS internet gateways to get my position on the internet. With a minutely transmission plenty of packets should get through. If it DOES turn out to be a dummy load, I'm sure it'll work just well enough for the duty I'll be giving it.

I just couldn't justify a large good quality 2m antenna for a .5 second data packet sent every minute.

I also ordered an SWR meter, so the suitability of the antenna should be obvious once tested.
 
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jon_k

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It's a Tram.

Second antenna on the top row of this page ---> http://cqdxelectronics.com/cqdx/Dual_Band__And_Glass_Mount_Ante.html

Nice and stealthy if hole mounted. If it does decent on 800, it'd be a good scanner antenna. Probably do fine on 2m and 70cm though.
Your experience with antennas has won out again. Thanks for finding this information. I cannot find any reviews for this antenna though other Tram antenna reviews are positive.

Not much else will matter as long as I can get a lowish SWR for ERP efficiency.

50 watts output will probably be overkill for the application. The furthest APRS node that can upload my transmissions to the internet is an area halfway between downtown Dallas and DFW airport. At that point, the closest internet node is 7 and 10 miles in either direction respectivly. I'm not sure if at 50 watts this antenna will reach that far, but it should only be a minor dead spot in coverage.

The most APRS activity oddly enough seems to be in the north greater Fort Worth area which is where I live, so this should work extremely well around my town.

I very well may post SWR and FM voice review here so others can contact this seller if interested.
 
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jon_k

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UPDATE ON PERFORMANCE

I said I would report back with an update on performance for those interested.

Tested SWR on 144.39mhz at various power levels and here are the results.

5w SWR = 1.2 to 1
25w SWR = 1.5 to 1
50w SWR = 1.8 to 1

144.39 was chosen as it is the national APRS frequency which this will be intended to transmit on.

The eBay seller claimed this is his "house brand" and they are sold nowhere else, which gave me worries. Could be a powder coated clothes hangar -- but it seems sturdy and the package says AntennaMax(TM) he may be correct as I cannot find a page anywhere else on the net with that brand name.

Definitely a sturdy design and the SWR is wonderful and safely within APRS uses. I should never have to go the full 50 watts.

Here is the seller:http://myworld.ebay.com/antenna_2-way_direct/
 
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ka5lqj

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Hmmm...

Hi Jon, All,

I had a 5/8ths mobile antenna like this, less the "curley-Q" in the middle, some years ago. It was
made by PRO/AM. Infortunately, when I sold the van it was under, I forgot to remove it. :-(

It worked real well with the Heathkit 2036 and 10 watts.

Respectfully,
73,

Don/KA5LQJ

Em-32
 

jon_k

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Hi Jon, All,

I had a 5/8ths mobile antenna like this, less the "curley-Q" in the middle, some years ago. It was
made by PRO/AM. Infortunately, when I sold the van it was under, I forgot to remove it. :-(

Donald, this is an interesting comment "the van it was under". Are you telling me you mounted the antenna under the vehicle sideways for APRS operation? I never thought of this. On second thought this sounds like an excellent way to keep the installation stealth. One of my reasons for APRS is for a poor-mans LO-JACK system. How well did it work at 10 watts horizontal orientation?


In fact, I already had plans to paint the GPS receiver puck thingy black. Right now it says BYONICS GPS in white text. It wouldn't be so bad if like the image above, it omitted GPS.

I plan to paint it black and use stencil to write CELL BOOST PRO or the XM RADIO logo on it. That will make thieves think it's something that is totally harmless that can be removed after they reach their chop-shop destination. Giving ample time for APRS packets to tell me where they're at.

I can see a possibility of petty thieves who want to steal stuff yanking it when it says XM RADIO in the parking lot. Along with all my HAM gear and amplifier, subwoofer, and stereo. Thing is, the pro's won't remove that stuff until after they get to the chop shop. I hope I never have to use it -- but I'd like to boost my chances if it happens to finding them or at least recovering the vehicle.

My APRS setup will be quite nice when finished and I'll probably make a thread with pics on these forums.
 
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UPDATE ON PERFORMANCE


The eBay seller claimed this is his "house brand" and they are sold nowhere else, which gave me worries. Could be a powder coated clothes hangar -- but it seems sturdy and the package says AntennaMax(TM) he may be correct as I cannot find a page anywhere else on the net with that brand name.
would powder coated antennas have the black come off if it gets wet? My antenna from that place was in the trunk and the trunk leaked water in somehow and it was wet and had black paint or coating come of from the chairs sitting on top of it and when i picked it up i could scratch the black off with my finger nails real easy as if it was soaked in paint remover.

Eric burris
 

AK9R

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would powder coated antennas have the black come off if it gets wet?
No. Powder coating is a heat-activated plastic powder that is dusted on an object dry and then the object is put in an oven to activate the chemicals and bake the finish onto the object. Done properly, it makes for a very tough coating. If the black finish came off of your antenna when it got wet, then it sounds like a cheap finish.
 

hoser147

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No. Powder coating is a heat-activated plastic powder that is dusted on an object dry and then the object is put in an oven to activate the chemicals and bake the finish onto the object. Done properly, it makes for a very tough coating. If the black finish came off of your antenna when it got wet, then it sounds like a cheap finish.
Thats right its very durable, we have a plant here that makes alum. wheels and they use a powder type finish on them for Honda and it it very durable. Hoser
 
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