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Tram 1486 for GMRS use and tuning of it


WRWR489

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I bought this base antenna because of the reviews. Does anybody use one and if so how does it perform. This will be on my wouxon 100G. I have read do not cut the lower elements and yet the instructions call for cutting all 3. Any advice? TIA.

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I have a 1486 that I have used with my KG1000G, my XTL5000, my repeater made of two KG1000Gs and my VXR7000 repeater.  it works very well - on simplex i'm getting 40+ miles with it.

Per the instructions I cut all 3 elements, and IIRC, the SWR was about 1.01:1 .  Ignore anyone that tells you to not follow the manufacture's instructions how how/what to cut.

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  • 4 weeks later...
11 minutes ago, WRUT935 said:

Has anyone compared this to the Ed Fong GMRS Jpole in PVC. Specifically, will this be an upgrade over the Ed Fong antenna?

Compare the specs:

Tram 6.5 dBd, which is ≈8.6 dBi

Fong 2.2 dBi - it has about the same gain as a dipole  

Tram is fiberglass encased  

Fong is contained within PVC

On paper the Tram looks better. 

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On 5/3/2023 at 9:43 PM, WRUT935 said:

Has anyone compared this to the Ed Fong GMRS Jpole in PVC. Specifically, will this be an upgrade over the Ed Fong antenna?

This is solely my experience and not a scientific comparison.  I had Ed Fong's DBJ-UHF antenna mounted on the rooftop for a few short months.  It worked reasonably well and had an acceptable SWR for my purposes, though I don't have the SWR number recorded.

Unfortunately, I went up on the rooftop to check the mount on a clear day after a period of harsh winter weather, and gave the mount a slight twist to assure myself that the PVC was still nice and tight.  When I went back to the radio, there was no reception and a check of the SWR showed it to be extremely high.  When I tweaked the antenna, I  broke the solder connection in the base, which is my fault and not necessarily a strike against Fong's antenna.

I replaced it with a Tram 1486, which cost more, but is also more robust.  I was able to trim the Tram to an SWR of 1.01:1 with the unit mounted on the roof, and I don't feel the need to go check it to see if the PVC is still secure in the end caps. 

Reception is very good with the Tram, though I don't have the instrumentation to accurately compare it to reception with the Ed Fong.  My signal reports seem to be better with the Tram, though that is subjective as well.

Ultimately, I was fine with the Ed Fong, and I am probably a little happier with the Tram 1486, mostly due to it's robust construction.

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6 hours ago, WRUT935 said:

@Steveshannon - Dr Fong's site advertises 5 dB for his GMRS antenna, does that translate to 7.15 dBi?  

I'm not familiar with his GMRS antenna, but I assume it's like his other antennas. I would note that he doesn't specify gain in one of the usual frames of reference: dBi or dBd.  Instead he says:

Gain:  5 dB over reference ground plane

Without knowing what gain the "reference ground plane" has with respect to either an isotropic antenna or dipole antenna, that's meaningless.

Look closer at the DBJ-2, of which the commercial model covers the same frequency range.  Here's what he says: 2.1 dBi, which is exactly the same as a dipole. In other words it has 2.1 dB gain over an isotropic antenna, which is a theoretical antenna that has no gain. That's what the 'i' stands for in dBi.  It's just a reference.  Another reference is dBd, which means referenced to a dipole. 

A dipole has 2.1 dB gain compared to an isotropic antenna, all other things being equal.

A yagi might have 9 dB gain compared to isotropic (9 dBi) or 6.85 dB compared to a dipole (6.85 dBd).

Then he goes on to say that's 6 dB gain over a 2 meter J-pole used at 450 MHz, that's impressive, right, but it simply means that it doesn't lose as much power as the J-pole used at a frequency it's not intended for:

image.thumb.png.5443cb926c5e32627b21205baa4146e1.png

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