Tram 1486 for GMRS use and tuning of it

[WRWR489]

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.

[OffRoaderX]

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.

[WRWR489]

Thank you. One more question, do I need to compensate for the insertion part of it or just cut to the specified length?

[OffRoaderX]

I just did what the words on the direction-sheet said to do - dont over think it.

[WRUT935]

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

[SteveShannon]

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. 

[Sab02r]

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.

[WRUT935]

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

[BoxCar]

5 minutes ago, WRUT935 said:

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

Yes. 2.1 dBi is  unity or 1dBd.

[SteveShannon]

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:

[SUFFO]

I am extremely new to this I bought this antenna the tram 1486 I want to cut it for GMRS, I have stared at the cutting chart over and over again, but I’m still not quite understanding. I want to use the antenna for GMRS, and the repeaters. The frequencies are 462 to 467. I understand how to cut it and how to measure, but I’m not sure what line on the cut sheet I need to go by can anybody help? when looking at the cutting chart for frequency 462 and you follow it across it says 447.6–471.5  my question is, is that the line I need to use when cutting. 

[Guest]

why not just get a better, cheaper pre tuned antenna meant for GMRS?  

[WRPG745]

1 hour ago, WSAL482 said:

I am extremely new to this I bought this antenna the tram 1486 I want to cut it for GMRS, I have stared at the cutting chart over and over again, but I’m still not quite understanding. I want to use the antenna for GMRS, and the repeaters. The frequencies are 462 to 467. I understand how to cut it and how to measure, but I’m not sure what line on the cut sheet I need to go by can anybody help? when looking at the cutting chart for frequency 462 and you follow it across it says 447.6–471.5  my question is, is that the line I need to use when cutting. 

HI I don't know that antenna, but I did see this link:

https://pascogmrs.us/tram-1486/

looks like a complete writeup (and a decent antenna)

-jc

[SUFFO]

thanks I’ll check it out. I wound up tuning it and it came out SWR 1.2 I put it on a stand outside my house just to try it out and apparently it works. Great people are now hearing me and I was only using a GMRS Pro HT.

[COBrien]

Have you checked your SWR on GMRS repeater channels (467.xxx MHz)?

 

I recently tuned a 1486 and used the cutting sheet to tune to/near 465 MHz (split the difference between 464 and 466). I ended up with an SWR right near 1.4:1, which was good enough for me. 

[WRUE951]

Good ole' homemade J-poles work great for GMRS..  Several 'how to's' to build them on a Google Search..  i built one for roughly $20 bucks.    

[AdmiralCochrane]

I've built a few for less than $20 at times.  It's possible to make a functional vertical antenna for even less.