Tram Tram 1411 Base Scanner Antenna (Discone)

[BC2001]

Hi everyone. I bought a Tram 1411 antenna and received it Tuesday; and I put it up the same day.

The antenna is on a pole and it is about a foot or so above my roof. For some reason, it does not pick up nearly as much as my little magnet mount antenna that was in the same place and at an even lower position. I am using PL-259 cable and have it connected to a BNC adapter to my scanner (BCD536HP).

I live in a very rural area, so I understand that maybe some of it. However, since my magnet mount antenna receives much better, I think that either the antenna is messed up, or I am doing something wrong. Any help would be appreciated.

And just FYI, I set everything up the way it is supposed to be; all parts are in the correct place.

Thanks again for any help, it is greatly appreciated.

 

[mmckenna]

Discone antennas have 0dB of gain. So if your magnetic mount antenna was a design that provided some gain on the frequencies you listen to, it's entirely possible that it did work better.
What type/brand/model is your mag mount?

How about your coaxial cable? What type and how long is it? Do you have excess cable, or is it just long enough?
What frequencies/bands are you listening to? Discone antennas can perform poorly on some higher and lower frequencies.

 

[Ubbe]

If you compare antennas at 800MHz then it's probably what it is. A standard size discone works equal to a short 1/4 wave lenght GP antenna up to maybe 500MHz then it deterioates as the directive loob points more to the sky than the horizon. If you have a magnet mount gain antenna, with a coil in the middle of the element or at the bottom, then the difference are even more noticable.

You can cut all elements to half if you only need to receive 160MHz and upwards and then it will work better at 800MHz, but still not as good as a gain antenna made for the 700-900MHz band.

/Ubbe

 

[BC2001]

Discone antennas have 0dB of gain. So if your magnetic mount antenna was a design that provided some gain on the frequencies you listen to, it's entirely possible that it did work better.
What type/brand/model is your mag mount?

How about your coaxial cable? What type and how long is it? Do you have excess cable, or is it just long enough?
What frequencies/bands are you listening to? Discone antennas can perform poorly on some higher and lower frequencies.

Hey. Thanks for the reply.
My magnet mount antenna what the Whistler WMM-460.I am using RG-58 PL-259 cable, and I have like 5 or so feet of extra cable. The reason I have the extra cable is that radioshack only had the cable in 20'each. One 20' wasn't enough so I bought another 20 feet and an adapter.
But I did think about that, so I went outside with my handheld scanner where it was close enough to the antenna (so I wouldn't have to use the extra cable) and I disconnected the extra cable and adapter. Unfortunately, it still didn't receive well.

I am listening to 150 MHZ stuff & 450 MHZ.

 

[mmckenna]

That's an odd antenna.
Probably has some gain on 450MHz. Looks like it's ~sort of~ 1/4 wave on VHF.

So, yeah, I could see it working better on UHF compared to the discone.

Ideally you would want to use better coaxial cable, 40 feet of RG-58 is going to have a lot of loss. The 0dB gain of the discone isn't helping anything.

The benefit of a discone antenna is that they are very broad banded, as in the work OK across a wide section of the spectrum. The drawback is they have no gain, and the radiation patterns get a bit high as you go up in frequency.

If VHF and UHF are all you listen to, then a dedicated dual band antenna with some gain would have been a better choice.
But if budget is tight, you do the best with what you've got.
Maybe try raising it a little higher if you can. Make sure the coaxial connections are clean and weather sealed. Make sure there's no strain on the connector, support the cable on the mast so it's not pulling down on the connector. Double check all your connections.

One thing you can do if you have a multimeter or continuity tester:
Check for continuity between the top "disk" and the bottom "cone" on the antenna with the coax disconnected at the antenna. There should be no continuity between those. If there is, something is damaged.
Next, check your coaxial cable from end to end. You might have to remove it to do this, but check for continuity from the center pin on one end to the center pin on the other. There should be continuity.
Do the same with the outer shield, end to end, there should be continuity.
With the coax still disconnected from the radio and antenna, check for a short circuit between the center pin and the outer shield. If there's a short, you have a bad cable, bad connector, etc.

 

[BC2001]

That's an odd antenna.
Probably has some gain on 450MHz. Looks like it's ~sort of~ 1/4 wave on VHF.

So, yeah, I could see it working better on UHF compared to the discone.

Ideally you would want to use better coaxial cable, 40 feet of RG-58 is going to have a lot of loss. The 0dB gain of the discone isn't helping anything.

The benefit of a discone antenna is that they are very broad banded, as in the work OK across a wide section of the spectrum. The drawback is they have no gain, and the radiation patterns get a bit high as you go up in frequency.

If VHF and UHF are all you listen to, then a dedicated dual band antenna with some gain would have been a better choice.
But if budget is tight, you do the best with what you've got.
Maybe try raising it a little higher if you can. Make sure the coaxial connections are clean and weather sealed. Make sure there's no strain on the connector, support the cable on the mast so it's not pulling down on the connector. Double check all your connections.

One thing you can do if you have a multimeter or continuity tester:
Check for continuity between the top "disk" and the bottom "cone" on the antenna with the coax disconnected at the antenna. There should be no continuity between those. If there is, something is damaged.
Next, check your coaxial cable from end to end. You might have to remove it to do this, but check for continuity from the center pin on one end to the center pin on the other. There should be continuity.
Do the same with the outer shield, end to end, there should be continuity.
With the coax still disconnected from the radio and antenna, check for a short circuit between the center pin and the outer shield. If there's a short, you have a bad cable, bad connector, etc.

Okay. Do you think if I were to get a better cable it would help some? If so, what would you suggest? Unfortunately, I do not have a multimeter or anything like that. And I will look into trying to raise it higher.

 

[mmckenna]

Okay. Do you think if I were to get a better cable it would help some? If so, what would you suggest? Unfortunately, I do not have a multimeter or anything like that. And I will look into trying to raise it higher.

If VHF and UHF are your primary targets, here's what I'd suggest:
Get a dual band antenna that has some gain. You need to get one designed for the commercial/public safety frequencies, not the amateur bands: https://www.theantennafarm.com/catalog/diamond-x50nc2-7303

Get it up as high as you safely can. VHF/UHF tend to be line of sight, so your antenna needs to have a clear view of the transmitting antenna. The higher up you get it, the farther it can see.

Use the best coaxial cable you can afford. 35 feet isn't a lot, so you don't need to go overboard. Times Microwave LMR-400 is good middle of the road stuff, but it can be a bit pricey. It's worth it, though. You could probably run some higher end RG-8 (not the cheap stuff) and still get pretty good results.