D130JN Assembly - Tap fiberglass on ground instruction?

[JohnDistai]

Just got my first external antenna, a Diamond D130JN discone. It included a set of supplemental instructions (blue sheet) with an odd instruction:

"Gently tap the fiberglass portion on the ground to release the element. Then assemble the antenna."

I'm puzzled. I did that (very gently), but I didn't see anything happen. Will someone please enlighten me about this? Is this for other Diamond antennas or versions without the connector?

Thanks!

 

[JohnDistai]

Is the element the top whip part of the antenna? (stop laughing!)

 

[iMONITOR]

I don't think that would apply the D130JN discone antenna as there is no fiberglass portion on mine, nor have I ever seen one on any other D130JN disone antennas. Maybe those directions are from another antenna that was tossed in the packaging accidentally. Did you buy it new from a dealer, or used from an individual?

 

[JohnDistai]

I bought it new from a dealer.

 

[bearcatrp]

Don’t recall anything fiberglass to tap on mine. Will see if I still have the instructions. If I do and don’t see anything like this, can scan it and send it to you.

 

[ko6jw_2]

I have two of these antennas and I never saw this instruction. I would ignore it. A few points:
1. The loading coil and the whip are not part of the discone. They are for operation on 6 meters.
2. Diamond says the antenna covers 25-1300MHz. This is hype. The discone covers about 110-1200MHz. Its performance on low band is not good.
3. A longer whip can be ordered from suppliers to increase low band coverage. I use a 48" whip that resonates the antenna at 42MHz for CHP.
4. I you don't need low band just unscrew the coil and the whip and set them aside.
5. If you want to use 6 meters the whip should be slightly shortened as it resonates at 50MHz.

Do not try to "tune" the antenna. There are three variables. The disc diameter, the skirt length and the spacing between the disc and skirt. That spacing cannot be changed. Altering the other two may produce unpredictable results.

Remember a discone trades off broadband coverage for gain (unity gain). They also have a higher angle of radiation which makes them good for aircraft.

 

[bearcatrp]

ko6w2, hate to break the bad news to ya but mine picks up HF as good as my wire did.

 

[freema22]

I'm struggling with my new D130NJ. I bought it to monitor a wide range from the aircraft band through the 700/800 MPSCS system operated by the State of Michigan. It is absolutely deaf for 700/800. I've tried everything I can think of to try and improve the performance. I get better reception with the set-top telescoping antenna (which is not great). I'm ready to throw this thing in the garbage.

 

[jeepsandradios]

What are you using for cable ? 700/800 has alot of loss in smaller cable at any distance. May be just cable loss.

 

[freema22]

LMR-400

 

[vagrant]

Your discone is fine for 110-500 MHz. At 700-800 the signals would need to be strong or a transmitter close by. An option is to use an antenna tuned for 700-800 along with a run of LDF4-50A coax, with some short and flexible patch cables at the ends. Still, you can try LMR-400 with those higher frequencies. Test it with your existing and the new 700-800 antenna.

You can then use a separate scanner/receiver to monitor that new antenna and coax run, or find a diplexer that splits at 500MHz to feed your single scanner.

Do not throw your discone in the trash. It is a fine wide band receive antenna for 110 to 500 MHz and around 52MHz if it has the whip on top connected.

 

[prcguy]

Through the lower half of a Discones 8:1 frequency range (like a D130) they have a low angle of radiation towards the horizon which would cover both the VHF and UHF air bands. About half way through their frequency range the radiation starts to point upward and at 800MHz they can easily be 10dB down at the horizon.

For best aircraft reception you want a wide and low radiation angle pointed at the horizon to pick up most distant aircraft. For high altitude aircraft nearby you don't really need much of an antenna because they are not that far away and very line of sight.

Remember a discone trades off broadband coverage for gain (unity gain). They also have a higher angle of radiation which makes them good for aircraft.

 

[bearcatrp]

Freema22, where is your antenna located? Outside or inside? If outside, how high?

 

[JohnDistai]

For mine, I'm using LMR-400, and I got it to listen to air and the local P25 simulcast (700-800 Mhz). I was considering a temp setup in the attic, but now I'm thinking of going whole-hog and putting a mast on my house after I've read the ARRL Grounding book and done that homework.

 

[krokus]

I'm struggling with my new D130NJ. I bought it to monitor a wide range from the aircraft band through the 700/800 MPSCS system operated by the State of Michigan. It is absolutely deaf for 700/800. I've tried everything I can think of to try and improve the performance. I get better reception with the set-top telescoping antenna (which is not great). I'm ready to throw this thing in the garbage.

What is the topography between you and the site(s) you are trying to monitor? Which site(s)?

 

[freema22]

Freema22, where is your antenna located? Outside or inside? If outside, how high?

Right now, it is temporarily on a 10-foot piece of conduit outside. The ultimate plan is to put it on the roof, but I wanted to give it a test run first to check the performance. Because of the poor performance thus far, I am reluctant to mount it on the roof, lest I have crappy reception from it. I don't like roofs and the less time I have to spend on them, the better.

 

[iMONITOR]

Because of the poor performance thus far, I am reluctant to mount it on the roof, lest I have crappy reception from it.

The only "performance" you'll get from a discone is wide-band coverage which can bring in noise and signals from undesirable sources. They typically have zero gain and do not perform great at any frequency.

 

[bearcatrp]

Right now, it is temporarily on a 10-foot piece of conduit outside. The ultimate plan is to put it on the roof, but I wanted to give it a test run first to check the performance. Because of the poor performance thus far, I am reluctant to mount it on the roof, lest I have crappy reception from it. I don't like roofs and the less time I have to spend on them, the better.

You need the antenna above the roof line for good reception. 10 foot test is to low.

 

[freema22]

You need the antenna above the roof line for good reception. 10 foot test is to low.

I disagree. The antenna is unobstructed in the direction of the repeater site and my old setup had few issues receiving the site.

 

[freema22]

I am really reaching the end of my rope with this situation. Here's a shot of the display of my scanner. The meter bounces between 4 and 5 bars with nothing heard. I've rebuilt my scanlist by importing from RR.



Below is a screenshot of my PSREdit500 settings for this system. Maybe I missed something there? I have switched the multi-site settings beween OFF-STAT-ROAM without any performance changes. I really appreciate all of the help.