Centerfire Discone Antenna

[nyscan00]

Im looking into the Centerfire Discone antenna $23.00
http://www.centerfireantenna.com/scan.html
Does any one own this discone? any thoughts/ comments pro's/con's?
How does this compare to teh radio shack discone? $70.00
http://www.radioshack.com/product.a...me=CTLG_001_002_007_000&product_id=20-043

:arrow: Please let me know. Thanx

 

[Pro-95]

Disclaimer: I work for RadioShack. So I might be biased.

I put together a RS Discone from a broken one I had returned. It was the plastic center piece that had broken. I super-glued it back together and put it on the roof.

The results: Prompted me to begin building my own antennas. The first antenna I built caused me to remove the discone and toss it off the roof. Don't get me wrong the antenna works ok in all bands and is omnidirectional but........

Anything, that does everything, doesn't do one thing, well.

Note: I am not using the antenna for TX.

$23 bucks is a fairly cheap expenditure. If it works great if not, you didn't break the bank plus you can tell everyone here how well it does or doesn't work.

 

[LarrySC]

The centerfire, like most discones has a SO-239/PL-259 connector. These are not rated for 800MHz. Only thru UHF. You would have to put an "F" adp on this and run 75ohm coax. Using a regular soldered PL plug will cause loss. To insert the adp does not allow for loss. The loss is in the fact that the signal may have to travel thru the solder between the wire and casing of the pin.

 

[N_Jay]

The centerfire, like most discones has a SO-239/PL-259 connector. These are not rated for 800MHz. Only thru UHF. You would have to put an "F" adp on this and run 75ohm coax. Using a regular soldered PL plug will cause loss. To insert the adp does not allow for loss. The loss is in the fact that the signal may have to travel thru the solder between the wire and casing of the pin.

ErrRR???? :?

Yes, a SO-239/PL-259 is not rated at 800 MHz.
Putting an adaptor on it does not fix that problem.
The issue is the design of the connector is not a constant impeadance at frequencies that high, and most manufacturers do not use insulators which are good at that frequency.

It has NOTHING To do with the solder.

And where did the 75 ohm issue come in? That lost me completly!

 

[fourwd1]

The centerfire, like most discones has a SO-239/PL-259 connector. These are not rated for 800MHz. Only thru UHF. You would have to put an "F" adp on this and run 75ohm coax. Using a regular soldered PL plug will cause loss. To insert the adp does not allow for loss. The loss is in the fact that the signal may have to travel thru the solder between the wire and casing of the pin.

ErrRR???? :?

Yes, a SO-239/PL-259 is not rated at 800 MHz.
Putting an adaptor on it does not fix that problem.
The issue is the design of the connector is not a constant impeadance at frequencies that high, and most manufacturers do not use insulators which are good at that frequency.

It has NOTHING To do with the solder.

And where did the 75 ohm issue come in? That lost me completly!

Totally lost me too.
Adapters would add loss.
A TNC or N connector would be better at 800.
I think the 75 ohm coax was to go with the F connector, for whatever reason there is an F connector. Except maybe that comes from F connectors are used for TV applications and TV signals cover the frequency range in question ???

 

[LarrySC]

The scanner will operate with 75ohm coax just as well as 50ohm. Using the adp "F" to PL allows installation of AB or ABC swithes as well as splitters. This is much harder to do with RG-8 or 8x or mini 8. By the way these adps can be purchased with gold plated center pins from Pan Pacific for insertation in to the SO239. I have them myself. In a strong RF area you will never notice the loss in this type of installation. I dont like antennas with type of connector myself but for special needs of matching antenna to a special scanner then I use the special adps.

 

[OutPost]

CenterFire Discone 25 - 1300

Well....I chopped mine up !! It was at the top of my mast....loon' pretty up there and about 8 feet below is my RS (old) ground plane. The RS worked better. The coax for the RS ground plane is RG6. The coax to the CenterFire Discone is RG8X-95.

The CenterFire received aircraft and military pretty good, but 800mhz to 900mhz reception was nil. So..... I chopped-off all the elements to the 900 mhz formula and I was able to receive 800 and 900 mhz reception, but very scratchy, as opposed to my little stub cell phone antenna on my metal roof, which recieves very well..hmmm.

What do you think is the problem?? Is it the coax (RG8X)? I would like to replace my little stub CenterFire with a good Discone. What do you all think? Can I get away with the RG8X and a new antenna? To replace the coax will be a pain? The RG8X is longer than I need, is that the problem?? It's 50 feet long. The CenterFire is at the top of a 30 foot mast with an FM antenna below it and then the old Radio Shack groundplane.

Signed,
800 Blues

 

[K5MAR]

I'm not familiar with the centerfire, but your coax is killing your reception. I wouldn't use 8X for anything above 100 MHz myself. The RG-6 (I use the QS, Quad Shield, version) is a much lower loss in the UHF and up ranges. And you should always use the shortest piece of coax needed to get from antenna to scanner.

It doesn't matter how good your antenna is if your coax can't get the signal to the radio. I've got 40 ft of tower sitting on my back porch, when it goes up all my antennas that work above 30 MHz will be fed with LMR-400.

Mark S.

 

[OutPost]

Mike.......

Thanks for that info, I will change over to LMR400 and use the 8X for my HF Dipole.

Happy New Year