Which type of cable for Diamond Discone?

[AZ645]

I just picked up a Diamond Discone antenna and will be installing on new home. I was wondering if anyone has advice on type of cable to use? I am thinking of going with LMR 240 Ultra Flex, 75 ft run. I was going to go with LMR 400, but I've used in the past and have found it to be very unflexible. Any other recommendations?

 

[n5ims]

Try the ultraflex version of LMR 400 if you were happy with the performance but don't want the installation hassle for your new run. It's basically the same cable but uses a stranded center core and different plastic for the insulator between it and the shield to make it much more flexible. It costs just a bit more but will have lower loss than the LMR 240 will.

 

[NC1]

That is a long run for frequencies above 400 MHz and will suffer from heavy Db loss. If you cannot possibly make the length substantially shorter, I would go with the LMR-400 even if it is a pain to install - you only have to do it once.

Look up the loss charts for the different bands and coax cables, you will see what I mean.
Here is a link to one of them:

Coax Attenuation Chart

 

[mmckenna]

I agree, 75 feet is a lot.

You can try one of the online coaxial cable loss calculators to get an idea…

At 75 feet, 855MHz here are some numbers:
RG-6 6.8dB of loss, or almost 80% of your signal.
LMR-240 5.5dB of loss, or a bit over 70% of your signal.
LMR-400 2.83dB of loss, or just a bit less than 50% of your signal.
LMR-600 1.83dB of loss, or about 35% of your signal.
1/2" Heliax, 1.5dB of loss, or about 30% of your signal.

Any way you can move the radio and antenna closer together?

 

[lou9155]

i love lmr 400..really improved my scanner listening

 

[chief21]

I agree, 75 feet is a lot. <<snip>> Any way you can move the radio and antenna closer together?

As mmckenna advises, your best option is to move the antenna closer;

Failing that, I wouldn't use anything less than high-quality, LMR400-type cable.

By the way, be sure to order the correct coax connector for your Diamond discone... Some are UHF and some are N.

 

[Ubbe]

Use RG6, it's flexible enough, and add an amplifier at the antenna and you'll end up with gain instead of loss. Something that even the most expensive coax can't do on its own. Add a variable attenuator at the scanner and you can't go wrong. https://www.ebay.com/itm/Variable-Attenuator-0-20-dB-F-Kupplg-F-Kupplg-0-1-2400-MHZ/153096386799

If you get a low noise amp, 0.5-1.5dB NF, you will have a better signal than the scanners input amplifier can provide. It's a win-win situation. https://www.ebay.com/itm/Ultra-Low-...000-MHz-Gain-20dB-NF-0-65-dB-LNA/283092038093

/Ubbe

 

[iMONITOR]

If you use a preamp, ideally you want it at the antenna end of the coax, not at the radio end.

 

[AZ645]

Thanks to all for the really helpful responses.

 

[nyair1]

I used Bury-flex lmr 400 on my discone. Im running about 50ft of it. Got it online at one of the ham radio outlets at a good price all made up with the connectors. Cant think of the name of the site for the life me me lol. Was a good deal. I did alot of looking around for a deal on it.

Thanks to all for the really helpful responses.

Sent from my SM-G920V using Tapatalk

 

[cmdrwill]

Plus One for nyair1

Davis RF Co. - Bury-FLEX Flexible Low-Loss Coax

Good stuff ...