On the bandwagon: RS Coax is crap

[KC2UGV]

Ok, I'm on the band wagon now. Rat Shack Coax is crap, for VHF.

I've not had a problem ever with my digi node. So, I get the antenna in place, and fed with rat shack coax.

Now, it stick on PTT. I came home last night to find my node on constant TX, hotter than a witches tit simmering in hell. Must have been keyed up for at least an hour :roll:

So, I disconnected power, let it cool for about 1.5 hours, and tested it again. Sho-nuff, stuck on transmit again...

Well, on to Hirch's for some cable...

[NQ6U]

What kind of coax was it--RG-8U, RG-58, etc? I found that switching my VHF cable runs to LMR-400 (with Type-N connectors) made a noticeable difference.

[KC2UGV]

What kind of coax was it--RG-8U, RG-58, etc? I found that switching my VHF cable runs to LMR-400 (with Type-N connectors) made a noticeable difference.

58... I don't think they carry anything but. Yeah, it's time to break down and get some good coax and connectors now, because at this time, my digi is still offline to prevent problems.

[NQ6U]

Yeah, good idea. The attenuation of RG-58 at VHF frequencies is horrendous and, of course, that loss is translated into heat. If you can't afford LMR-400 or something similar (try eBay, I got a good deal on some there), at least switch to RG-8U. It's still pretty bad at VHF frequencies but it's better than RG-58.

[KC2UGV]

Yeah, good idea. The attenuation of RG-58 at VHF frequencies is horrendous and, of course, that loss is translated into heat. If you can't afford LMR-400 or something similar (try eBay, I got a good deal on some there), at least switch to RG-8U. It's still pretty bad at VHF frequencies but it's better than RG-58.

Well, it boils down to a combination of the following, most likely:

* Shit poor coax for VHF
* New Antenna (And, common mode issues)
* Antenna too close to transmitter

When it was last set up, I was using Belden Coax (8410, I think. TV coax). It worked very well. However, the antenna was a groundplane 1/4 wave; and it was located about 15 ft away, as the crow flies.

Now, I'm using RS RG-58 coax, it's a vertical dipole, and it's only about 3 feet away.

I don't think common mode (I'm not hearing anything on a crap set of speakers nearby, my du jure test for common mode issues), so I'm guessing leakage from the cable, locking the PTT serial line. Or, direct coupling of the PTT control to the antenna, keeping it keyed up.

[KG4CGC]

58 is crap for most things. Back in the day, even their RG-8 was a crapshoot but they did carry better material just before it was phased out of their stock. RS stuff is the only brand that I've seen that the braid tarnishes. This means there are large enough openings in the outer cover to let in abundant air and maybe water.

[ka8ncr]

If you're nice, you can get LMR-400 from Hutton for well under a buck a foot. Ask the sales guy for odd lots and they're happy to unload it, just be prepared to buy 30' or 223'. Times Microwave has a crimp N for that cable that is truly heavenly.

Seeing that might be a bit rich for some hams, there's Comscope RG-11. It's 75 ohm cable, but I've used it for VHF and UHF and it worked fine. That stuff is cheap.

[kd8dey]

Been using lmr-240uf myself for VHF/UHF

dunno how good this stuff is BUT I have been wanting to give it a try

http://www.copper.com/cart/product_i...oducts_id=1429

[PA5COR]

75 foot runs here up to the Diamond X 510N, or to the 11 element Flexa yagi for 2 and the same for the 23 element flexa 70 cm.
Ecoflex 15 ( mm) or about the same as LMR 600.
In the van 8 feet Aircell 7 ( mm) very low loss.
For the vertical L 160-20 meter antenna Aircell 7 40 feet to the tuner MFJ 998, running 1 KW through it.
Rest of the coax on HF-6 is Aircom plus, the same as LMR 400.

All N connectors.
The EWE antenna Aircell 5 just recieve.
I don't skimp on coax or connectors.

[W5GA]

Ratshack RG-8 is the only coax I've ever seen flash over with high power on it.