[CQ-Contest] Station Re-Build - Coax

Thu Mar 14 14:28:45 EDT 2019

Hi Pete, 

I can easily wrap my Times Microwave RG-400 around my finger. 

But the improved shielding effectiveness of double shielded 
coaxial cables such as RG-400 and RG-214 doesn't provide a 
useful performance improvement except for multi-operator 
and SO2R stations. 

Just because RG-400 has greater than 90 dB shield effectiveness, 
1500 watt power handling capability ( at HF only), and one inch 
minimum bending radius, that doesn't mean that you need or will 
benefit from those capabilities. 

Small diameter coaxial cables such as RG-58 have relatively poor 
shielding effectiveness, roughly 40 dB or much worse for RG-58 
with less than 95% shield coverage. RG-213 with 95% shield 
coverage has roughly 55 dB shielding effectiveness. 

But there are only a few situations where greater shielding 
effectiveness of double shielded coax will improve the 
effectiveness of contest stations, for example: 

- when coaxial cables for receiving antennas must be bundled 
with coaxial cables connected to a transmitter in a multi-operator 
or SO2R station (an undesirable practice unless it cannot be 
avoided for some reason). 

- when coaxial cables must be run alongside a tower leg 
in a multi-operator or SO2R station. In this case, solid shield coax 
such as Heliax is more cost effective and significantly more 
resistant to physical damage and moisture intrusion than 
braided shield coaxial cables. 

RG-223 is much less expensive and has the same shielding 
effectiveness as RG-400 but its power rating is 100 watts at HF. 

73 
Frank 
W3LPL 

----- Original Message -----

From: "N4ZR" <n4zr at comcast.net> 
To: "Wayne Kline" <w3ea at hotmail.com>, "charlie carroll" <k1xx at k1xx.com>, cq-contest at contesting.com 
Sent: Thursday, March 14, 2019 12:48:38 PM 
Subject: Re: [CQ-Contest] Station Re-Build - Coax 

Oops. I did some more dissecting on the cable, and I'm wrong about the 
shielding. That leaves only the absence of printing - this is advertised 
as Harbour Industries RG-400 - and its stiffness. This stuff is quite 
hard to bend in even an 8" coil. Can anyone who has used real RG-400 
confirm whether it feels supple and flexible to the touch? I have one 
jumper in my station that looks like the same stuff, but which is very 
supple. I bought it at Dayton a few years aho, already connectorized. I 
can believe a 1" minimum bend radius with it, but not with the stuff 
from China. 

73, Pete N4ZR 
Check out the Reverse Beacon Network 
at <http://reversebeacon.net>, now 
spotting RTTY activity worldwide. 
For spots, please use your favorite 
"retail" DX cluster. 

On 3/13/2019 9:51 AM, N4ZR wrote: 
> 
> I just bought 10 feet of RG-400U (supposedly Harbour Industries) 
> through E-bay for $13. Belatedly, I learned it was coming from 
> China. It's now here, but I don't think it is for real - it only has 
> one shield, and is somewhat stiff. At least the inner conductor isn't 
> magnetic.There's no printing on the cable. 
> 
> Buyer beware. 
> 
> 
> 73, Pete N4ZR 
> Check out the Reverse Beacon Network 
> at<http://reversebeacon.net>, now 
> spotting RTTY activity worldwide. 
> For spots, please use your favorite 
> "retail" DX cluster. 
> On 3/12/2019 11:35 PM, Wayne Kline wrote: 
>> I third the sugjestion of the RG400 small enough for all the switching in a more then one radio setup. 
>> 
>> The tight bend radius the small diameter make for a clean instlation that coupled with the double shielding it’s a WIN WIN 
>> 
>> Watch Ebay or other surplus suppliers 
>> 
>> 
>> 
>> Wayne W3EA 
>> 
>> 
>> 
>> Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10 
>> 
>> 
>> 
>> ________________________________ 
>> From: CQ-Contest<cq-contest-bounces at contesting.com> on behalf of charlie carroll<k1xx at k1xx.com> 
>> Sent: Tuesday, March 12, 2019 10:23:06 PM 
>> To:cq-contest at contesting.com 
>> Subject: Re: [CQ-Contest] Station Re-Build - Coax 
>> 
>> Keith: 
>> A couple very similar candidate cables are RG-400 and RG-303. RG-400 is 
>> double shielded while 303 is single. They're good as interconnects 
>> because they have a small bend radius (about 1"). RG-400 uses 
>> multi-strands of copper for the center conductor; RG-300 uses copper 
>> clad steel. Either will handle 1500 watts at HF. 
>> 
>> 73 charlie, k1xx 
>> 
>> On 3/12/2019 7:51 PM, Keith Dutson wrote: 
>>> My multi-two station, with third spotting station, is being rebuilt into new 
>>> digs. I have a lot of 3-4 foot RG213 cables running between the amp, power 
>>> meter, tuner and switch. I have heard there may be a smaller cable that has 
>>> very little loss, but handles 1500 watts. I would appreciate any comments 
>>> on what is being used today. Thanks. 
>>> 
>>> 73, Keith NM5G 
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