[TowerTalk] Preferred type of coax to be used for jumpers in a multi-operator room ?

Wed Sep 4 20:16:04 EDT 2019

I have a length of Lmr-400 for sale if anyone is interested 

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> On Sep 4, 2019, at 7:31 PM, Gedas <w8bya at mchsi.com> wrote:
> 
> David, I have no personal experience with the M&P coax so I am just going by what I saw on their web page. Some observations:
> 
> It looks like it has very good initial shielding effectiveness but I wonder how the SE degrades after a fair number of flexes and regular use. It seems it is not rated for more then 15 bends at a 2" bend radius (that would be a show stopper for me).
> 
> The power capacity at 10m is only ~425W (on a hot day). The loss for a 100' length at 10m is better by 1.2 dB compared to RG-400 but given it's low power rating you would never use this coax for a long run out to the antenna anyway. Also I am not sure if you must use a special (proprietary) connector with this cable but if you do they might be more costly and more complex to install then those made for RG-400.
> 
> One of the nice things about RG-400 is it is rugged, flexible, and uses a Teflon dielectric. It can be bent tightly, even at very high power levels and elevated temperatures without degradation.
> 
> Maybe someone who has used this cable can chime in but I think I would stick with the RG-400 for the majority of ham applications.
> 
> Gedas, W8BYA
> 
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
> 
>> On 9/4/2019 6:03 PM, David Aslin G3WGN wrote:
>> Messi and Paolini have a double screened 5mm coax - Hyperflex 5.  Copper foil first screen then 88% coverage second screen. Inner is 19 strand bare copper; attenuation at 28MHz around half that of RG58.
>> This would seem to be a very well screened cable for short jumpers;  I'm wondering why I would choose RG400 at several times the price of the M & P product?
>> Hivemind thoughts?
>> 
>> I recall K9YC reminding us that the resistance of the screen is a factor in bonding our equipment via the coax, so this may be moot - larger cables have lower DC resistance and therefore a 10mm/0.4" cable may be a better choice.  Again, thoughts appreciated.
>> 
>> All relevant to my SO2R/MS/M2 station build
>> 73, David G3WGN  M6O
>> 
>> 
>> -----Original Message-----
>> From: Gedas [mailto:w8bya at mchsi.com]
>> Sent: 04 September 2019 20:32
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Preferred type of coax to be used for jumpers in a multi-operator room ?
>> 
>> It will depend on who makes the cables you are comparing. If both are
>> M17 rated then both should be double shielded and use silver coated copper conductors which is good but some manufactures may use 95% braid coverage while some may use less. Some may use 95% for both shields others may use 95% for the outer and less for the inner. Also the angle of the weave also affects the shielding effectiveness. This SE will also vary with frequency. But in general, esp for HF use, you will find both to have similar shielding performance as long as you stick to a known trusted & respected name brand. Also keep in mind the dielectrics are totally different between the two.
>> 
>> Gedas, W8BYA
>> 
>> Gallery at http://w8bya.com
>> Light travels faster than sound....
>> This is why some people appear bright until you hear them speak.
>> 
>>> On 9/4/2019 2:54 PM, Stig Lindblom wrote:
>>> Gents;
>>> 
>>> We are rebuilding a contest station operating room (HS0ZAR at HS0ZGD) and
>>> need to do a lot of new jumpers.
>>> 
>>> Ref. advise below from K9YC (tnx) we will use RG400 (or similar) for
>>> short jumpers.
>>> 
>>> Considering to use RG214 (double shield) for longer jumpers, and for
>>> coax-stubs as well.
>>> 
>>> How is the measured, or experienced, shielding of RG214 compared to
>>> the
>>> RG400 ?
>>> 
>>> 73 de Stig
>>> 
>>> LA7JO _ HS0ZGD
>>> 
>>> On 8/6/2019 6:50 AM, Gedas wrote:
>>> 
>>> And. the conductors are Silver plated, copper clad steel.
>>> 
>>> ------------------
>>> 
>>> Clarification for other readers. The center of RG142 is silver coated
>>> copper coated steel, the center of RG400 is stranded silver-coated
>>> copper. Both have double silver-coated copper braid shields.
>>> 
>>> Loss is about the same as RG58 -- in other words, fairly high. The
>>> principal virtue of these cables is their superior SHIELDING, which is
>>> a LOT better than most braided coax.  You only want to use this stuff
>>> for short jumpers.
>>> 
>>> I've been happy with at least two purchases of Harbour Industries
>>> RG400 that I've found on ebay from a US vendor.  Harbour Industries is
>>> based in VT, and has a presence across the border in QC. NA6O was
>>> happy with the RG400 he bought from China.
>>> 
>>> 73, Jim K9YC
>>> _______________________________________________
>>> 
>>> 
>>> 
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>>> http://lists.contesting.com/mailman/listinfo/towertalk
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