[amsat-bb] Exciting Coax

Tue Jan 23 22:26:45 UTC 2018

Thanks Greg, Norm, Diane, WF1F, and Bob for the effort of your kind answers!

73

Mark W9AT

-----Original Message-----
From: Greg D [mailto:ko6th.greg at gmail.com] 
Sent: Tuesday, January 23, 2018 2:52 PM
To: Norm n3ykf
Cc: Bob- W7LRD; anderson58625; Amsat BB
Subject: Re: [amsat-bb] Exciting Coax

Ok, fair enough.  F7 is different than the original 9913, and that is an
important distinction.  Bob's comment (which I quoted) was about the
original 9913.  The F7 variety shouldn't be as susceptible to water, but
then it also isn't quite as good as (dry) 9913 or LMR-400. 

But to the original question, which included a point about covering
microwave bands, none of the RG-8-ish type cables are appropriate for more
than a few feet on those bands.  Except for the short flexible portion
around the rotor, LMR-600 or hardline is needed, or mount a weather proof
transverter up on the tower to shorten the microwave portion of the feed.  I
still use a higher-grade cable for UHF, as my run is over 60' from rig to
antenna.  Below that, it's more a matter of availability and cost.  Just
don't go with the really skinny stuff
(RG-58 or RG-8X), because of both higher loss and lower power handling
capability.

A good comparison table I found is here: 
https://mapleleafcom.com/PDFs_Downloads/CoaxLossChart.pdf

Greg  KO6TH

Norm n3ykf wrote:
> 9913 is not 9913F7
>
> Google is your friend, or perhaps if one is lazy, not.
>
> Norm n3ykf
>
> On Tue, Jan 23, 2018 at 12:33 PM, Greg D <ko6th.greg at gmail.com> wrote:
>> I've got hardline for my 60' runs on 70cm, and 1.2 ghz.  Really works 
>> a LOT better than 9913, especially with the water problems.  Besides 
>> at the connectors, the local squirrel population likes to gnaw at 
>> stuff, and all it takes is one small chew to ruin the entire run.  
>> With "regular" (solid innards) coax, the wound can be taped over with 
>> electrical tape, since they don't seem to like the braid.  Even the 
>> smallest nick in 9913 will eventually be fatal.
>>
>> Greg  KO6TH
>>
>>
>> Bob- W7LRD wrote:
>>> For 2 & 70cm I use LMR400.  LMR is better (in my opinion), in that it's
more flexable, 9913 can get water inside.  Unless coax connectors are super
sealed.
>>> 73 Bob W7LRD
>>>
>>>> On January 22, 2018 at 6:03 PM anderson58625 <anderson58625 at gmail.com>
wrote:
>>>>
>>>>
>>>> Reading the subject line, I may have somehow mixed sarcasm with a 
>>>> potential pun (eye of the beholder!) <grin>.  Sorry for that.
>>>>
>>>>
>>>>
>>>> I seek to avoid investing in a set of cable producing hardware (or 
>>>> assembled
>>>> cables) which I will regret later.  I am hoping to get some 
>>>> guidance regarding coax for:
>>>>
>>>> 1)      IF patch between equipment (male-male BNC's)
>>>>
>>>> 2)      2m feedline (N-connectors) (<50')
>>>>
>>>> 3)      70cm feedline (N-connectors) (<50')
>>>>
>>>> 4)       A later potential for feedline carrying microwave frequencies
>>>> (>1GHz)
>>>>
>>>>
>>>>
>>>> The frequency & loss-rate charts for coax are informative, but I'm 
>>>> not sure I'm seeing which connectors will fit what cable 
>>>> brand/types.  With the variables of loss, dimensions, flexibility, 
>>>> and potential proprietary crimping systems, etc., I don't have 
>>>> enough experience or information to confidently make an online 
>>>> materials order.  Things were much easier down here with just HF 
>>>> frequencies, RG-213, and good quality (weather protected) PL-259's! 
>>>> <grin>
>>>>
>>>>
>>>>
>>>> For IF patch cables, I figure these are conveying HF so the cable 
>>>> type/loss at 1-3' isn't very important.  But, there is also 
>>>> shielding:  A consideration?
>>>>
>>>> .       Any thoughts on IF cables?
>>>>
>>>> .       Plus, I've never attached a BNC to a cable.  Easy?  Avoid it?
>>>>
>>>> .       Plan on a new crimper/die?
>>>>
>>>> .       Or, if premade would be cheaper (just a few IF patch cables),
any
>>>> quality sources to recommend?
>>>>
>>>>
>>>>
>>>> For the 2m & 70cm feedlines, I know flexibility may be a 
>>>> consideration on rotating/elevating masts.  Of course, I'm sure a 
>>>> rigid feedline may be superior elsewhere, but I am not at that 
>>>> point yet.  Still, advice on that subject is gratefully 
>>>> appreciated.  I need to provide good questions to hope for good
answers, so what feedline you would recommend for:
>>>>
>>>> .       Reasonable flexibility/portability
>>>>
>>>> .       2m-23cm
>>>>
>>>> .       Modest power
>>>>
>>>> .       <50'
>>>>
>>>> .       For use with n-connectors
>>>>
>>>>
>>>>
>>>> The benefit of you knowledge and experience is much appreciated.
>>>>
>>>>
>>>>
>>>> 73
>>>>
>>>>
>>>>
>>>> Mark W9AT
>>>>
>>>>
>>>>
>>>>
>>>>
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>> _______________________________________________
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>> Opinions expressed are solely those of the author, and do not reflect the
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>> Not an AMSAT-NA member? Join now to support the amateur satellite
program!
>> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb