[TowerTalk] Andrew CNT 400 and Picking Low Loss Cable-DAVIS RF Co. responsec

Tue Mar 25 10:52:16 EDT 2008

Regarding the cost effectiveness of using CNT-400 (or LMR-400) vs RG-213 (or similar solid dielectric 50 ohm cables):

LMR-400 has only about 0.4 dB less loss per 100 feet at 28 MHz than RG-213.  It would take a minimum cable length of 250 feet before a 1 dB improvement would be realized at 28 MHz, and longer cable lengths for lower frequency HF bands.

For many ham installations, a more important question is: how much increased loss should I expect in my coaxial cable after I install it?

Most flexible coaxial cables use a PVC jacket that is very susceptible to abrasion from handling.  Never drag anything over the jacket of a PVC jacketed cable, it cuts like butter.  PVC jacketed cables are also
susceptible to wind induced abrasion damage on a tower.   All it takes is a pin hole in a coaxial cable and rain will begin to penetrate the jacket.

Perhaps a more cost effective investment would be a more abrasion resistant coaxial cable with a polyethelene jacket, such as Davis Bury Flex.  While any flexible jacketed cable should be handled and installed to avoid abrasion damage, polythelene jacketed cables can be expected to provide longer service with lower loss.

73
Frank
W3LPL

---- Original message ----
>Date: Mon, 24 Mar 2008 13:33:40 -0400
>From: "Steve Davis" <davisrf at comcast.net>  
>Subject: [TowerTalk] Andrew CNT 400 and Picking Low Loss Cable-DAVIS RF Co. responsec  
>To: <towertalk at contesting.com>
>Cc: gi0wlw at btinternet.com
>
>Hi Hugh,
>
>"CINTA"  CNT 400 is a Times Microwave LMR 400 knock off. Virtually the same, 
>but made in China under the auspice of Andrew Corp.  Andrew, for the most 
>part, has been synonymous with good to high quality and a leader in 
>broadcast associated materiel.   Others (Harbour, Commscope) have done LMR 
>knock-offs but having been in the wire/cable/RF connector and related 
>commercial biz for years, I have seen the LMR name still highly prevail. 
>More importantly, I have refrained from selling CINTA , although less 
>expensive vs. LMR, because even before the quality issues of various China 
>products became even more greatly  illustrated over the last year, I have 
>input as to the varying QC of this CINTA product....thus I will not sell it. 
>However, if you are using at HF, and if you have a supplier who would accept 
>your test results, or give you a no-fee return if n/acceptable (even using 
>an MFJ type analyzer), you stand a reasonable chance at finding at HF that 
>your cable will perform electrically well (CINTA 400 will have same 
>attenuation and electrical characteristics, within very small tolerance, if 
>any,  of LMR 400, when the dielectric was "brewed and extruded properly". 
>Also, look closely at the specs of either LMR400 or Cinta vs. the length you 
>need vs.  the actual attenuation and then compare to a good RG-213 vs. the 
>cost comparison and see if you really need
>the possibly slight attenuation advantage (to each his own of course, and to 
>each budget vs. $/dB non-attenuated).   Paying extra for a low loss cable 
>such as this, for HF, is often this sort of close comparison.
>  LMR 400 specs below 30 MHz may be on their graph, or contact me direct and 
>give me a couple freq's, or go to TimesMicrowave.com ,  choose the LMR 
>product category, or better yet, try their on-line calculator for 
>attenuation, a great tool, and you can pick many RG cables they make, to see 
>attenuation comparisons (varied by exact freq and exact length), then come 
>to DAVIS RF and we will get you an equivalent cable (or we can provide the 
>more expensive Times or Belden) that will perform very close, or same, as 
>Times or Belden).... of course at highly competitive pricing.
>If I can help further, just let me know.
>     73,
>Steve Davis, K1PEK
>
>DAVIS RF Co.
>
>Commercial Wire, Cable, RF Connectors and Custom/Specialty Cable Design 
>Engineering
>
>sdavis at DavisRF.com
>
>978-369-1738
>
>
>
>Date: Mon, 24 Mar 2008 09:35:57 -0000
>From: "Hugh Anthony Quinn" <gi0wlw at btinternet.com>
>Subject: [TowerTalk] Andrew CNT400.
>To: <towertalk at contesting.com>
>Message-ID: <003f01c88d92$7727d560$0200a8c0 at acw3559>
>Content-Type: text/plain; charset="iso-8859-1"
>
>Is this coax suitable for use at HF?
>The spec sheets on the web quote loss figures for 30mhz and above.I can get 
>some here in Ireland at a good prrice,but only if it is suitable for HF.
>
>Has anyone any experience of using it?
>
>Hugh  GI0WLW
>
>
>Tel:  978-369-1738     Fax:  978-369-3484
>NOTE: Please include all past email history with all followup emails until 
>your order or inquiry is complete. Thank you.
>
>Steve Davis, Jeff Stimson and the staff of the
>
>        DAVIS/ORION Group of Companies
>Where Customer Satisfaction is our Premier Goal
>
>~ Davis RF Co., Div. of Orion Wire Co.,Inc.
>Distribution to numerous industries,  Andrew
>Heliax; Times Microwave LMR; RFS Celwave and others.
>Cable design engineering. RF Peripherals.
>www.davisRF.com
>Tel: 1-800-328-4773 (1-800-DAVIS RF) Tech'l: 1-978-369-
>1738, Fax: 1-978-369-3484
>
>~ DAVIS/ORION Marine Wire and Cable Co., Distribution and Design: UL/USCG 
>Marine Stds.  Tel: 877-242-2253  Fax: 603-787-2221 (Direct tel to Steve 
>Davis: 978-369-1738 or Fax: 978-369-3484)
>
>~Orion Wire Co., Inc., Design Engineers of Specialty/Custom Cable
>Tel: 1-800-328-4773, 1-603-787-2200 Fax 1-603-787-2221,
>email: j_stimson at davis-orionwiregroup.com
>www.davisRF.com
>
>
>----- Original Message ----- 
>From: <towertalk-request at contesting.com>
>To: <towertalk at contesting.com>
>Sent: Monday, March 24, 2008 12:00 PM
>Subject: TowerTalk Digest, Vol 63, Issue 57
>
>
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>> Today's Topics:
>>
>>   1. Andrew CNT400. (Hugh Anthony Quinn)
>>   2. Re: Johnson Matchbox (Bill N1eY)
>>   3. Re: Johnson Matchbox (sabrams at nycap.rr.com)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Mon, 24 Mar 2008 09:35:57 -0000
>> From: "Hugh Anthony Quinn" <gi0wlw at btinternet.com>
>> Subject: [TowerTalk] Andrew CNT400.
>> To: <towertalk at contesting.com>
>> Message-ID: <003f01c88d92$7727d560$0200a8c0 at acw3559>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Is this coax suitable for use at HF?
>> The spec sheets on the web quote loss figures for 30mhz and above.I can 
>> get some here in Ireland at a good prrice,but only if it is suitable for 
>> HF.
>>
>> Has anyone any experience of using it?
>>
>> Hugh  GI0WLW
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Mon, 24 Mar 2008 07:19:22 -0400
>> From: Bill N1eY <whobulk3 at comcast.net>
>> Subject: Re: [TowerTalk] Johnson Matchbox
>> To: Jim Brown <jim at audiosystemsgroup.com>
>> Cc: Towertalk <towertalk at contesting.com>
>> Message-ID: <47E78E3A.2040900 at comcast.net>
>> Content-Type: text/plain; charset=UTF-8; format=flowed
>>
>> Well,  aren't there two versions of the Johnson Matchbox?  One was lower
>> power and the other was QRO.
>>
>> Jim Brown wrote:
>>> On Sun, 23 Mar 2008 21:32:43 -0700, Tom Osborne wrote:
>>>
>>>
>>>> Ran 500 watts with the SB-200 and it didn't even get warm.
>>>>
>>>
>>> Dissipation depends on the voltage and current in individual
>>> components, which in turn depends on the exact values of complex
>>> impedances being transformed, the frequency, and, of course, the
>>> power level. A capacitor that runs cool under one set of conditions
>>> may go up in smoke under a different set.
>>>
>>> Not to worry -- excessive dissipation is usually signalled by a
>>> special alarm that seasoned hams know well -- you begin to smell
>>> them getting warm!
>>>
>>> 73,
>>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Mon, 24 Mar 2008 08:48:09 -0400
>> From: <sabrams at nycap.rr.com>
>> Subject: Re: [TowerTalk] Johnson Matchbox
>> To: "Towertalk" <towertalk at contesting.com>
>> Message-ID: <000d01c88dad$50b9ed80$6500a8c0 at userg2asvv4l2m>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> reply-type=original
>>
>> Many years ago I ran a Heath Warrior at 800w thru my 250 Matchbox and it
>> never got warm, but when I looked inside, the plastic(?) coil form had
>> melted around the coil wires . Check inside!  GL  73  Saul  K2XA
>> ----- Original Message ----- 
>> From: "Jim Brown" <jim at audiosystemsgroup.com>
>> To: "Towertalk" <towertalk at contesting.com>
>> Sent: Monday, March 24, 2008 12:59 AM
>> Subject: Re: [TowerTalk] Johnson Matchbox
>>
>>
>>> On Sun, 23 Mar 2008 21:32:43 -0700, Tom Osborne wrote:
>>>
>>>>Ran 500 watts with the SB-200 and it didn't even get warm.
>>>
>>> Dissipation depends on the voltage and current in individual
>>> components, which in turn depends on the exact values of complex
>>> impedances being transformed, the frequency, and, of course, the
>>> power level. A capacitor that runs cool under one set of conditions
>>> may go up in smoke under a different set.
>>>
>>> Not to worry -- excessive dissipation is usually signalled by a
>>> special alarm that seasoned hams know well -- you begin to smell
>>> them getting warm!
>>>
>>> 73,
>>>
>>> Jim K9YC
>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> TowerTalk mailing list
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>>
>> End of TowerTalk Digest, Vol 63, Issue 57
>> *****************************************
>> 
>
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