[amsat-bb] LMR-400 direct to antenna or no?

[Norm n3ykf]

I use LMR-400 DB on the VHF side. With a 130' run it's lossy.
Previously, it was on both UHF and VHF.

Replaced the UHF side with LDF4-50A that was dumpster retrevial just
after an unnamed blue and white railroad ran their last train out.
Much better.

With a 130' run was lossy at UHF. Preamp is necessary. On the VHF
side, a preamp is usually un-necessary.

Rotator loops are 9913F7. Be sure to get the correct N connectors as
this has a larger center conductor. Several stranded strands can be
trimmed if they are unavailable.



On Thu, Mar 31, 2016 at 9:43 PM, w4upd <updwrb at bristor-assoc.com> wrote:
> I would do like I did to my 9913. This is rather stiff cable. I went a
> couple of turns loosely around the mast and around the boom for elevation. I
> would do this with the antennas at 0 elevation and 360/0 degree azimuth. In
> this way it acts like a simple spring which opens or tightens slightly as
> the rotation of the mast and/or boom occur. I had my 9913 this way for over
> 15 years without a problem. I suspect the LMR400 should work the same. In
> this way you are not inducing any losses with additional cables and
> connectors.
>
> Just my two cents.
>
> Reid, W4UPD
> Amsat: 17002
>
>
>
> On 3/31/2016 9:35 PM, Scott wrote:
>>
>> I hope to put up my first rotating antenna soon and just received a nice
>> length of LMR-400 to use. (regular, not "super-flex")
>>
>> Having never seen LMR-400 before, I did not know how flexible it would be.
>> I would call it "medium"... not stiff as a pipe but not floppy, either.
>>
>> My question is whether anyone using LMR-400 can recommend whether I should
>> attach it directly to my antenna (with slack loops, of course)?
>>
>> Or, should I get a few meters of something more flexible to attach to an
>> antenna that needs to be free to rotate 360 degrees?
>>
>> If a jumper is recommended, I would appreciate suggestions on what cable
>> would work best for the task.  The frequency for this project is 70cm.
>>
>> Thanks!
>>
>> -Scott, K4KDR
>> Montpelier, VA  USA
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>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb