[TowerTalk] Heliax Connectors
Roger (K8RI)
K8RI-on-TowerTalk at tm.net
Tue Apr 20 19:02:40 PDT 2010
Ryan Jairam wrote:
> Unless someone is running at least 3x the legal limit, I doubt any
> amateur running legal amateur power levels will have any problem with
> either an N connector or PL259. Andrew N connectors can actually
> handle up to 10kW (peak) according to the spec sheets.
>
> High SWR may be a different issue but I try to avoid high SWR here.
> The only antennas I have that routinely operate under high SWR are fed
> with 450 ohm line.
>
> Anyway, my whole reason for using N was availability and cost.
> Performance is a non issue because under HF amateur applications at
> legal limit or less into a 50 ohm load there won't be any difference.
>
I operate the full band on both 75 and 160. That means the SWR may hit
8:1 which means very high voltages at times when running the legal
limit. I dislike open wire with a passion as every time some one runs
it at FD it interferes like crazy. When running high power the stuff has
to be well in the clear of everything and out of reach for safety. IOW
it takes special handling and looks antiquated, if not messy. Now there
is some real high voltage with 450 to 600 ohm open wire feed line. The
LMR-600 has very little loss even with the high SWR. I just need
connectors that will handle it. Steve found some nice ones for me, but
I still take them apart and open up the one bulkhead behind the Teflon
dielectric to get more clearance. I use LMR-600 for a 160 feed line,
pushing the legal limit. I've blown out N connectors on several
occasions on 75 with less than the legal limit out of a two hole 76A. I
even blew out a double female N connector. Man but that was hard to find
as I didn't expect to find the problem there. I'm now making my own
current baluns as shown in K9YC's RFI tutorial. They hold up, while the
little $30-$40 baluns many places sell, do not hold up at all well.
I can operate the entire 40 meter band using an RG-8X, or CNT-240 feed
line and N connectors and the legal limit, from end to end, but not 160
or 75. Also when running LMR-600 on 160 resistive losses are less of a
concern although I don't think they amount to much in RG8 size cables at
that frequency. BTW I did not like CNT-240 because of the fragile
braid. I need to get some LMR-240 and see if it's any better. I like the
low profile cables to the sloping dipoles as they don't swing around so
much or present the wind load of LMR-400. I've gone to using Davis
BuryFlex as the leads to the 75 meter half wave, center fed slopers.
The next step on 75 is to go to 6" diameter cage, sloping dipoles. On 40
I'm going to a beam.
N connectors are fine most of the time, but you have to make sure you
have the proper ones/size for the cable you are using and that is some
times a problem. Don't get the right size and they are not mechanically
sound, or conversely you have a problem getting the nut washer and
gasket over the jacket.
73
Roger (K8RI)
> Ryan, N2RJ
>
> On Tue, Apr 20, 2010 at 7:13 PM, Roger (K8RI) <K8RI-on-TowerTalk at tm.net> wrote:
>
>> Ryan Jairam wrote:
>>
>>> I would just get N connectors and adapters and use that instead.
>>> Practically nobody else but ham and CB use UHF connectors anymore.
>>>
>>>
>> To me the UHF are preferable to the N for HF if you run power and a high
>> SWR. I look at N as a mistake. If I didn't have so may connectors
>> already installed I'd go with the 7-16 DIN which might even be cheaper
>> now days.
>>
>> I've never noted any difference up through 2-meters although others
>> have. What we did different? I have no idea.
>>
>> 73
>>
>> Roger (K8RI)
>>
>>> Vy 73
>>> Ryan N2RJ
>>>
>>> On 4/20/10, john at kk9a.com <john at kk9a.com> wrote:
>>>
>>>
>>>> These connectors are no longer made and most dealers seem to be out of them.
>>>> Here is one dealer that has four of them and is asking $1500/each
>>>> http://antennasystems.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=L44P&Category_Code=LDF4con
>>>> .
>>>> If anyone does have any L44P or L44U connectors that they would like to get
>>>> rid of for a more reasonable price, please send me a direct email
>>>>
>>>> John john at kk9a.com
>>>>
>>>>
>>>>
>>>>
>>>> To: "Tower and HF antenna construction topics." <towertalk at contesting.com>
>>>> Subject: Re: [TowerTalk] Heliax Connectors
>>>> From: Steve Maki <lists at oakcom.org>
>>>> Reply-to: "Tower and HF antenna construction topics."
>>>> <towertalk at contesting.com>
>>>> Date: Mon, 19 Apr 2010 14:09:51 -0400
>>>> List-post: <towertalk at contesting.com">mailto:towertalk at contesting.com>
>>>>
>>>> Steve Bagley wrote:
>>>>
>>>>
>>>>> Ladies and Gentlemen:
>>>>> I have read so much information concerning what connectors to use for 1/2"
>>>>> heliax, I am thoroughly confused.
>>>>>
>>>>> I need to splice some heliax together for a long run, and terminate at the
>>>>> tower and shack.
>>>>>
>>>>> My arrestors are a standard SO-239 connector.
>>>>>
>>>>> I would prefer to use the connectors designed for the heliax vs standard
>>>>> 259's.
>>>>>
>>>>> Anyone have the appropriate part numbers and any concise input? Really
>>>>> appreciate it!
>>>>>
>>>>>
>>>> Assuming you're talking about Andrew LDF4, the Andrew part numbers are:
>>>>
>>>> L44Z - splice
>>>> L44P - UHF male
>>>> L44U - UHF female
>>>>
>>>> I'm not sure any of these are actually made anymore, but can be found in
>>>> stock at some dealers, and commonly at fleamarkets. Also RF Industries
>>>> (RFI) makes a UHF male for LDF4 if I'm not mistaken.
>>>>
>>>> 73,
>>>>
>>>> --
>>>> Steve Maki
>>>>
>>>> _______________________________________________
>>>>
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>>>
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