Thanks to everyone for their input! I appreciate all the responses. I believe
Jeff and Jim have my coax identified. I would still be scratching my head
trying to find something on it. It’s old, but still looks good.
Based in the inner and outer conductor diameters, I am sure it is not 75 ohm
cable. I have used thousands of feet of 3/4” CATV hardline and the center
conductor is less than half the diameter of this stuff. I wish it were as easy
to make good connectors for Heliax as it is for 3/4” CATV hardline. I’ve
probably made 50 or more using a plumbing fitting and an SO-238. They will self
thread on the end of 3/4” hardline using a wrench and a little Noalox. I don’t
believe I ever had a failure.
Speaking of 3/4” CATV hardline, if you can talk a local CATV provider into
giving you some, get it. It’s wonderful stuff, especially when it’s free. I
was lucky enough 25 years ago to have the local CATV company tell me I could go
to their yard and take any reels that had less than about 300 feet. They were
replacing everything in town with new coax and anything less than 300 feet of
the new stuff was of no use to them. I think I got about 10 of those reels.
Design an antenna for about 33-35 ohms, get more gain as a result, match it to
75 ohms at the antenna end with a quarter wavelength of 50 ohm cable and
transform the other end of the hardline into 50 ohms in the shack with a
twelfth wave matching transformer. I haven’t done that in many years (until
yesterday) but if I remember correctly, for .66 vf coax it is a length of 50
and 75 ohm coax in series that are 22.5” each (10m), 30” each (15m), 45” each
(20m) and 90” each (40m), etc. More gain and no SWR loss by having a 1.5-1
mismatch even if using a multiple of a half wavelength - all for free! My
experience is that you can get the better part of a half dB more gain with the
same boom length and sometimes eliminate a close spaced (to DE) element whose
main purpose was to achieve 50 ohms.
Thanks again - Stan, K5GO
> On Oct 5, 2024, at 1:17 PM, Jim W7RY <jimw7ry@gmail.com> wrote:
> Jeff
> Thanks for the memory jarring! I agree that this is what he has. The jacket
> is really hard and thick and not easy to get off.
>
> I had forgotten all about this old stuff. I pulled some of this stuff that
> was being used for a 2.4 GHz microwave shot when I was in Spokane. The
> removal was due to a 2.4 GHz rebanding project when the Wireless (cell)
> companies bought the 2.4 GHz spectrum from county and state agencies and
> moved them on 6, 10 and 18 GHz.
>
> You MAY be able to find some connectors. I would start with eBay. I
> distinctly remember what they look like now.
>
> 73, Jim W7RY
>
>
> On 10/5/2024 10:36 AM, Jeff DePolo wrote:
>>>> Copper clad aluminum, rings not spiral, OD of outer conductor is 1”. OD of
>>>> inner is 3/8”. Outer conductor is copper. I think you are on right track.
>>>> Measurements were all done with a steel tape measure as best I could.
>> After I responded I realized I might have an old Cablewave catalog with
>> specs for that cable in it, and sure 'nuff, I found one. Here are specs:
>>
>> FLC78-50J
>> Center OD: 0.357"
>> Outer ID: 0.850"
>> OuterOD: 0.990"
>> Jacket OD: 1.124"
>> VF: 88%
>>
>> Connector part numbers:
>> 738828 Type N male
>> 738829 Type N female
>> 738833 UHF male
>> 738832 UHF female
>> 738831 7/8" flange
>>
>> Let me know if you want me to look for connectors, or if you want a pic of
>> the catalog page. 73.
>>
>> --- Jeff WN3A
>>
>>
>>
>> _______________________________________________
>>
>>
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>
> --
> Thanks and 73, Jim W7RY
>
> _______________________________________________
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