[ARC5] [Vintage-Military-RADAR] Re: A Cable Question

[J. Forster]

> John,
>
> I take it that RG-58/58A would look too skinny at 0.195"?

Partly looks, but more that the cable clamp will not go that small.
Serving the shield with a couple layers of #20 solid might work, but I'd
prefer to do it the way it was designed to be done.

> Looking
> through my cable charts the closest thing I see to 0.380"d would be
> RG-7 at 0.370"; 95 ohms and an old type probably very hard to find.
> Then there's RG-21A at 0.332"( but listed as a High Attenuation type),
> RG-42 at 0.342" (but gray and 79 0hms),  and RG-115 at 0.375" (but
> with a fiberglass jacket, not likely to be black).  RG-212 at 0.332"
> and 50 ohms wold fill the bill (double shielded type).  Don't see much
> after that.

That was pretty much my conclusion. There is a void between about 0.250"
and 0.400"

> Now, at the frequencies and with the very short cable lengths we seem
> to be talking about here the characteristic impedance of the line
> would not be important -- whatever Z appears at one of the cable will
> be reflected with negligible change to the other end.

The signal level can be made high, and it's only 2 MHz RF pulses anyway.

> I have some 75
> ohm cable I picked up in the U.K. years ago that is about 0.3125" OD
> and would be glad to donate 6 ft.or so with a PL-259 on one end.  The
> stuff does have a solid center conductor but the 93 should be able to
> accommodate this.

That would be wonderful. It sounds like it should work just fine. I'll
drop you a note off-list.

I still don't understand how they expected to make this work in WW II
however.

Thanks very much,

-John

==================

> Dennis D.  W7QHO
> Glendale, CA
>
> *************
> On Jul 27, 2011, at 4:54 PM, J. Forster wrote:
>
>> OK, this is involved:
>>
>> I'm working on a LORAN-A receiver for a Museum Ship and the antenna
>> connector is an Amphenol Type 93. This is an early WW II aardvaark,
>> used
>> in only a few places AFAIK. Thanks to a generous list member, I now
>> have
>> the proper connector in hand.
>>
>> However, the connector will not take standard RG-8 or RG-214 cable.
>> Their
>> OD is to big.
>>
>> Assembly instructions from another list member calls out Navy Type
>> CASSF-50-1 cable.
>>
>> Furthermore Google finds in "(1954) AN 16-30ARC5-2 Handbook
>> Maintenance
>> Instructions AN/ARC-5" that this cable is used to connect a VHF
>> ARC-5 to
>> the antanna and crosses it to RG-8/U.
>>
>> However, a check of current catalog of this cable specifies an OD of
>> 0.405
>> nominal, which will not fit.
>>
>> Apparently, the OD of RG-8 has changed over time. I think cable of OD
>> <0.380" will work. The center conductor needs to be stranded.
>>
>> So, does anybody know where I can get a few (6?) feet of the stuff,
>> even
>> more preferably with an PL-259 on one end? I'd buy a roll of maybe
>> 100' if
>> there is a source.
>>
>> Thanks,
>>
>> -John
>>
>> ================
>>
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