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From: koning@koning.enet.dec.com (Paul Koning)
Newsgroups: sci.electronics,rec.radio.amateur.misc
Subject: Re: Andrew heliax question
Message-ID: <20583@shlump.nac.dec.com>
Date: 27 Feb 91 18:20:55 GMT
References: <1991Feb26.223024.9457@ariel.unm.edu>
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Reply-To: koning@koning.enet.dec.com
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Organization: Digital Equipment Co., distributed systems architecture
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|>Hi.  We have obtained a few hundred feet of Andrew Heliax coaxial
|>cable, and would like to use it with our OSCAR station.  However,
|>we know nothing about heliax...
|>
|>1. The cable is FSJ1-50 Heliax, 84147 Andrew, 51470 AO1P.  Is this
|>   good for anything on the ham bands?
|>
|>2. Connectors: where can we get a couple, and are they really as
|>   expensive as I've heard?
|>...
|>Ollie N6LTJ

That's not the type you most commonly see, but it certainly should
be useable.  According to my Andrew catalog (1986 edition), FSJ1-50
is 50 ohm "superflexible" 1/4 inch Heliax.  Superflexible means
that it's more deeply corrugated than the standard type, making it
more flexible.  That's by Heliax standards; by ordinary coax standards
I suspect it's still pretty stiff.  Compared to the "ordinary" cable
of that size (FHJ1-50) it has essentially the same power rating but
5-10% higher loss.  Some electrical parameters:

Peak power: 5 kW max
Averate power: 5 kW at 1 MHz, 1 kW at 100 MHz, 0.3 kW at 1000 MHz.
Attenuation (dB/100 ft): 0.18 at 1 MHz, 1.85 at 100 MHz, 6.59 at 1000 MHz.
Max frequency: 19 GHz

As for connectors: there have been numerous writeups in QST and the like
on homemade connectors (UHF typically) for aluminum CATV hardline.
Those sort of designs should work here too, with the added plus that
the copper shield can be soldered.  (There's a risk of melting the
dielectric, though.)  How well such things perform is anyone's guess.
Certainly you'd have to keep them out of the rain.

If you want official connectors, Andrew should be able/willing to
sell them direct, or look in the back of QST at some of the tower
dealers.  (Texas Towers?  I remember seeing Heliax connectors mentioned
there, though for the larger size cables.)  Yes, they are expensive.
The 1986 price list shows $6.00 for the UHF (41SP), $9.00 for N plug (41SW),
$7.50 for BNC plug (40622).  Those numbers look strange, considering
the UHF plug for the non-superflexible cable (41P) goes for $32.50.
But who knows...give them a call.  (708) 349-5950.

Enjoy!

	73, paul, ni1d