[TowerTalk] Mixing different coaxs

[ROBERT WANDERER]

I mix RG8X and 9913 and on HF have never noticed a problem. The issues
you raise would be of concern if you were phasing (e.g. 4-Square, 4 over 4 for
20, etc.) and then for physical lengths (and you can avoid that by using a
specific type coax past the splitter). Having swept cable in cable tv industry,
the capacitance, velocity factor etc do not stay constant even on the same
reel of cable (measurement called structural return loss or SRL; in essence
you're looking for worst case contribution of these anomalies frequency wise).

I'd use 213 over 8. I'd also use Times Microwave LMR400DB (direct burial)
over 9913. The LMR has a hydroscopic coating on the shield to prevent water
migration if there should be any ingress; this is a major problem with 9913 as is
the structural weakness due to its construction (air dielectric).

73, 
Bob AA0CY

----------
From:  JCCR/TV, Inc.[SMTP:jccrtv@jccrtv.com]
Sent:  Sunday, January 18, 1998 9:20 PM
To:  towertalk@contesting.com
Subject:  [TowerTalk] Mixing different coaxs

If this is a stupid question, please forgive me in advance. I have 9913
going from the shack out to the tower site. I don't want to run the 9913 up
a crank up because it's probably too rigid and would be damaged from the
lowering/raising motion. Can I use RG-213 or 8 from the antennas down the
tower and connect it to the existing 9913 that goes up to the shack? I've
never mixed coax before, hence my question: Is there a problem with velocity
factor/or capacitance/or signal loss mixing coax?

Jim KS1A



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