[BC] Re: Early Rigid Coaxial line 2

[Richard Fry]

>> In 1981 I rebuilt a 12 Bay RCA Batwing TV Antenna,

>The lines were phasing lines, and were cut to a specific length
> for each bay.
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Small comment about this.  If it was an RCA Superturnstile, and it had no 
tilt/fill, then those semi-flex feedlines out of the power dividers all 
were the same physical/electrical length.  The length was chosen so that if 
one or more feedstraps was/were open at the radiator connection, the SWR 
defect that appeared would lie outside the active TV channel.

If was a GE Batwing, they used different lengths for each bay level, with 
the electrical lengths feeding the same relative phase at all levels 
(absent beam tilt/null fill).  But if the feedstraps opened at the batwing 
connection, that would throw a sizable mismatch into the active channel, 
which would cause noticeable ghosting in the received TV picture.

Two different design philosophies there, and both had some benefits and 
drawbacks.

RF (who as an RCA employee aided/abetted in the initial assembly and 
testing of quite a few new RCA Superturnstiles, and the 
re-harnessing/testing of many more.)