I don't know the particular antenna so I'm going by experience in
similar situations in offering this this thought: It seems to me
that you should be able to put the diodes between the antenna's
internal equivalent to a bias-T and and the D.C. supply line to the
pre-amp, out of the RF path.
Burt, K6OQK
At 05:00 AM 9/3/2009, [email protected] wrote
From: [email protected]
Subject: Re: [time-nuts] GPS Antenna Voltage-Dropping
To: [email protected]
In a message dated 03/09/2009 02:05:20 GMT Daylight Time,
[email protected] writes:
I bought a 3.6-V Trimble Bullet GPS antenna on ePay and wish to use it
with
my T-bolt. Rather than try to internally modify the T-bolt to provide a
3.6-V antenna feed, I decided to try to build an in-line dropping adapter.
I seriesed two Si diodes inside a 100 pf tubular ceramic capacitor and
installed the shrink-wrapped assembly inside a salvaged BNC-M to BNC-F
coaxial
assembly. Unfortunately the completed assembly exhibits about a 4-to-1
VSWR when terminated in a 50 ohm load. Has anyone else tackled this
challenge?
The 3.6-V Trimble antenna has less gain than the 5-V version which makes
my planned antenna rcable run on the edge even without the high VSWR..
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
[email protected]
K6OQK
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