Yeah, that's why I cautioned Gary about using CATV splitters at 160m. Seems
that he has enough reserve gain with his Beverage and K3, that he could
certainly tolerate the loss of a 50 ohm resistive splitter. The design of
those is simple and he surely should be able to tolerate the 3.5 dB or so of
splitter loss.
73,
Charlie, K4OTV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Carl
Sent: Friday, March 14, 2014 10:41 AM
To: Charlie Cunningham; garyk...@wi.rr.com; 'Topband Mailing List'
Subject: Re: Topband: Passive Receive Antenna Splitter
All the TV splitters Ive taken apart are pure autotransformers with poor
isolation. A VNA will show them deterioating and doing very little at 160M.
It is simple enough to wind transformers for a splitter using 1/2 type 43
toroids. See this link that gives an excellent discussion and also shows the
cheap way of doing it and the better way. Guess what is used in consumer
grade CATV versions.
http://www.minicircuits.com/app/AN10-006.pdf
Both versions have been in handbooks for decades and I first started using
them with Beverages in the mid 80's. Ive also used them as combiners and
connecting various combinations of 2 Beverages with some very beneficial
performance at times. Port to port isolation was very important to me.
There are also several other on line versions, good and bad, if you do a
Goggle for how to make a 2 way 50 ohm splitter
Carl
KM1H
- Original Message -
From: Charlie Cunningham charlie-cunning...@nc.rr.com
To: garyk...@wi.rr.com; 'Topband Mailing List' topband@contesting.com
Sent: Thursday, March 13, 2014 9:41 PM
Subject: Re: Topband: Passive Receive Antenna Splitter
One word of caution, Gary, if the CATV splitter is a transformer type,
rather than resistive it may of have enough low-frequency response for 160
m! Check around with RS and your local electronics stores for 50 ohm
2-way
splitters. Those are generally resistive and have frequency response from
DC
up to a GHz or so. Some of the TV stuff is transformer coupled.
73,
Charlie, K4OTV
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Gary
K9GS
Sent: Thursday, March 13, 2014 9:14 PM
To: Topband Mailing List
Subject: Topband: Passive Receive Antenna Splitter
Can anyone point me to a design for a splitter for sharing a Beverage
antenna between two receivers? This is for Field Day so these are not
optimized Beverages by any means.
Just want to allow the 80/40M stations to share antennas. Nothing fancy.
My thoughts are to just use a CATV 2-Way splitter at the output of the
Beverage matching transformer and run separate feed-lines to each radio.
I'm pretty sure these things work down to 1 MHz but have not measured
them.
I can use the pre-amp in the radio (K3) to compensate for the loss.
Thoughts?
--
73,
Gary K9GS
Greater Milwaukee DX Association: http://www.gmdxa.org Society of Midwest
Contesters: http://www.w9smc.com
CW Ops #1032 http://www.cwops.org
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