The poster's point was that you cannot do that as there would be no isolation
between antennas and the RX would be toast. The duplexer adds isolation, maybe
enough without filters, maybe not, but quite a bit.
73, Drew K3PA
-----Original Message-----
From: TowerTalk <[email protected]> On Behalf Of
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Sent: Tuesday, November 18, 2025 11:00
To: [email protected]
Subject: TowerTalk Digest, Vol 275, Issue 21
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Today's Topics:
1. Re: Looking for a HP 80/40 Duplexer ([email protected])
----------------------------------------------------------------------
Message: 1
Date: Tue, 18 Nov 2025 11:47:21 -0500
From: <[email protected]>
To: <[email protected]>
Subject: Re: [TowerTalk] Looking for a HP 80/40 Duplexer
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
W8FN?s QRZ pages listed his 40m/80m antenna as a fan dipole, not a trap dipole.
I am sure most people on this towertalk list can figure out how to separate a
fan dipole into two antennas with two feedlines. If a diplexer is a better
option than go for it, I was just suggesting another option.
John KK9A
From: Jack Brindle <[email protected]>
Sent: Tuesday, November 18, 2025 9:42 AM
To: [email protected]
Cc: [email protected]
Subject: Re: [TowerTalk] Looking for a HP 80/40 Duplexer
Two feed lines on one antenna is definitely not a solution. The only isolation
would be whatever loss is in the feed lines. Basically you would be putting
high power directly into the *other* receiver. I doubt that is survivable.
Pavel has a page that specifically discusses his 80/40 diplexer. It is
definitely worth a look. That is at:
https://va6am.com/2017/01/01/4080-band-diplexer/
73,
Jack, W6FB
On Nov 17, 2025, at 10:04?PM, [email protected] <mailto:[email protected]> wrote:
As others have stated I am sure that VA6AM can make a 80/40 duplexer for you
however the easiest approach would be to just run another feedline to your fan
dipole.
John KK9A
Randy Farmer w8fn wrote:
I'm investigating upgrading my station from its present 500W capability to
1500W. I've located sources for most of the up-rated bandpass filters and other
hardware required for the project, but can't seem to find a source for a
duplexer to split a 80-40 dipole for SO2R use. I'm presently using one of the
Low Band Systems 500W 80/40/20 triplexers for this function. LBS apparently
makes a 1500W 80/40 duplexer, but it appears the LBS stuff is no longer
available in the USA. Does anyone have or know of a suitable 1500W unit? I do
NOT need it to be rated for 100% duty cycle since I'm only interested in CW and
occasional SSB use, but it needs to hold up under contest conditions with a
full power amplifier.
4O3A makes a nice 20/15/10 triplexer, but they don't have any high power
80/40 units. Antennas-Amplifiers (distributed by DX Engineering) makes nice HP
bandpass filters, but not a triplexer or duplexer. VA6AM (also distributed by
DX Engineering) doesn't have any high power devices.
73...
Randy, W8FN
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