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Two HF and one VHFwith a triplexer?

Aug 8th 2011, 12:06

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
A member asks:

I own an Icom 746 (non-Pro) for my base transceiver. The 746 has two HF 160 - 6 meter antenna ports and one 2-meter vhf port. I would like to find a triplexer which would allow me to use one feed line between the transceiver and three antennas, a Cushcraft R-8 40-6 meter vertical, a horizontal loop with an SGC-237 antenna coupler for 160 - 6 meters, and a Diamond 2-meter vertical antenna. Do you know of a triplexer with two 160 - 6 meter ports and one 2-meter port? Alternatively, if no triplexer exists for this configuration, what other options do I have with this transceiver and antenna collection?

A triplexer routes signals simultaneously to three ports based on frequency—thus, the outputs of all three ports must be different frequency ranges.

What you may want is a pair of diplexers to separate the 2M and HF/6M signals at either end of the single feedline. You will need a remote antenna switch to switch between the two multiband antennas.

Zack Lau W1VT
ARRL Senior Lab Engineer



Sep 2nd 2013, 22:44

RecycledElectrons

Joined: Jun 2nd 2011, 04:57
Total Topics: 0
Total Posts: 0
I have a similar problem. I recently ordered a Yaesu FT-8900R. It has a single 239 (259) connection for the antenna. It does 10m, 6m, 2m, and 70cm, which is everything I want to run mobile.

I thought it would be easy: I have one antenna mount for each frequency.

The problem is quadplexing the antenna.

I think can get a triplexer that will divide it into 70cm, 2m, and everything else.
Diamond MX2000: http://www.gigaparts.com/store.php?action=profile&sku=ZDM-MX2000
Comet CFX-514: http://www.gigaparts.com/store.php?action=profile&sku=ZCM-CFX-514
So my first question is: would one of these work, with the HF output tied into a manual switch for 6M and 10M? My Yaesu puts out 50 watts PEP, max.

The problem is: Using a manual switch seems like a good way to destroy my radio's final output stage if I have it set to high power and key into the wrong antenna. Is this a problem with the Yaesu FT-8900R, or is it sufficiently protected to prevent this?

A triplexer that would split off 10M, 6M, and VHF/UHF would work better for me, as there are lots of 2M/70CM combination antennas, but I can not find such a triplexer.

Is it possible to cascade a dupexer after a triplexer? I seem to remember that this is a bad idea, but I don't know why.

Is there such a thing as a 10M/6M duplexer?
Sep 3rd 2013, 00:55

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0


http://www.diamondantenna.net/mx610.html

Diamond makes a duplexer to split 10 and 6 meters.

Yes, you can cascade a duplexer after a triplexer.

Zack Lau W1VT
ARRLSenior Lab Engineer
Sep 3rd 2013, 05:34

RecycledElectrons

Joined: Jun 2nd 2011, 04:57
Total Topics: 0
Total Posts: 0
Thank You for Your kind reply! That's a great product,

but I now realize: There are about a dozen antennas out there with "8900" in their names, that are quad-band antennas. They are compromises. They do not get all the 6M band and all the 10M band, but they seem to claim to work without an antenna tuner. They run $80 to $160 each, and will break like any antenna.

I am going to resist the temptation to run 4 separate antenna mounts (for now) and get an antenna that claims to work with a bit of tuning. (My MFJ antenna tuner should make tuning easy.)
Nov 30th 2013, 03:03

KM3F

Joined: Mar 6th 2008, 13:50
Total Topics: 0
Total Posts: 0
I know this is an old thread but the subject needs more input.
First there is a multiband antenna on the market now.
Secondly the uses of di or triplexers is not the end all because they do not perform as well as is thought.
Everybody takes them for granted they work without issue.
A check with SWR and power meters on each band between the radio and the plexer will show a significant loss in pass through power and SWR may be high enough to cause transceiver power fold back such that nothing works very well..
Bottom line is not to use them unless you accept the results.
The other answer is to build them custom tuned to each band of use using low loss coaxial designs and adjustable tuned traps.
The ones available are cheap low grade broad band designs for the cost.
Good luck.

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