John
KM4KMU wrote: No single cable had a VSWR over 1.10 with most being 1.05
or less. With the CF-4160 inserted the VSWR to the 440 antenna >jumped to
2.4 to 2.9 and the 144 was at 1.6 to 1.8 across the simplex frequencies.
That sounds like a failed component in the diplexer. I have run
back-to-back Comet tri-plexers on my 3 band omni stack for 6m-2m-70cm for
over 10 years with no standing wave issues with either 10W beacon or 50~100W
transceiver power levels. I did take the time to carefully waterproof the
triplexers.
Although a diplexer or triplex may have .4 to .7 dB insertion loss, it
would seem you could easily make that up with a single higher grade cable
(LMR600, etc.). Another advantage is the diplexer or triplexer provides
additional filtering. A triplexer is a low pass, band pass, high pass filter
arrangement and you get the additional filtering benefits on both receive
and transmit for each triplexer port. When you use a triplexer or diplexer
on each end of a single cable, the filtering performance is approximately
"dB additive" See below...
https://www.dropbox.com/s/8owsumh7yxa2zzs/2tripxr.jpg?dl=0
Reference: 2016 ARRL Handbook, Supplemental CDROM, CH13, VHF and UHF Beacons
WA3TTS
73, Mike wa3tts
----- Original Message -----
From: <vhfcontesting-request@contesting.com>
To: <vhfcontesting@contesting.com>
Sent: Sunday, July 10, 2016 12:00 PM
Subject: VHFcontesting Digest, Vol 163, Issue 8
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Today's Topics:
1. Coax Switch vs. Duplexer (Jarred Jackson)
2. Re: Coax Switch vs. Duplexer (Mark Spencer)
3. Re: Coax Switch vs. Duplexer (Floyd Rodgers)
4. Re: Coax Switch vs. Duplexer (nosigma@aol.com)
----------------------------------------------------------------------
Message: 1
Date: Sat, 9 Jul 2016 22:59:51 +0000
From: Jarred Jackson <Jarred.Jackson@hotmail.com>
To: "vhfcontesting@contesting.com" <vhfcontesting@contesting.com>
Subject: [VHFcontesting] Coax Switch vs. Duplexer
Message-ID:
<BLUPR11MB0081791683A194BA35A463719A3D0@BLUPR11MB0081.namprd11.prod.outlook.com>
Content-Type: text/plain; charset="iso-8859-1"
I have an IC-7000 with a common VHF/UHF output and switch between 2m and
70cm amplifiers/antennas using a Diamond CX-210A coax switch. I am
thinking of replacing the switch with a Comet CF-4160 duplexer that I have
had laying around unused. I would like one less thing to do when switching
between bands. It looks like there is 10dB less isolation (60 vs. 70 dB)
and about 0.1 dB additional loss by using the duplexer. The radio sends
the amplifiers 5W on 2m and around 28W on 70cm.
Any concerns / thoughts on making this change? It seems straightforward,
but I have had the same thought on other changes that haven't turned out
so well.
Thanks,
Jarred - KF2MR
------------------------------
Message: 2
Date: Sat, 9 Jul 2016 16:14:35 -0700
From: Mark Spencer <mark@alignedsolutions.com>
To: Jarred Jackson <Jarred.Jackson@hotmail.com>
Cc: "vhfcontesting@contesting.com" <vhfcontesting@contesting.com>
Subject: Re: [VHFcontesting] Coax Switch vs. Duplexer
Message-ID:
<8F05ADE0-ABBA-457C-B322-D9FE4C39B28B@alignedsolutions.com>
Content-Type: text/plain; charset=us-ascii
I've used a Comet CF 4160 for a similar purpose with an Icom 706 MkiiG.
I didn't experience any issues.
(The only caveat I'll mention is that I almost exclusively use double
shielded patch cords in my roving set up.)
73 Mark S
VE7AFZ
Sent from my iPhone
On Jul 9, 2016, at 3:59 PM, Jarred Jackson <Jarred.Jackson@hotmail.com>
wrote:
I have an IC-7000 with a common VHF/UHF output and switch between 2m and
70cm amplifiers/antennas using a Diamond CX-210A coax switch. I am
thinking of replacing the switch with a Comet CF-4160 duplexer that I
have had laying around unused. I would like one less thing to do when
switching between bands. It looks like there is 10dB less isolation (60
vs. 70 dB) and about 0.1 dB additional loss by using the duplexer. The
radio sends the amplifiers 5W on 2m and around 28W on 70cm.
Any concerns / thoughts on making this change? It seems straightforward,
but I have had the same thought on other changes that haven't turned out
so well.
Thanks,
Jarred - KF2MR
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VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
------------------------------
Message: 3
Date: Sat, 9 Jul 2016 18:52:02 -0500
From: Floyd Rodgers <kc5qbc@swbell.net>
To: Jarred Jackson <Jarred.Jackson@hotmail.com>,
"vhfcontesting@contesting.com" <vhfcontesting@contesting.com>
Subject: Re: [VHFcontesting] Coax Switch vs. Duplexer
Message-ID: <b0cfec0c-fb6a-f20e-270d-9a390a380ef5@swbell.net>
Content-Type: text/plain; charset=windows-1252; format=flowed
For field day I run an ft857 using a diamond mx72 duplexer to split
vhf/uhf to single band amps and recombine the signal with another mx72
which goes to a dual band beam. At home similar ft847 to single band
amps combined into 7/8 hardline feeding separate beams. I've never had
an issue running up to 150w. The pair of duplexers in this configuration
yields 120db of isolation
------------------------------
Message: 4
Date: Sat, 9 Jul 2016 22:28:40 -0400
From: nosigma@aol.com
To: Jarred.Jackson@hotmail.com, vhfcontesting@contesting.com
Subject: Re: [VHFcontesting] Coax Switch vs. Duplexer
Message-ID: <155d2a29eb9-7885-1f819@webprd-m61.mail.aol.com>
Content-Type: text/plain; charset=utf-8
The below relates to FM Simplex frequencies.
If this is just for casual conversation use the diplexer it makes life
very easy. If this is a weak signal contest set up go with the switch.
After the January VHF/UHF contest I put a lot of effort into minimizing
losses and getting VSWR, losses and reflected power as low as possible on
my set up. I was running Yagi's on 144 and 440 with an FT8800 (dual band
radio) single output. I was using the Comet CF-4160 to let me run a
single cable up the mast from the radio to the two Yagi's. No single
cable had a VSWR over 1.10 with most being 1.05 or less. With the CF-4160
inserted the VSWR to the 440 antenna jumped to 2.4 to 2.9 and the 144 was
at 1.6 to 1.8 across the simplex frequencies. Not a big deal at 144, a
horrible outcome for 70cm. I installed a coax switch (Alpha Delta) and
saw the VSWR at 440 drop to below 1.4 at 144 and below 1.6 at 440.
When I add start adding TE amplifiers,with integral pre amps, this summer
I may use a triplexer between the radio's and and the amps but the added
reflected power and insertion losses will be have no effect on output
power and minimal effect on received signal since they are between the
radio and the amps. I will never use a triplexer or diplexer between the
antenna and TX output or first stage RX amp again.
73
John
KM4KMU
-----Original Message-----
From: Jarred Jackson <Jarred.Jackson@hotmail.com>
To: vhfcontesting <vhfcontesting@contesting.com>
Sent: Sat, Jul 9, 2016 7:01 pm
Subject: [VHFcontesting] Coax Switch vs. Duplexer
I have an IC-7000 with a common VHF/UHF output and switch between 2m and
70cm amplifiers/antennas using a Diamond CX-210A coax switch. I am
thinking of replacing the switch with a Comet CF-4160 duplexer that I have
had laying around unused. I would like one less thing to do when switching
between bands. It looks like there is 10dB less isolation (60 vs. 70 dB)
and about 0.1 dB additional loss by using the duplexer. The radio sends
the amplifiers 5W on 2m and around 28W on 70cm.
Any concerns / thoughts on making this change? It seems straightforward,
but I have had the same thought on other changes that haven't turned out
so well.
Thanks,
Jarred - KF2MR
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VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
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End of VHFcontesting Digest, Vol 163, Issue 8
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