[CQ-Contest] Multi 2 locking device, TriPlexers and BPF

Jozef Urban, OM7ZZ om7zz at stonline.sk
Wed Jan 11 03:49:46 EST 2017

Good note John.
It depends on topology and purpose of use. If dual switch is used in lab or 
in the in-band setups (both radios operate on the same band), every dB 
matters. However, when switch is used in real world SO2R setups, where each 
radio operates on different band and RF topology uses classic order: TRX - 
BPF - PA - SWITCH - ANT, isolation between antennas sets the bar, what is in 
general much worse than isolation between radio ports on almost any 
available dual switch, even with resonant antennas located several wl apart. 
Switch is probably the last thing to blame for possible interferences.

** K9YC
You are spreading false and misleading information again! Intentionally?
Typical values of SWR and insertion loss are typical values, considering 
variations in manufacturing process and parts. These variations are low and 
typical values serve to make a picture what to expect from the switch.
Isolations have no typical values, isolation between radio ports depends on 
frequency AND on to which antenna port is each radio port connected to. This 
applies to every dual switch from every manufacturer. Therefore we state 
isolation between ports as a range from worst to best values, separately for 
various frequencies. There is nothing 6-10dB worse than claimed values.

Jozef OM7ZZ

> The 4O3A units have impressive specs but I wondering how important the 
> extra
> 20+dB is. I have never observed an isolation issue with my Array Solutions
> SixPak.
> John KK9A
> To: cq-contest at contesting.com
> Subject: Re: [CQ-Contest] Multi 2 locking device, TriPlexers and BPF
> From: Jim Brown <k9yc at audiosystemsgroup.com>
> Reply-to: k9yc at arrl.net
> Date: Tue, 10 Jan 2017 14:28:45 -0800
> On Tue,1/10/2017 8:23 AM, W0MU Mike Fatchett wrote:
> Is there an "easy" way to improve the port Isolation in the WX0B six pack?
> The only way I know of is replacement. I had one here, replaced it with
> 4O3A's 6x2, which was about 20 dB better (measuring both units on the
> bench). Not long after that, 4O3A introduced the new 8x2, and I replaced 
> the
> 6X2 with it. The 8x2 is more than 20 dB better than the 6x2, making it 45 
> dB
> better than the WX0B unit. Isolation is 100 dB, +/- 3-4 dB, depending on
> which band and which output.
> Several years ago, I tried to get specs on the Microham unit. What I got,
> eventually, was rather hard to read plots that showed that the BEST case
> isolation of the 6x2 was quoted in the data sheet as "typical", and that
> other ports were significantly worse (6-10 dB). I asked for a unit to
> measure (to give them the benefit of the doubt), but W4TV insisted that I
> buy one.
> Bottom line -- the 4O3A 8x2 is the best I know of. It's very well built, 
> the
> control interface is close to being universal, and the guys in CO who
> distribute it are great to deal with.
> I've NOT given any attention to weatherproofing, because my switching is 
> all
> done in the shack. My bandswitching is being done by the band decoders in 
> my
> 5B4AGN TXBPF filter sets.
> 73, Jim K9YC

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