Zetagi V2 antenna switcher.

Silly question of the day ..... The Zetagi V2 antenna switcher.....When used with one antenna and two radios....It will obviously TX and RX on the selected radio side, but will it sill RX on the second radio, or does the big red switch have control over both TX and RX?

I would like to have both radios on at once, TX on one of them but monitor the other, 1 Multimode and the other my UK40 muppet.  is this possible with the Zetagi V2 or do I need something different?

Thanks in advance.

Matt

I wondered the same a while back.
But then thought it may damage one of the radios. Although as you say it's switched between one or the other. Since it's manufactured for two antenna's to one radio I didn't want to put anything to chance.

Have you connected two radios through it and transmitted ?


There is this for two radios to one antenna rather than one radio. which is more expensive.

https://www.kcb.co.uk/contents/en-uk/p1779_Zetagi_SW2_Automatic_Antenna_Switch.html


I wouldn't of thought two at the same time would be a good idea, it would I imagine at least throw the SWR through the roof and at worst the set transmitting blow the other set.

I'm interested in the replies though

Hi Matt,

The Zetagi V2 is simply a single pole double throw (SPDT) switch in a box so won't do what you ask.

I just had a shifty on the old t'internet and there's a picture on this forum of the internals so you can see for yourself :-

https://www.forumradioamatori.it/forum/index.php?topic=8055.0

It simply connects one side or the other.


(I had written a lot of stuff about isolation problems and such but thought better of it. Let's just say you're going to run into a whole heap of trouble trying to monitor and transmit at the same time even with different radios. Don't let F.O.M.O or fear-of-missing-out cause you problems.....if someone calls on the 19 Muppets but you're busying yourself on the free-bands then so be it. )

Ah, just noticed Nige's response, the Zetagi SW2 is a more refined piece of kit but you're still only going to be able to use one radio at a time. As he mentions on simpler switch units you could be transmitting into a short or open circuit (SWR protection should handle that) but equally transmit from one radio into the other rendering it deaf-as-a-door-post from thereafter!! (More expensive manual units ground the other connections providing isolation for receiver circuitry.)

If you really want to know about the issues of running transmitters and receivers at the same time you only need a shifty-look at Ham radio repeater systems. Huge cavity filters and big frequency separations are the order of the day!

There was me trying to keep this short too. Again, F.O.M.O. so keep it simple with one radio at a time.  


All the best,
Victor

2 radios 1 to tx and 1 for rx = 1 blown front end.
With hf and vhf/uhf you might be ok.

i have a v4 model of those and it seems to work ok

Same sort of kit there Lionel just with a couple of more single pole double throw (SPDT) switches.
(Three switches in a box. ) No grounding of unused ports, poor isolation, probably insertion losses too. 

There's a good reason why decent coaxial switches cost big bucks.

what do you suggest Victor swap the ant coax manually when using different radio's ?

Personally, I would never do this...but if you want to, the way to check it is safe is as follows:

Get the isolation figure for the switch you want to use, at the frequency you're using (i.e. 27MHz), then get the max power either radio will generate, and do the math to see what "input" power is going to go into the antenna of the other radio.  If it is more than the radio can handle, don't do it.

You might be safe with a 4w or 12w CB, assuming the isolation figure stated isn't picked out of the air by the manufacturer, so better still to measure what is going into the other port.

Better again, just don't risk it. 

For the sake of a bit of further information on such issues as this I'll post the following couple of links.

Here's a great video from Alan - W2AEW :-




An example of a homebrew coaxial switch which also references the above work is from Peter - VK6YSF :-

https://vk6ysf.com/rf_switch_20220626.htm


You'll see that every effort has been made to check and/or measure the required isolation characteristics before utilising such devices and even then with an assumed safety margin. Note that you can even damage a receiver whilst it is powered OFF if too much RF power is placed upon the antenna input!

Unfortunately it is hard to find such specifications on cheaper pieces of equipment so the only real way to be sure is to actually measure the characteristics yourself. Trying to find out the isolation characteristic of your transceiver/rig would be much harder if testing it for yourself as it'd be akin to testing a match....one strike, yep that works, but never to be repeated.

With the radio interest there are a lot of 'black-box' products where you don't actually know what's going on inside them and a lot of 'box-pushers' who happily sell you such items but then you're on your own from thereafter. Due diligence is the order of the day.

Hearsay can also be a dangerous thing such as "my mate uses such-and-such" as often they're unaware of their actions or the consequences. I've seen/repaired more than one radio in my day with receiver front ends 'blown' replacing fiddly PIN diodes and other front-end semiconductors. Often the user is unaware but might stretch as far as "Oh, really? I thought it was a little deaf on receive".


Back to the original poster Hawk657, Matt - 

Even if you successfully isolate both transceivers (or even go as far as placing separate antennas on them) you'll still swamp the one on receive whilst transmitting on the other especially on the same band of frequencies. When using different bands such as with Amateur Radio you can still face problems and you only have to look at a Ham field day where much spacing between participants or extra band-pass filters are the order of the day.


Remember, all my 'waffle' ever given here on CT is not in some vain attempt of uplifting my apparent intelligence or so called radio expertise, but in my best efforts to help out where I can.

I'll warn you of minefields even if you don't understand what that "Achtung! Minen!" sign means, but I certainly won't tell you to put your fingers in your ears and stomp forwards hoping for the best.


73
Victor

Thank you all so much for the amazing detail given above.  Brilliant and very kind.  

cheers.