[TowerTalk] Stack-matching

[Joe Subich, W4TV]

Jim,

The question wasn't about a transfer switch ... it was about
a stacking switch that would allow the antennas to be fed to
separate rigs when not used as a stack.

73,

    ... Joe, W4TV

On 2022-07-19 8:16 PM, Lux, Jim wrote:
> On 7/19/22 4:26 PM, Lux, Jim wrote:
>> On 7/19/22 3:04 PM, Joe Subich, W4TV wrote:
>>>
>>>
>>> On 2022-07-19 4:34 PM, Lee Hiers wrote:
>>> >
>>>> Does anyone know of a commercial stack-matching box (for 2 antennas)
>>>> that will send the unselected antenna to another port?
>>> MicroHAM stack Switch would do that for two or three antennas. AFAIK,
>>> the product has been discontinued.
>>>
>>> I believe the Array Solutions Stack Match will do that *with* the
>>> optional external relay.  However, since I don't use those products
>>> I suggest contacting the manufacturer for details.
>>>
>>> 73,
>>>
>>>    ... Joe, W4TV
>>>
>>> On 2022-07-19 4:34 PM, Lee Hiers wrote:
>>>> Hi all...
>>>>
>>>> Does anyone know of a commercial stack-matching box (for 2 antennas) 
>>>> that
>>>> will send the unselected antenna to another port?  As in: I'm using the
>>>> high antenna on radio A, and that makes the low antenna available 
>>>> for use
>>>> on Radio B.  And vice-versa.
>>>>
>>>> I envision two antenna connections and a stack output and an 
>>>> alternative
>>>> output...something along those lines.
>>>>
>>>> I thought I'd seen a commercial product that did this, but I can't 
>>>> find it
>>>> now.  I'm sure something could be rigged up using external relays 
>>>> (and I'd
>>>> love to hear from anyone who's done that as well), but I would like to
>>>> evaluate other options.
>>>>
>>>> Thanks, 
>>
>>
>>
>> Some other things to think about are "port to port isolation" and 
>> "fail safe" .
>>
>> You want to structure the switch matrix (e.g. if using SPDT switches) 
>> so that the radios are always isolated from eachother.
>>
>>
>> If all you have is 2 antennas and 2 radios, what you want is a 
>> "transfer relay" or, in microwave parlance, a "baseball switch", or 
>> for DC motors, a "reversing switch".  It's a DPDT set up to swap paths.
>>
>> THey're available surplus for moderate powers (and, I suppose high 
>> powers), but they're designed so that you never inadvertently have 
>> output from Radio A going into Radio B.
> 
> 
> here's a fairly beefy vacuum transfer switch.. I can't find a data 
> sheet, but I believe it's rated for kilowatts.  what you'd also want to 
> know is the isolation.  60 dB isolation with a kW on one path would be 1 
> mW on the other path, which probably won't blow up your receiver.
> 
> https://mgs4u.com/product/rly-lc-01/
> 
> 
> fwiw the transco 700C70400 on the mgs4u website is only rated for 20W. 
> You see a lot of those and similar ones surplus.
> 
> here's a test report from 1972 (back when Deep Space Network was still 
> called Deep Space Instrumentation Facility) on a bunch of different models:
> 
> https://ipnpr.jpl.nasa.gov/progress_report2/XI/XIW.PDF
> 
> _______________________________________________
>