[TowerTalk] Antenna switch isolation?

[Pete Smith]

Another trick to consider is arranging the relays so that there are two 
sets of open contacts between ports.

BTW, it is quite amazing how little relay capacity is really required 
for a legal limit antenna switchbox - Top Ten, for example, uses a NAiS 
relay that costs about $2 a pop.  I have tried to break these running 
really high SWRs at 1200 watts - without success.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com


On 6/5/2010 8:02 AM, n8de at thepoint.net wrote:
> Martin,
> With careful orientation of the relays and grounding of unused
> contacts, 60db of isolation is possible.
>
> The amount of 'internal coupling' between relays is the major
> difficulty when trying to get very good isolation.
>
> 73
> Don
> N8DE
>
> Quoting Martin Sole<msole at loxinfo.co.th>:
>
>    
>> How much isolation should I be aiming for in a remote relay switch box. I
>> have some 30A rated relays that look as if they will handle a fair amount of
>> power. I can see only about 40dB of isolation across the open contact. I
>> don't need it to go above 30MHz and 2kW handling should be fine. Antenna
>> connections will be all low impedance. So 1kw into the common port will give
>> me about 10mW at the open port, enough?
>>
>>
>>
>> Martin, HS0ZED
>>
>>
>>
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