Mike Tubby wrote:
>On 02/06/2011 03:31, Gary K9GS wrote:
>> A friend recently purchased a 2M amp. This amp does not have any T/R
>> switching but does have 12V DC available. Can anyone recommend a
>> suitable relay to use for the input and output? Output power of the amp
>> is 700-800W.
>>
>>
>
>I'd suggest a Tohtsu CX-600N on the output and something smaller on the
>input, or, alternatively a CX-800N which is double throw.
>
>Check out Ebay HenryRadio are setting some CX-800N relays and RF Parts
>appear to have the CX-600 on offer.
>
>There are a lot more 24/26/28V relays around cheap than there are with
>12V coils - the latter are a premium. The difference is sufficient that
>all the relays on my home station and contest stations are 24V.
>
This circuit may help. It delivers a 24V 'kick' from a normal 12V supply
rail. The relay voltage then falls back to 12V, which is enough to hold
in most 24V relays quite comfortably.
An alternative use for the same circuit is to speed up a 12V open-frame
or coaxial relay to avoid RF hot-switching.
<http://www.ifwtech.co.uk/g3sek/in-prac/best-of.htm#speedup>
For full details, click on the "April 2002" link.
The two MOSFETs provide a low-current 12V switching interface for any
transceiver. NPN bipolar transistors could also be used with appropriate
resistor changes.
--
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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