[Elecraft] linear amp shutdown (was ALC)

[David Cutter]

Geoff

With so many combinations of rig and amplifier a 'standard' would be good, 
(the Collins ALC started it all I understand) but in its absence each 
operator needs to make provision for their own station protection.

With the advent of solid state amplifiers there was a chance to make a new 
standard to help us all, perhaps someone knows if this was taken up .  It 
would be good to know how folks have covered themselves with various 
rig/amplifier combinations and  I wonder how the Elecraft linears will do 
this.  I see the SPE linear has 3 stages of protection for instance: SIMPLE 
= audible alarm, SERIOUS = switch to standby and FATAL = complete shutdown, 
but these do not shutdown the driving transmitter as far as I can see. 
After all, running barefoot is better than nothing in a contest, so, 
shutting down the transmitter is not always desirable.

David
G3UNA


----- Original Message ----- 
From: "Geoffrey Mackenzie-Kennedy" <gm4esd at btinternet.com>
To: "David Cutter" <d.cutter at ntlworld.com>
Cc: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Sent: Tuesday, December 04, 2007 12:46 PM
Subject: Re: [Elecraft] linear amp shutdown (was ALC)


> From: David Cutter G3UNA
>
>> I take your point entirely which is why I said
>>
>> "ALC is an analog signal for gradually reducing drive, which
>> might not be appropriate for shutdown."
>>
>> Shutdown for me is for protection against gross overload and for this 
>> another signal might be more appropriate.  Since many users do not 
>> connect ALC, some other signal for protection should/could be provided. 
>> The problem yet again is that users might still ignore what the 
>> manufacturer offers, so, the amplifier must protect itself.
>
> -------------------------------------------------------------------
>
> David,
>
> It has always been my understanding that normal and good practice is for a 
> shutdown system to actually *shutdown* the entire transmitter affected in 
> the event of gross overload / failure, e.g. *abnormal* VSWR, cooling 
> system failure etc.  A system which protects the amplifier only could 
> still result in damage to the exciter / driver under some circumstances of 
> gross overload / failure, for example when using my K2/100 a while back 
> during some contest wind toppled a large pine across the antenna in use, 
> the KAT100 sparkled and both the KPA100 and K2 were damaged. My K2/100 is 
> now protected by the total shutdown system used with my other rigs, 
> something that I should have done before ever using the K2/100 at this 
> location.
>
> I take your point that the amplifier should be able to protect itself  if 
> people ignore what is offered.
>
> 73,
> Geoff
> GM4ESD
>
> .
>
>
>
>