----- Original Message -----
From: "Roger (sub1)" <sub1@rogerhalstead.com>
To: <amps@contesting.com>
Sent: Tuesday, April 05, 2011 7:08 PM
Subject: Re: [Amps] Alpha vs Henry
> On 4/4/2011 10:44 PM, Bill, W6WRT wrote:
>> ORIGINAL MESSAGE:
>>
>> On Mon, 04 Apr 2011 15:17:23 -0400, "Roger (sub1)"
>> <sub1@rogerhalstead.com> wrote:
>>
>>> , a true 1500 watt
>>> amp needs to be capable of nearly twice that to hold together.
>> REPLY:
>>
>> That doesn't make sense. If it can't "hold together" at 1500 watts, it
>> is not a "true" 1500 watt amp.
>
> And if that is the case there are a lot of amps being sold that either
> don't make sense, or are using false advertising.
> Do 4 811As running 800 watts make sense? How about 8877s with anemic
> power supplies that will hit 1500 pep in casual conversation, but won't
> last through a contest? How about a pair of 3-500s running 1500 watts
> from an amp you can carry under one arm? It'll run the legal limit, but
> not for long on digital or contesting. The 8877 and 3-500 examples are
> legal limit amps, but they won't do it all modes key down or even SSB in
> contesting.
>
> So I stick with the above statement. If you want it to hold up
> contesting, or any other mode using a high duty cycle then it needs to
> be able to do almost twice that ICAS.
>
> 73
>
> Roger (K8RI)
Another reason a heavy duty tube makes sense is operator error
survivability.
While protection circuits are supposed to save fragile tubes such as the
3CX800 and 8877 its not 100% guaranteed.We have also seen how well overated
tubes such as the Svetlana 4CX800A which is really just a mil surplus
rebranded 600W GU-74B wear out when pushed.
OTOH with a 3CX3000A7 for example you can use it for a dummy load and it
will survive that 3AM wrong antenna OOOPS in a contest or chasing a
DXpedition. With 3KV and 100W drive it will last near forever, easily run
legal 24/7 in any mode and be one of the cleanest tubes on the band when
driven by a Class A exciter.
Trying to do that with 3-500's in an AL-82 is just asking for a meltdown as
that amp is already on the edge of an IED event as are any of the AL-1200's.
Carl
KM1H
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