Bill is correct, the weak point in this amp is the transformer. I blew mine up
on RTTY twice and no longer have it. The trick is to replace the transformer
with a Peter Dahl transformer if you can find one at a reasonable price.
I ran mine at 500 watts on RTTY until the transformer went out.
73, Don AA5AU
>________________________________
> From: "Bill, W6WRT" <dezrat1242@yahoo.com>
>To: RTTY Reflector <rtty@contesting.com>
>Sent: Monday, September 24, 2012 11:46 AM
>Subject: Re: [RTTY] Heathkit SB-1000 On RTTY
>
>IGINAL MESSAGE:
>On Mon, 24 Sep 2012 11:07:56 -0400, NZ4O wrote:
>
>>I have a Heathkit SB-1000 amplifier with the single 3-500Z. The manual for
>>the Heathkit SB-1000 says a maximum plate current of 400 mA for CW and 550
>>mA on SSB.
>>
>>What would be a safe maximum plate current for RTTY operation, which is
>>obviously 100% duty cycle like AM operation?
>
>REPLY:
>I ran an SB-1000 on RTTY for several years. The weak point in that amp is not
>the tube or tank circuit, it's the power transformer. At 1kW RF output during
>RTTY contesting you will soon start to smell the transformer overheating.
>Not a good smell.
>
>Hold it down to 600 watts RF output and you can run it all day long.
>
>73, Bill W6WRT
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>
>
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