it could be a cap or something starting to go soft in the 40 meter area, I 
wouldn't worry about it unless you can't get full output.
----- Original Message ----- 
From: "colin McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 14, 2010 4:26 PM
Subject: Re: HeathKit SB-220 HF Amp tune up strangeness


> perhaps the law of diminishing returns?
> the amp may be only able to accept a certain drive input before the power
> tubes max out?
> not sure why this issue is only happening on 40M, but if you have to 
> reduce
> drive level to 65 watts to get 1K out, i'm not sure what the issue is
> really.
> just a characteristic of the amp I would say.
> If there was anything going on with the controls, it would be evident on
> other bands as well.
> going above the minimum drive level for the power output you want, or the
> max power of the amp will create big distortion.
> you'll sound like those good old boys on 27.025
> the thing is, even though it's a question, and a bit of a pain to have to
> tweek a bit, if you can get your desired max power output on 40M, with
> minimal drive, then just go with it.  I think a bigger issue would be if 
> you
> couldn't obtain max power output or something like that.
> 73
> Colin, V A6BKX
> ----- Original Message ----- 
> From: "Michael Ryan" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, September 14, 2010 9:06 AM
> Subject: HeathKit SB-220 HF Amp tune up strangeness
>
>
>> Hi all:=20
>>
>> I use an LDG Electronics TW-1 to manually tune my antennas and HeathKit =
>> SB-220 HF Amp.=20
>> My tune up procedure varies on 40M then on the rest of the bands. What =
>> is actually happening is, my TW-1's pitch, in the continuous tone mode, =
>> doesn't max out on 40M. When it does, the results are as follows:=20
>> 100 =3D 837 and when I reduce my drive, the power increases.=20
>> Its quite common to see 65W =3D 950.=20
>> In order to achieve 100 =3D 950 to 1KW, CW, I have to advance my plate =
>> and load controls short of Max, according to my TW-1.=20
>> What can account for this? Could my plate control be damaged and I'm =
>> actually advancing the control too far, possibly out of the 40M range?  =
>> I'd like it on par with the rest of the bands, Max pitch =3Dmax power =
>> out.=20
>>
>> 73:=20
>>
>> Michael DE VO1RYN=20