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Subject:
Re: Heathkit SB-220 HF Amp output
From:
Colin McDonald <[log in to unmask]>
Reply To:
Colin McDonald <[log in to unmask]>
Date:
Fri, 14 Aug 2009 14:12:11 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (57 lines) 
class AB2?
hmmm, never heard of that one...but i thought nearly all RF amps ran in 
class B only?
since they don't use a preamp because they are driven from the 100 watt 
transmitter?
If an sb220 can be run in class AB, then if you are getting 1200 out at that 
point it could be modified to put out a whole lot more then that running 
class B only.
at any rate, what is class AB2?

73
Colin, V A6BKX
----- Original Message ----- 
From: "pat gormley" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 14, 2009 2:08 PM
Subject: Re: Heathkit SB-220 HF Amp output


> that's about right since you're running in class ab2 which sounds like
> everything is running nominally. 73- pat kk3f
> ----- Original Message ----- 
> From: "Michael Ryan" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, August 14, 2009 3:21 PM
> Subject: Heathkit SB-220 HF Amp output
>
>
>> Hi all:
>>
>> I recently picked up a Heathkit SB-220. After taken the steps
>> necessary to bring it up slowly, the amp was idal for 15 years, here
>> is my results.
>> I use an LDG Electronics TW-1 Watt Meter to tune and here are the steps.
>> 1. Placing the meter in tone mode, key down in CW, Adjusting the Tune
>> control on the amp to find the highest pitch possible. That's how you
>> find the plate setting.
>> 2. Key down in CW, with tone mode, adjusting the load control to find
>> the highest pitch possible. With 10 watts from my exciter, I see about
>> 180W.
>> 3. With the amp in stand by, I increase my exciter to 100, re_ingage
>> the Amp in CW, adjusting the load control for yet more pitch.
>> The result is approximately 1000W. Note the amp is in CW/Tune and each
>> adjustment on the controls take about 10 seconds.
>> When I reduce my exciter's drive to 60W, I see 800W with the amp still
>> in CW/Tune. When I switch the amp to SSB, I only get another 200W.
>> Total output, 1KW on SSB with 60w of exciter drive. With 100W drive, I
>> won't see no more than 1300.
>> Is this normal? I don't think the tubes are bad because the amp powers
>> up to spec in CW/Tune.
>> 100W drive =1000.
>>
>> TNX all & 73:
>>
>> Michael De VO1RYN
>>

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