[Heathkit] How about the SB-220?

[Carl]

Woops, I forgot to specify the Drake L-4

Sorry

Carl

----- Original Message ----- 
From: "Jim Shorney" <jshorney at inebraska.com>
To: <heathkit at mailman.qth.net>
Sent: Sunday, August 23, 2009 11:58 AM
Subject: Re: [Heathkit] How about the SB-220?


> >Which goes against what the original designer recently said on another
>>forum.The original way had a 2-3dB IMD improvement which is identical to
>>what Ive measured as far back as the early 80's with the SB-220.
>
> I'm not sure exactly what part of the below that you are commenting on 
> here,
> Carl.
>
> 73
>
> -Jim
>
>
>
> On Sun, 23 Aug 2009 11:29:12 -0400, Carl wrote:
>
>>
>>----- Original Message ----- 
>>From: "Jim Shorney" <jshorney at inebraska.com>
>>To: <heathkit at mailman.qth.net>
>>Sent: Saturday, August 22, 2009 3:37 PM
>>Subject: Re: [Heathkit] How about the SB-220?
>>
>>
>>> On Sat, 22 Aug 2009 12:32:27 -0700, Paul Baldock wrote:
>>>
>>>>I'm not sure this is true. I have rebuilt two SB221's and grounded
>>>>the grids directly. This does give more gain and allows you to turn
>>>>the driver rig down. Turning the driver down from 100W to 90W on a
>>>>12V rig greatly improves its IMD and more than the negative feed back
>>>>that the amp "may" have with the Heathkit design.
>>>>
>>>>I have had no instability problems and the output is very clean. I'm
>>>>not aware of any modern 2 X 3-500Z amps that use the Heathkit method,
>>>>they all directly ground the grids.
>>>
>>>
>>> After reading all the pros and cons of this idea, I came to the 
>>> conclusion
>>> that
>>> the reasons for directly grounding the grids made more sense (to me) 
>>> than
>>> the
>>> alternatives. I grounded the grids in my L-7 and it has been running 
>>> great
>>> that
>>> way. FWIW.
>>
>>Which goes against what the original designer recently said on another
>>forum.The original way had a 2-3dB IMD improvement which is identical to
>>what Ive measured as far back as the early 80's with the SB-220.
>>
>>Carl
>>KM1H
>>
>>
>>>
>>> 73
>>>
>>> -Jim
>>>
>>>
>>> --
>>> Ham Radio NU0C
>>> Lincoln, Nebraska, U.S.S.A.
>>> TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A,
>>> GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!
>>>
>>> "Give a man a URL, and he will learn for an hour; teach him to Google, 
>>> and
>>> he will learn for a lifetime."
>>>
>>> HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
>>> http://radiojim.exofire.net
>>> http://incolor.inetnebr.com/jshorney
>>> http://www.nebraskaghosts.org
>>>
>>>
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>
>
> --
> Ham Radio NU0C
> Lincoln, Nebraska, U.S.S.A.
> TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, 
> GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!
>
> "Give a man a URL, and he will learn for an hour; teach him to Google, and 
> he will learn for a lifetime."
>
> HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
> http://radiojim.exofire.net
> http://incolor.inetnebr.com/jshorney
> http://www.nebraskaghosts.org
>
>
> ______________________________________________________________
> Heathkit mailing list
> Home: http://mailman.qth.net/mailman/listinfo/heathkit
> Help: http://mailman.qth.net/mmfaq.htm
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>
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> Please help support this email list: http://www.qsl.net/donate.html