[TenTec] SB220-Tubes and QSK

[Gary Hoffman]

Very logical and practical.  The ideas have merit, regardless of picking
nits about fractions of dB's.  I would be happy too.

Gary

----- Original Message ----- 
From: "N4YG" <n4yg at comcast.net>
To: <tentec at contesting.com>
Sent: Thursday, November 01, 2007 1:36 PM
Subject: Re: [TenTec] SB220-Tubes and QSK


> First, I would like to say that I am delighted to have set off such a
> nice discussion.
>
> Second, getting back to the SB-220, even with only a fraction of a dB
> gain in output power, I am still exceptionally pleased with the
> installation. The increase in output power which I said was 20% is
> actually more like 50% depending on how you calculate it. I was
> getting 600-700 watts out on 40m and now I am getting about a KW.
> Some might say that is an increases of over 50%.
>
> Third, power output is not the primary reason that I am so pleased. I
> had seen the reviews saying that the SB-220 ran cooler after
> installing the new tubes. Reading this casually, I sort of
> disregarded it. But when I observed it for myself, I was impressed.
> It is beginnng to make sense. The input power was about the same
> before the new tubes. If the amp is 60% efficient now, it must be
> dissipating about 670 watts. If the additional power I am now getting
> out was previously being dissipated, the amp was dissipating 300 -400
> watts more before or about a KW. That explains why it is running so
> much cooler. If all this logic is sound, the efficiency with the old
> tubes was only about 40%. Now that is a good reason to buy new tubes
> even though only a dB or two power gain is realized.
>
> Joe
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>