Final Tube question

[Bill Coleman]

On May 25, 2006, at 4:57 PM, TChesek at Epix.Net wrote:

>  Are there technical reasons, other than power output, to match  
> these or doesn't it matter? I haven't tried it but was also  
> wondering what would happen if I ran a HW/SB-100/101 or HW-12/22/32  
> with only 1 output tube. Seems like this is basic but I just began  
> to wonder when looking to possibly buy replacements tubes for a  
> Singlebander that I am attempting to repair.

In 1976, my Novice rig was an SB-401. Since Novices at the time were  
restricted to 75 watts input, I pulled one of the final tubes and ran  
it at about 60-70 watts in. Since the rig was designed for 90 watts  
in on each tube, I figured this was OK.

Of course, with one bottle the output impedance was all wrong and I'm  
sure this messed with the loaded Q of the output network -- but it  
did work, and I used this configuration for a couple of months until  
I found out that the FCC had changed the rules and Novices were now  
permitted to run 200 watts PEP. At that point I put the other tube  
back in, re-neutralized the finals and never looked back.

So, it can be done.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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