[Amps] Soft 572b's

[Kent Landis]

Hello All

I have a Dentron Clipperton L with the original ( and very soft)  
572b's in it. I have found that the filament voltage at the tube  
sockets is 7.49 volts!! I have remedied that problem as well as  
removing the CB mods and restoring all to original. With the tubes in  
it the amp will now make about 300-350 watts on all bands and the  
power supply is in fine shape.

My question is that the amp tunes up fine on all frequencies 
( including WARC) up to about 26 MHZ but will not amplify 10 meter  
frequencies at all. The amp does have the 10 meter mod and I have  
changed the coil tap back to the 10 meter position. Is it possible  
that the soft tubes might be the culprit? I see tha 572b's are only  
rated to 30 mhz so 10 meters is right near max frequency/
Any help will be greatly appreciated. I just wanted to get this  
resolved before re-tubing.
Tnx es 73
Kent
N8ZRD