Ron, You've gotten good advice so far:
- Get the manual from BAMA - Build & use the 6 dB swamping attenuator described therein. More advice from me: - Don't try to drive it until you test the aux coupling capacitors for leakage. - Make sure that your T-bolt correctly biases the tubes Reason for the attenuator is it allows you to tune the T-bolt combo at full output, then "whack" the drive by 6 dB to allow for the modulation envelope, just by turning one switch. Easy easy easy. Note that the design impedance of the attenuator must be (and is) 350 ohms to match the drive impedance of the Thunderbolt. You will be running it Class AB1, of course, so no grid current will be drawn to screw up the drive impedance. There were two different versions of the Thunderbolt; the earlier one used 4-400As, the later one used PL-172s. There were some bias circuit changes to accommodate the PL-172s, so if you have a later amp with 4-400As in it, you need to un-do the changes. The manual on BAMA is the early version; I have an orig manual for the later version which I can copy for you if you need it. There were one or two other changes made to the later version that are practically mandatory for the early version. Write me for the details. That's all I have time for at the moment (it's 6 am and I need to be off to work). Will write more later. regards, Mahlon - K4OQ > From: "Ron Samchuk" <[EMAIL PROTECTED]> > To: <[email protected]> > Date: Sun, 6 Apr 2003 19:24:26 -0500 > Subject: [AMRadio] re: Ranger driving Thunderbolt > Reply-To: [email protected] > > Greetings again to all the AM crowd. Well, I did get the Johnson = > Thunderbolt.... looks great. It only needs about 20 watts drive. What = > is the easiest way to reduce the power of my Ranger to properly drive = > the Thunderbolt? Thanks from Ron VE4SR
