Re: L7 input coil ajustment
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Howard:
I'll add two comments to David's instructions for adjusting the input tuning on the L-7
1)? Check out the L-4B instructions.? They got that correct and it's the same procedure.
2)? While I would not personally recommend adjusting the input tuning with high voltage applied...for safety reasons...but?IF you choose to do so, keep in mind you would also have to defeat the HV interlock to do this with the lid off....which IS necessary to reach the coils.
I recently did some work on an L-4B for a ham in Surrey, BC.? I did the input tuning on his amp after undoing some "magic nichrorme" mods and adding in some more modern ones (Electronic Specialties).? Note the input tuning is very broad, though perhaps due to aging of the caps, I did notice a slight improvement on some bands.? As such, I am not in any hurry to adjust the input tuning on my own amps, unless perhaps the tubes get changed at some point.
Hey guys, I'm going to be doing a input coil adjustment on my L7 amp. Eimac tubes are getting very soft and I'm replacing them with RF Parts matched pair.
I've done this before and i'm very aware of safety procedures. It's been awhile.
I just want to clarify a few things before I start. Procedure (F) I take it that the plate control should also be in the centre of the band I am adjusting , this is not mentioned in procedure. Also when increasing exciter output to achieve a .400 amp. reading on the grid meter, procedure (I) is this correct because my other L7 manual said plate meter.
Lastly when tuning the plate control for dip in plate current, procedure (J) is it a greatest dip possible or just a slight dip in plate current??
Thanks for any input you can provide. Howard VE7IGA
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