[Drake] passband tuning alignment

[Larry Taft]

Use the S meter for peaking the tuning screws.  The Rad Shack meter is too 
low an impedance to accurately set the AGC voltage.  You'll just have to 
play with the AGC/S meter adjustments after you get the tuning peaked.  Or 
borrow a VTVM or modern digital high Z input meter.  An oscilloscope with a 
10X probe would also work.

You should be able to set the S meter "zero" and then turn the RF gain tab 
all the way CCW and have the S meter go full scale or close to it.  If not 
then you have a weak tube or tubes as they are part of a bridge circuit for 
the S meter.

If you get hung up with the AGC ask again and I'll come up with a better or 
at least different way.

73, Larry  K2LT
drakerepair.com


At 08:47 PM 4/2/02 -0500, you wrote:

>Hi
>  I have a question here.
>  I have the later model R4A (11 tubes ). What I have been trying to do
>is   probably  stupid to try but no other way. I have the copy of the
>service  manual (lost the original) and where it says  on the  procedure
>there to get a certain max  agc voltage, this is where I'm not sure my
>voltmeter is  doing what it should.
>   I have no vtvm for tube  equipment ,instead I have to rely on an old
>rat shack multimeter .  Model 22-216,It's at least analog so I can see a
>peak.
>I have  5 settings  for  voltage.
>3,12,60,300,and 1000.
>Which one of these is the best for capturing that all elusive max agc
>voltage they  have in the  passband alignment section where you are
>turning the  4 tiny   little pins in the back of the  passband tuner box
>there to get max agc voltage?
>It says to tune to 3800 and have  rig at calibrate. Turn  the 4 screws
>till  I attain max voltage.
>I know that I have to  probably retube this   but I thought least
>getting the passband in alignment was a start .
>Thanks
>Chris
>
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