VIKER 2 MOD. RESTING CURRENT..

[ve6pg]

..hi from tim...i cant get at my viking2 manual, just now...but i have a question....where/how is there an adjustment fer the resting current on the modulators?...my meter indicates it is rather high...130mils..

..suggestions?...

tnx...

..sk..

[W3NP]

Tim,
With the rig loaded to 230ma plate current, adjust the slider on R13 for 70-80 ma of static modulator current. R13 is a 20K power resistor with a slide adjustment.

The manual suggests that you make the actual adjustment with the power off!!! 

[KB3DKS]

Tim,
   You can pull down a good copy of the manual from the BAMA mirror site for reference and follow the procedure as Dave said above.

    The manual specified alignment is only good if the 807s are a normal bias range and the plate and bias supply is as noted in the manual chart. I added 1 ohm 1%cathode resistors to check for match/ballance.

  Check for correct bias voltage then proceed.
Be carefull moving the slider on the big 20K resistor. Don't overtighten. I use a fixed 25K now.

  You might have to use a Variac to set the DC voltage parameters to text values if your AC line voltage is odd.

 Regulating the bias voltage would probably be a good idea as I have noticed that the final grid current has a small interaction with the modulator bias.

  I just went over my VK II, solid stated all supplies and replaced the 807s with Sylvania 6CA7s, connected the screens to the LV supply and added a bias adjust pot close to the new sockets.
 These 6CA7s can handle 400V screen.


Bill, KB3DKS in 1 Land

[WA1GFZ]

The first time I adjusted the slider on my V2-CDC the resistor failed so yanked it and built a Zener shunt regulator for the screen supply then added a zener to the CT of the driver transformer to zener regulate the 807 bias.

[ve6pg]

..thanks guys...got her going, as far as the mod. resting current...
..now gonna post another question...

..tim..

..sk..