[Johnson] Viking II

Sun, 04 May 2003 02:00:06 +0000

Just got my Viking II, a heck of a deal for 40 bucks.  (Considering I paid 80 
bucks for it and the accompanying SX130.)  Here are comments/questions. I'm 
sure some of them have been addressed before, but I scanned the archives back 
to 2000 without finding the answers. 

The rig is clean enough inside (blew out a few cobwebs) and the front panel is 
OK, but not great.  

1.  Seems R13 is open.  I will do as someone suggested and tap across it (have 
done that on other rigs years ago with good success) until and if I find a 
replacement.  But the question is, is this a really common failure in the 
Viking II?  I briefly had one of these things back in 1958, and had no trouble 
with it at all in the short period of time I owned it.  

I cooked it for a while, (the guy who sold it to me cooked it for ten hours at 
50 VAC, so mine was just a bit of "refrying!")  then tried it out and found 
plate current hit 300 ma instantly, so suspected bias supply.  Checked and 
found bias voltage is at minus 55 VDC, not minus 75.  I suspect the bias supply 
caps need replacing.    No smoke, no transformer oils, no overheated 
components, so guess it is going to be relatively easy to get back on the air. 

But this led me to check the R30 pot in the clamp tube circuit.  Turning the 
pot did vary the screen voltage, but it still was around 300 VDC  and the 
lowest the plate current went was 280 ma.  Appears, though, the 6AQ5 is working 
(though I'll probably replace it.) 

2. I've seen this on some other list - is there a way to do black krinkle?!  
While the case on this rig is fairly good, the top is heavily scuffed and I'd 
like to refinish it.  Without the krinkle, I'd just sand it down and repaint 
with dull black enamel.   Any comments? 

3.  Rig was modified for PTT, but not the approved Johnson circuit.  Someone 
changed the mic jack to a stereo jack and put in a PTT relay and power supply. 
 No other mods in the rig I have found.  

So my questions are regarding the resistor R13, and the paint. 

And I noticed in the archives someone said that the shunt resistor was also 50 
watts and it isn't.  It's a ten watt.  

Any other things I should be on guard for?  Comments are welcome!

73
Ed
W5HTW
http://w5htw.home.att.net/index.html