[AMRadio] valiant problems

[w5sum]

well I don't have all of my  notes right here in front of me but let me tell 
you what I can remember right off the top of my head.

#1, your doing the right t hing shotgunning all of the caps, regardless if 
they are paper bypasses, ceramic disks, or electrolytics. Thats an important 
first step.

Now.. look on your schematic at the output section. They use series/parallel 
silver mica's to come up with the output loading caps. These are notorious 
for going bad on you. If they don't just fail right off, th ey can do 
squirrely things to your output loading, cause rf spurs in area's where you 
don't want them, and, if they fail, can actually take out the rf choke that 
is in the B+ line and etc.   Those damn things are receiving silver mica's 
rated 500v each. Barely adequate, if that. Why Johnson did this I will never 
know.

One of the series/parallel combo's adds up to 330pf and one adds up to 150pf 
( I think ). Replace each of these with a SINGLE 3000V or 6000V transmitting 
mica. You can get them from Surplus Sales in Nebraska. They are not cheap, 
but what price for replacing a lot of other stuff that can be burned up if 
those originals fail?  You will have a small difficulty finding room for 
these big caps, but you can do it. I did.  Also, there is another little cap 
that is multi section in there, total capacitance is 1200pf. I have never had 
one fail but it could. Just look at it real good.

Okay.. the VFO.. its a bitch to get into BUT.. you want to pry it open and 
remove that bastard 18K 2 watt resistor. You want to add a small solder stip 
somewhere under the chassis, right beneath the VFO and tie a new 18K 5 watt
ceramic resistor, across the solder strip, with one end of the resistor 
soldered to the ground lug that attaches the solder strip to the chassis. 
Then run a wire from the other end of the new 18K resistor ( the end above 
ground ) to the point inside the VFO where the original resistor was hooked 
up.  That factory resistor is well known for failure and when it goes, it 
eats up all kinds of components in the VFO. Its well worth the trouble to 
move it out of there, plus, it takes some heat out of the VFO.

Tubes.   don't put 6146A's, B's or W's in your Valiant. It was designed 
around plane jane 6146's.   You can still get them. I have the name of a 
fellow at home somewhere, down in florida that will sell you amperex 6146's 
for a very good price, brand new in the boxes. The modulation section 
especially likes them, and the RF will be much easier to neutralize with 
these.

Examine the bandswitch real well, as well as the switch that switches 
capacitance in and out of the output loading. Look for carbon traces. If they 
are there, on the ceramic, scrub them off with a pencil eraser IF you can get 
to them. If not, get it off the best you can.

And WHILE you have the beast out of its cabinet, clean all switches and 
controls with De-Oxit.

after you get everthing changed out, neutralize the rig, and set the idling 
modulator current as per specs in the manual. 

DON'T PUT THE SCREWS BACK IN THE CABINET UNTIL YOU HAVE RUN IT A WEEK OR 
TWO.. LOL

man.. its a bitch to pry it out of that cabinet when all the screws are in 
it, and you can visually see fire inside ( this happened to me when a 
modulation transformer shorted to ground ).

Valianta are not operator freindly. I love them, they are good radio's but if 
you don't want to be working on a radio a lot.. a valiant is not a good rig 
to have. Its not as reliable as a Ranger.  But its a damned sight better than 
a DX100 or Apache LOL

good luck with your rig and holler at me if I can help in any way.

Ronnie

On Fri, 26 Sep 2003 13:35:16 -0500, Anthony W. DePrato wrote
> hi Ronnie:
> would love to get your ideals on the Valiant. got my caps ordered 
> today.. only $65.00 worth to replace all the eletro's and .005 
> disks. 40 of those . wanted to do it right when i put it on the 
> bench.. btw i may have another one next month.. if things work out. 
> 73 Tony wa4jqs 
> 
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The "AM" voice of Shreveport, Louisiana USA
formerly WN5AIA and WB5AIA
I got my Extra Class the old fashioned way... I earned it!