[Johnson] Some more Valiant and SSB adapter questions

[Roy Morgan]

At 07:36 PM 12/24/03 -0500, Dave and Sharon Maples wrote:
>1. I'm getting ready to replace the 18K resistor in the VFO case.  ... SHORT
>leads.  ... the best way to do either of these,

Dave,

I don't understand the need for SHORT leads on that resistor. it supplies 
B+ to the oscillator/voltage regulator tube.  Why short?  I suggest you 
punch a hole in the chassis for the tube, make it look real professional, 
and mount the resistor underneath on standoffs.  Figure the dissipation of 
the resistor and buy a resistor of at least four times that value.  Do NOT 
use a 2 watt unit.

>  .. Any other components I should
>either check or replace while I am in there?

Yes: Any resistor in sight.  Apply the tiny-est amount of DeOxit or ProGold 
to the capacitor wiping contact(s) and a tiny drop of oil or bit of grease 
to the end bearing(s) of the cap.  Likewise, treat the switch in the same way.

>2. The meter resistors in the Valiant are 0.202 ohm nichrome wire thingies 
>...I can
>purchase 0.200 ohm, 1% resistors off-the-shelf.  That will make the meter
>between 0% and 2% off.  Does anyone see any reason NOT to just use the
>off-the-shelf 1% resistors?

That will work just fine.  Leave about 3/4 inch leads on then new shunts to 
make up the missing two milli-ohms!

>3.  SSB adapter.    RG-62/U coax.   correct length?

Sorry, don't know. Is there a picture in any old QST or Handbook you can 
guess from?

>4. There is a modification suggested by some to remove the driver
>transformer and redo the 12AU7 as a phase splitter.  Is this really worth
>the effort?  What are the downsides?

Yes it is really worth it, especially after your driver transformer quits 
due to being undersized and old, and after you get report after report that 
- "Hey, you must be using a Valiant with that stingy, pinched, terrible 
sounding audio!!"

The downsides are that you have changed your radio but it will sound 
better.  If you are doing a quick job, you drill at least one new hole in 
your chassis. If you take the time, you make a little strip of aluminum to 
mount the new transformer on that can be bolted in with the old hole 
spacing (drill and tap the strip to accept just-short-enough machine 
screws, use countersunk flat head screws at the ends to fasten the new 
longer transformer.)  Any replacement transformer the same size is too 
small. Don't use it.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
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