[R-390] Best ballast tube resistor

[John KA1XC]

Bill,
those are all great mods you have there, only a matter of time before they
become basic restoration must-do's and are included in the FAQ site.

Another useful one is to drill a hole next to or just under the KC  tuning
knob so that the PTO end point can be adjusted from the front. Depending on
the radio type (A or non) you might need to bore through a gear or two for
extra clearance but they'll have plenty of metal left over and were over
designed anyway.
This way you can fine tune the PTO length every time you use the radio.

73, John



----- Original Message ----- 
From: "Bill Smith" <billsmith@ispwest.com>
To: <r-390@mailman.qth.net>
Sent: Tuesday, May 13, 2003 2:28 AM
Subject: Re: [R-390] Best ballast tube resistor


> That sounds like a great idea, Jim.  There are lots of tubes around, and
so
> what if they don't quite operate at the right voltage as long as they
> operate ok.  You can probably also eliminate drift by adjusting your
> control.  I might try that on mine.  I don't have any space left on the
> front panel, so think I'll use a screwdriver slot type and won't need a
> knob.  It should fit just below the Line Meter switch.
>
> I couldn't find a right meter for my set, so I used a larger meter.  It is
> easier to read anyway.  I had to carve a little out of the washer
underneath
> one of the handles, because the meter bezel bumped into it and
> unfortunately, the saw slipped when I was expanding the meter hole, so
there
> is a little "air" on that side of the meter, but I used larger sheet metal
> screws and one of them holds it down real good.
>
> I didn't like the on-off switch, so I drilled another hole right above the
> frequency readout and put in a toggle switch.  Also, the calibrator isn't
> very good, and my PTO isn't very linear anyway, so I drilled another hole
> just below the function switch and mounted a rotary switch with 100kHz,
> 10Khz and 1Khz positions.

<snip>