Most of the heath kits, including the DX60 had a drive adjustment that 
was critical.

You had a capacitor to peak, then you adjusted the drive for a 
particular current value with a pot.

Same goes for the DX100, Viking 2, Valiant, etc.

The 6146 is a tough tube, but it has a fragile grid, so a little too 
much drive, and you buy a new final. I've been there and done that.

I had forgotten how simple the T60, and its clone the HT40 were to 
tune.

Johnson made another interesting transmitter called the Viking 
Challenger. I never operated one, so I'm not sure about the tuning. It 
used a low level clamp tube modulation scheme, and a pair of 6DQ5 
tubes in the final. Some people have modified them for screen 
modulation, and made them sound quite good with about 25 watts of 
carrier out on AM.

I'd love to find an AM transmitter that tunes like the old Heath HW 12 
series. The grid drive was set internally, the loading capacitor was 
fixed, and all you had to adjust was the plate capacitor of the final 
for highest output, aka highest pitch.

I'm resurrecting a Gonset G76. I've had it on the air, but it's got to 
go back to my friend for a little more modulation cleanup.

I have an old Science for the Blind comparitor oscillator on the 
meter, but can tune it as Kevin described by using the TW1.

When I get it running right, I should have about 40 watts of carrier 
output on AM.

The Gonset G76 is a single 6DQ5 plate modulated by a pair of the same 
tubes.

It's a transmitter, and a duel conversion receiver in the same box. 
The coverage is claimed to be 80 through 6 meters, but nobody I know 
has ever gotten a G76 to do anything other than blow up on 6 meters.

It's a neat old rig, about the size of a DX60, but uses an external 
power supply.


Mike Duke, K5XU
American Council of Blind Radio Amateurs