Gonset G-50

[WB4YVO]

Wonder why its different.. Mine seems to have more Grid current in Xtal mode  Maybe that's why..

Mine only loads to about 5 in plate position both Xtal and VFO..

Mine is rock solid no drift..

Skip

[KD1SH]

    I'm thinking the slow drift in power output must be heat related - the change takes place over a span of 30 seconds or so.  Something intermittent like cold solder or a cracked carbon-comp would be all herky-jerky spastic, while this is slow as molasses.

[PA0NVD]

Hi Skip
Fine to hear that all your wrk had good results, congrats!!!
Bill, doe the grid current and anode current also drift? 

[KD1SH]

    Haven't checked grid and plate currents at the oscillator yet, but at the PA they do show a slight change, in sync with the drift in power output.  The plate voltage at the 6146 drops with increasing power output and rises with decreasing power output, so that appears to be effect rather than cause.

[PA0NVD]

The anode voltage rises probably due to the decrease in anode current. See is the grid current also goes down when the power goes down. If it does, the problem should be the driver or oscillator stage. If not, check the G2 voltage. If stable, put a 10 000 pF ceramic from cathode to ground. May be the original cap is weak.

[WA1LGQ]

Concerning adding the push-pull transformer, what might be the impedance that is needed, or maybe it doesn't matter that much. I'm not sure how impedance should be calculated in that configuration.
Thanks...........Larry

[KD1SH]

 Hi, Larry,
   There are people here far more knowledgeable than my humble self, but my take is that since a Heising configuration - center tapped or otherwise - doesn't offer any impedance transformation between the modulator and the plate circuit, it's not something we'd have to worry about with this mod.  The Hammond 1645 that I'm going to be using for my G-50 has a 5K ohm primary, center tapped, so you'd have 2.5K on either side of the tap.  The secondary has taps for 4, 8, and 16 ohms, so it'll match your speaker.
    As a side note, at the recent Sussex hamfest I picked up a nice Clegg 99'er, and my friend picked up beautiful little Utica 650.  At the time I didn't know much about the workings of either rig, but a check of the schematics revealed that both rigs use the very same modulation scheme we're talking about using in our Gonset mod: a center tapped Heising choke.  I'm in the midst of a two-part vacation, so I haven't had time to play with my 99'er, but I'm looking forward to finding out how that modulation scheme sounds, and I really can't wait to hear my friend's Utica 650 on the air - that is one sweet looking little rig.