[ARC5] Considering GO-9 Transmitter Power Options.

[howard holden]

It goes against conventional wisdom, but here’s how I run my GO-9 (over ten years now, with thousands of contacts, and many thousands of hours using the SAME tubes I started with). Mine had the power supply completely gutted except for the controls and meters, and was poorly remade with a TV power transformer, and a commercial regulated supply which puts out 350VDC. I rebuilt it my way, with a huskier HV transformer and rectifier board assembly (1400VDC no load, 1300V loaded to 110 mA), and separate filament transformers. Kept the regulated supply. I used the existing plate current meter, the power level switch to switch between two secondary voltages on the HV side, and the existing rheostat to vary the primary voltage to the 803 filament trans, as was done in the GO supply.

Whoever redid it originally had permanently grounded the contact from R302 which grounded the grid resistors for the oscillator and buffer. While I could have keyed it via that contact, I opted to try keying the center tap of the 837 filament trans through its 1000 ohm resistor, which happens to work just fine. I know keying the VFO is a supposed “no-no”, but chirp is almost non-existent, and stability is exceptional for an 80 year old transmitter. As originally wired with the original power supply, the 803 is keyed only by the high voltage primary trans through K201, which is non-existent in mine, and in Dave’s, as I noted from his photos. There’s no bias supply in the GO-9. I found with mine the 803 draws about 50 mA idling, meaning with my HV supply it’s dissipating about 70 watts. That may sound terrible but it’s not, so I did not add a bias supply. I leave my GO lit up for days at a time, mostly because my operating opportunities often come at the spur of the moment, and I could kill my available time waiting for the oscillator to stabilize. Original tubes. 100 honest watts out 80 and 40, dropping to about 80 on 30 meters, and 70 on 20 and 17 meters. 1400V on the plate, 350V on the osc and buffer. No need to try and kill it with the full 2000V. The power gain isn’t worth it. YMMV but I’m not going to fix what ain’t broke….

73, Howie WB2AWQ

On 9/2/2019 7:13 AM, J Mcvey via ARC5 wrote:
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