Discussion in '"Boat Anchor" & Classic Equipment' started by KD5NDQ, Apr 14, 2019.
Is your SG switch on or off ?
It appears there is IP meter indications which eliminates the rear panel "SG" switch being in the
If the SG switch were to be in the OFF position then there would be zero IP meter indication in any
mode transmit. In the OFF position the final tube screen voltage would be "negative" resulting in
any electrons to be repelled back towards the cathode.
If the SG switch were to be in the ON position then there would IP meter indication in any mode
transmit. In the ON position the final tube screen voltage is positive allowing electron flow from
the cathode to the screens and plates.
At what position is the CAR control knob set? If it's at 10 o'clock with 75ma indicated on
the IP meter in CW mode transmit, rotate the CAR control clockwise in CW transmit to see if the
IP meter increases. Next rotate the PLATE control both CW and CCW, throughout its range.
Do you see a dip in IP meter indication? If not then I still suspect the band switch coupler
could be cracked or broken causing the final amplifier band switch wafer to not rotate to the
proper setting for the band selected, hence no dip in IP meter when rotating the PLATE knob.
Perform the "check" on the final amp band switch assembly to see if it moves exactly like
the long band switch shaft and RF Unit wafer switches rotate.
2 o'clock position
Makes no difference where I set CAR control knob.
I've kind of lost track of where you are in all of this, but is this correct?
- You get good ALC response when you peak the Drive control even with the Carrier control at 12 oclock or thereabouts?
- You get around 80 mA of plate current when keying the rig in SSB mode but not talking into the mic or having mic gain all the way down? (If so adjust the bias till that reads 60 mA per the manual)
- When you key in CW mode with the load control fully counter clockwise you see maybe 100 mA of plate current and you don't get a pronounced dip in the plate current with the Tune control?
- Advancing the Load control has little to no impact on plate current while keying the rig in CW mode?
Earlier in this thread I thought you had solid plate current as in 200mA or so when keying in CW mode but if you really can't get good plate current regardless of Load and Tune settings (and SG switch is on as you've posted) then I'd strongly suspect either the final tubes themselves or the cathode and screen resistors. Those cathode resistors are also the plate current meter shunts so if they drift high in value (they often do) then your plate current readings are all out of whack. Make sure the combo of cathode resistors reads 5 ohms (4 resistors, 20 ohms each in parallel in the TS-830 and TS-530). If they read much higher than that, replace them. Check the screen resistors while you're in there as they can also get cooked and screw up finals power.
If all the resistors on the finals board check out then I'd strongly suspect final tubes assuming the point above about not getting more than 80 to 100 mA or so of plate current while keying the rig in CW is correct.
If you can get a lot of current but no RF output and no Tune dip as I originally thought then we're back to band switch wafer output relay, coupling cap or associated wiring.
The band switch coupler is not cracked and when in the "10" setting the rotor wiper on the S22 switch shows it to be in the 1 o'clock position which as I understand is the correct one. Switching to different bands the switch makes solid stops & clicks; it takes a fair amount of torque to change the band setting. While the knob has a little bit of "give" in it without changing bands I see no movement in the rotor wiper on the S22 switch at all when I observe this "give".
Yes no dip in plate current, but only roughly 60mA of current in CW mode. In TUNE mode it shows roughly 90mA.
Yeah, I'd test the cathode and screen resistors, replace them if necessary and order up a new set of tubes.