Tim,
That's not quite what the manual says. To quote the manual exactly:
"The "phone" position removes the short and applies screen voltage to the 807's from the high voltage bleeder-divider tap. Sections of the high voltage primary "plate" switch are interconnected in the keying circuit so that the keying circuit is opened whenever the "plate" is off and the "cw-phone" switch is in the "phone" position. This eliminates oscillator interference while listening to a station operating on the same frequency as the Viking II."
They are talking about two different parts of the switching circuit. When they talk about the switch removing the short and applies screen voltage to the 807's, they are talking about the short across the secondary of the mod tranny in the CW position and the opening of that short and the application of voltage to the 807 modulator screens as accomplished by SW3A and SW3B.
There also is a set of contacts on SW3 (C) that diverts the cathode circuit of the oscillator from the keying jack to a set of contacts on SW2.
SW2 is a double pole switch that applies AC to the primary of the HV tranny but in the AM mode grounds the 6AU6 cathode for transmit.
Johnny JN .. the bleeder that they reference in the text is R13, a 20K power resistor with a tap and voltage fron that tap is what supplies the modulator screens when in the AM mode. In the CW mode the screens receive no voltage, thus turning them off. R13 is the HV bleeder.
As you said in your last thread .. you are hearing the Viking II oscillator when you are in receive. I can only guess as to what the problem may be but it is obvious that you are not opening the ground supplied by the contacts of SW2 when you go into receive. Either the switch is bad OR it might be that you have put in some switching arrangement that causes you to leave SW2 in the transmit position while using this "other" switch to turn off the HV primary.
? Only you can answer that one.
There are other problems that you have told us about. Like not reading grid current on the meter. That is a separate problem but may be tied to a bad bias supply. The readings that you get on AM show little or no output and then slowly come up.
You need first to make sure the bias supply is OK. Replace V11 a 6AL5, the bias rectifier and then check the bias voltage. It should be -75 volts on the output side of the 10 hy filter choke L3. If it has not been done already, I would replace C12.
After that is done you must do the procedure on page 11 of the 1953 version of the manual. It talks about setting the bias control R30 properly. This is the clamp tube adjustment and would definitely affect the transmitter as you describe.
So Tim:
1) How are you switching between transmit and receive? Describe exactly what you are doing.
2) Again, have you changed the rectifier tubes and checked the supply voltages and what are they? I am speaking of all supply voltages including the bias supply. Are they all withing tolerance and are the stable?
--Larry W8ER
