[Milsurplus] Oscillator part of BC-684 or BC-604 schematic?
WA5CAB at cs.com
WA5CAB at cs.com
Tue May 2 18:56:37 EDT 2006
Ian,
Except for the Power Amplifier (a 1624), all of the tubes are 1619's which
does have a directly heated 2.5 volt cathode/heater. If you can read the
numbers but are confused by the "M", remember that up until about the end of WW-II,
"M" = x1000. Postwar it became "K"=x1000. All of the resistors up to and
including the grid leak of the 1st RF Amplifier are 100,000 ohms except for R149,
between the oscillator grid and the crystal bank, 50 ohm, and R138, the
oscillator screen dropping resistor, 50,000 ohm.
Values taken from TM 11-600, May 14 1947, Figure 113 (showing MWO changes).
In early production, R118, the plate dropping resistor, was a single 30,000
2watt. This became three 100,000 2watt in parallel.
In a message dated 5/2/2006 5:17:17 PM Central Daylight Time,
ianmwilson at earthlink.net writes:
> Would be grateful if someone has a legible copy of one of these schematics
> and could tell me the component values around the oscillator (top left).
> Also would like to know the tube type - looks like 1619 but the tubes are
> all drawn as if directly heated.
Robert Downs - Houston
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