Donald Ray West <[EMAIL PROTECTED]> made an utterence to the qrplist gang
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I've got this old Hawk rf amp that uses two 6GK6s in parallel
grounded-grid, with a 6AQ5 cor. The pi tank coil is mounted
practically on top of the two 6GK6s, where coil heating is
absolutely going to happen, and the pi tank caps are actually
screwdriver-adjust trimmers. But, it's a nifty little metal box
with a power supply, three mini tube sockets (2 9-pin, 1 7-pin),
a 4-position band switch and a relay already mounted, and should
make a great QRP TX platform.
I'd like to stick a triode/pentode combo tube in one of the 9-
pin sockets, such as a 6AW8. Being greedy, I'd like to have a
VFO circuit.
The VFO circuit below was borrowed from the "Vackar VFO", which
used a 12AT7 dual triode as vfo and amp. The RF amp was borrowed
from a 6GV8 design, via ARRL Handbook (1973) and (I think) Peter
Parker. VFO values are for 80m, and Z1 is a typical parasitic
suppressor.
Might this work with a 6AW8? VFO values are for 80m.
Gnd--.01---+--B+=255VDC--------
| |
RFC RFC
| |
---------+-----------+--100pF------- +--.005-->To Pi Tank
| | | | |
25 .001 | | Z1 B+
uH | | | | |
| Gnd | | | 22K
+------ | | Plate |
| | | | Screen---+
Tune 50pF | +---Grid |
50pF | Plate | Cath .01
| +--100pF-+----Grid 27K | |
Gnd | | Cath | Gnd Gnd
.001 100K | Gnd
| | +--.001--Gnd
Gnd Gnd |
RFC
|
+--.001--Gnd
|
Key
|
Gnd
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