ICOm sent me the following project to make ICOM rigs operate at QRP
levels. I would appreciate it if someone would tell me how to do an
earth ground with the battery, R2 and the cable (my shack is on the
second floor). I have tried to find the answer in books from the
library but can find no discussion. One reference seemed to suggest
that they should just be taped so there will not be a short and
forgotten.
*********
QRP MOD FOR ICOM HF TRANSCEIVERS
(from ICOM, dated 6/1/94)
/
|-------------/ *----/\/\/\/\----|
(-) | S1 R1 | to
*-----| | ALC
< jack
9 volt alkaline battery R2 > <--O ---------O----->
< | shielded |
*-----| > | cable |
| < | |
| | | |
| *----| |
| | |
----|---- ----|---- ----|----
----- ----- -----
--- --- ---
With this circuit connected to the radio, the power output is
adjustable between 0 to 100 watts. For best results, leave the RF
power at maximum and adjust for desired power using R2.
S1 is used to turn off circuit when radio is not in use or QRP
operation is not desired.
Radio Model: R1 Value R2 Value
IC-761, 765 47K Ohms 20K Ohms
IC-720(A), 735, 740, 2M Ohms 1M Ohms
745, 751(A), 275A/H
IC-725, 726, 728, 729, 220K Ohms 100K Ohms
736, 737(A)
*********
Thanks,
Jeff Hahn, KR4YS
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