Very interesting Maynard. I am not sure I am seeing this straight
but it appears that there is an RC load on the RF tube coupled via the
2.2 uF cap to the tuned circuit of the mixer grid. Should result in a
fairly low gain and fairly broad tuning. That might be desirable for the
broadcast band I am still not sure how the antenna coupling works for a
balanced input.
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On 2/14/2025 6:45 PM, Maynard Wright via groups.io wrote:
Hi, Richard,
You are right about the two small caps. But trace carefully what S1B
(front) is doing when set to Band 1. The RF signal is passed from the
plate of V1 through R4 and down to R26/C29. It cannot appear below that
RC combination because the B+ line should be at ground for RF. So
without C62, there is no path for RF forward from V1, at least in the
schematic.
So I wonder whether Emanuele might achieve good results across the full
ranges of Bands 1 and 2 by adjusting the amount of capacitance his
gimmick provides or by using a 2.2 pF cap as in the S-40B.
73,
Maynard
W6PAP
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
