To: softrock40@yahoogroups.com
From: "kb9yig"
Subject: [softrock40] 40m/30m RXTXv6.1 operation

Good Evening All,

This afternoon I finished the build of a 40m/30m RXTXv6.1 that I
started yesterday. Total build time was about seven hours.

The 40m RX function was working properly on first application of
power with a center frequency of 7.055 MHz. However, the 30m RX
function was not working properly which was traced to low amplitude
40.5 MHz clock output from Q11, the oscillator buffer stage. Output
from Q11 became solid for clocking the FFs after the value of R56 was
lowered from 22.1k to 15k.

I have seen this problem before with 30m SoftRock receivers where a
combination of 40.5 MHz crystal activity and transistor gain result
in a too low amplitude clock signal to the FFs. This will be
something to watch for in the 30m/40m kit.

After getting the 30m RX function working properly a test was made of
TX output to a 50 ohm load by using a quadrature audio line-out
signal to the board. On both 30m and 40m about 1.2V p-p quadrature
audio input produced one watt output where R3=R9=4.99k on the circuit
board. Max power output was greater than 1.3 watts on both bands when
the audio input was increased to around 2V p-p. The output sine wave
looked clean with the carrier suppression greater than 50 dB on both
bands. Others who have a spectrum analyzer will need to confirm that
spurious emissions are below the -43 dB FCC requirement.

Quite a few of the 40m/30m kits have been shipped in recent weeks and
I wonder if other examples of this kit have been built and tested.
Please post your experience with RXTXv6.1 30m operation or problems.

Thanks and 73,
Tony KB9YIG