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I didn't touch R65. Changing its value changes the DC operating
point at the collector of Q6. R63 has almost no effect on that,
since the current is set mostly by R64 which is bypassed for
Looking closer at the circuit, it is Ok to change R65 to 2K and
get the same result since the DC operating point will move down
from about 10V to 8V. It is easier thought to do the rework by
tacking a resistor across R63 rather then removing and replacing
R65. Either way works.
On 4/27/2018 10:03 AM, Skip Davis via Groups.Io wrote:
Howard did you also change out R65 that was posted here too.
By the way the parts showed up here yesterday, thanks a lot.
Now to find time to install them.
Skip Davis, NC9O
On Apr 27, 2018, at 09:57, Howard Fidel <sonic1@...
Yes. Change R63 to 24 ohms. The
earlier rev boards had 100 ohms there, and V3 has 47. I
put another 47 ohm resistor in parallel with the one on
the board. Now I don't need to yell into the mic.
On 4/27/2018 3:22 AM, iz oos wrote:
I have checked SSB output for the Ubitx using a
Softrock sdr receiver. The carrier is well aligned and
the filter gives a very good shape. Whistling is gives
full output with the stock mic element. The output seems
clean but the average power during normal speech seems
to me a bit low. Is there an easy way to increase it?