Did you order the receive crystal for high side injection? A radio starting in
the range you have usually will tune right up with no oscillation problems if
the crystal is on the high side of the receive frequency. No mods are usually
required at all for moving a radio into the ham band if high side injection is
used. I have seen sensitivity of . 7 to 2 uV show up with a low side crystal
(with no mods) and have seen the sensitivity come to the .35 uV range by
shifting to a high side crystal.
The high side injection keeps the oscilator/multiplier chain in the normal
range for the radio and keeps things tuning to actual resonance and not just
close to resonance.
73 - Jim W5ZIT
Doug <[EMAIL PROTECTED]> wrote:
Is it normal to see some instability while tuning the rf and osc/mult
section of the Mastr II? The unit is similar to the front end of the Exec II
and I have tuned lots of those with no sign of instability but my
first Mastr II
does. The tuning of C305 seems to really set it off. The unit is 150.8-174mhz
package. On first try I could not get a signal through it. I changed
the G8 pre selector
with a G7 from a exec II and still no joy. I then modified the
osc/mult section
according to the article in the Repeater Builder files and it came to
life. But,
at time Q402 in the osc/mult cct gets very hot. and there is some instability.
The Osc/Mult seems to tune the way it should, and so does the first
two helical.
The unit was originally tuned to a MTS channel in the 150 mhz range
and checked
out fine before putting the new xtals in...
Does anyone have any comments about this ??
Thanks
Doug
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