Wednesday, October 19, 2016

external l.o. 1150MHz connected to DB6NT

Improved the DB6NT  1.3GHz XVTR  to be almost exact at at frequency.
 with external PLL at 1150.00000 MHz 
The original 96MHz  was 10kHz high  could not be tuned lower 
Had the usual temperature drift like most  x-tal 's  a bit too high in frequency
Received   this nice PLL  unit from  DF9NP   1150/1152 MHz local oscillator
It is the box left very quick build and delivered  
Very stable and clean signal  from this unit.
using ADF4153 and TCXO  0.5ppm  -20 -- +70 C

standalone already  very stable 
The weakest part is now the IC706 that needs a warmup time to become stable
But this IC706 is stable enough for 144MHz WSPR so it is not that bad
My ADF4351A test board is used as test signal generator
1296.200  and the 10MHz overtone at 1300MHz is still a good strong reference signal
I switched off the internal  X-tal 96MHz  x 12 3 stage part and fitted an other SMA for the external l.o.
The ADF4351A signal is not as clean as the DF9NP PLL
And standalone with the onboard 10MHz xo it is to unstable to be used as local oscillator for 23cm
but GPS locked  it is a very stable test signal.
  
 XVTR  with Antenna relay and external 1150MHz l.o.
146  - 148 MHz  #  1296 1298MHz
The l.o. is switchable  to 1152

and can shift - 28 or + 28 MHz for repeater use.
however the DB6NT design is small band using helical bandfilters
i could not get 2W on all shifts
it should be possible to tune the 28 down 1122Mhz  and 1150 to have full output.



No comments:

Translate