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.




60m WSPR last night  after "repair" high SWR 


TimestampCallMHzSNRDriftGridPwrReporterRGridkmaz
 2016-10-19 01:32  ZS1OA  5.288692  -23  0  JF95fx  5  PA0O  JO33hg  9774  353 
 2016-10-19 03:26  ZS6KTS  5.288656  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 02:58  ZS6KTS  5.288656  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 03:06  ZS6KTS  5.288655  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 02:06  ZS6KTS  5.288656  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 01:48  ZS6KTS  5.288656  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 01:32  ZS6KTS  5.288656  -24  -1  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 01:12  ZS6KTS  5.288655  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-19 03:38  ZS6KTS  5.288656  -25  0  KG43cw  5  PA0O  JO33hg  9065  347 
 2016-10-18 23:26  ZS6SRL  5.288742  -22  0  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-18 22:58  ZS6SRL  5.288742  -24  0  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 02:52  ZS6SRL  5.288742  -20  0  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 02:44  ZS6SRL  5.288741  -20  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 02:32  ZS6SRL  5.288741  -17  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 03:12  ZS6SRL  5.288741  -17  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 03:24  ZS6SRL  5.288741  -16  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 01:48  ZS6SRL  5.288742  -18  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-18 23:38  ZS6SRL  5.288742  -21  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 01:24  ZS6SRL  5.288742  -16  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 00:12  ZS6SRL  5.288742  -21  0  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 03:44  ZS6SRL  5.288742  -21  1  KG33wv  10  PA0O  JO33hg  9062  347 
 2016-10-19 02:38  GM8DOR  5.288699  0  0  IO86ho  2  PA0O  JO33hg  738  116 
 2016-10-19 03:24  G4ZFQ  5.288663  -23  0  IO90ir  1  PA0O  JO33hg  611  59 

after the long expected rain yesterday the SWR went high on my 30/60/80 triband sloping dipole
 i use 25m   of H155 50Z 5.2 mm cable 
H155   -3dB  100m 10MHz    5kg 100m  low weight easy to  hoist 20m up together with the 3 dipoles the  total weight is reasonable low.  AT the cost of some dB  loss 
And  with 5.2mm it can pass trough the choke  Ferrite rings used as bal-un 

But it's PVC protection outer layer is very thin and after some years it will water in

That happened here  the shielding bread and  foil is complete oxidated
the core PE foam isolation  and center lead  look still okay  but the PL259 type connectors have to be taped in very well to be water resistant
This cable is the best for its outside dimension to get but it's indoor use.
The PVC outer shield will let in moist at long term.
 Still is  working well  why would oxidation of the outer shield give more attenuation?
As long as the dielectric intern is not damaged the cable should still perform well 
Only the skin effect could result in more cable loss.

after i cut off some parts and  soldered a new PL259  the cable was okay
But i have to be replaced  soon.
Possible with Highflexx 7    -1.9dB 100m 10MHz   o.d. 7.3 mm.
Will not pass trough the Ferrite core
 7kg/100m   40% heavier
This types are the lowest loss available today at 5.3  / 7.3 mm outside diameter

                                                             H155 white corroded bread and foil




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