Wednesday, October 19, 2016

external l.o. 1150MHz connected to DB6NT

The original 96MHz  x12  chain  was at 1150.010   10kHz high  could not correct it 
Also showing the usual temperature drift as most  x-tal 's have and  a bit too high in frequency
I cut the 8V supply of the internal  X-tal 96MHz  x 12 3 stage part
and fitted an SMA for the external l.o. the 1150 is injected trough the 1152 helical filter using a 4.7 pF coupling C  . The 10 OHm chip to the disabled tripler transistor was removed. 
The signal level at the mixer is enough also with this 10 OHm left in.


My effort to replace the internal l.o. 1152MHz  using ADF4351A PLL 35 - 4000MHz demo board 
or the GPS locked Progrock oscillator output did not result in a good quality signal.
I decided to buy a DF9NP ready build PLL for 1150MHz switchable between 4 l.o. frequencies.      
Very quick build and delivered  by Dieter Leupold.  
Now with this external PLL the DB6NT  1.3GHz XVTR  is almost exact at at frequency.
This PLL standalone is producing a very stable and clean signal at 1150MHz .
using ADF4153 and TCXO  0.5ppm  -20 -- +70 C


The IC706 at 146MHz is now the weakest  part it needs a warm up time.
But the old IC706  was stable enough for 144MHz WSPR 
although it would be nice to have the internal l.o. stabilized same way. 

The ADF4351A test board is used as test signal generator  
1296.200  and the 10MHz overtone at 1300MHz is still a good strong reference signal
The ADF4351A signal is not as clean as the DF9NP PLL
Standalone with the onboard 10MHz xo reference it is to unstable to be used as local oscillator for 23cm   GPS locked  it is a very stable test signal.
  
Picture shows  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 
The  60m WSPR window fits to the older frequency allocation   
we are  not allowed to TX there


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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