DAC 144MHz

Very good tropo and great activity in analogue modes at good old 144MHz
The RSGB contest starting 1 hour later has very high participation.
in the end several contact numbers were over 200 like SK7MW
Took my old Braun SE400  back from the shelf.
It is sensitive low noise has just few internal generated birdies
No CAT connection in 1970  RF out is just below 10W.
So i had a handwritten log like in the 70'ties..
It can be modified  replacing the old hot TTL frequency counter unit box right (5V 2A...)
And install a PLL controller including CAT connection to connect it to N1MM logger. And WSJT-x








 On top new  5ele 4M - 7ele 2m duoband  Below  7 ele 6m yagi  home brew
Just in time this  4m / 2m duoband was ready in the mast that evening.
Based upon  DK7ZB 4m 5 ele and VHF 3 band  design.
 btw last weekend UKSMG contest Martin  IS0/DK7ZB  9++ signal...
I wanted to replace my 3 band mini beam with a bigger 2 band 4M 2M no 6M elements
Avoiding the risk to pick up too much RF from the 7ele 6m yagi below on the 2m set.

Added 7  144MHz  elements that fits on the existing boom.
The element sizes are based upon  DK7ZB  designs .
and the PA0MS legendary 2 beam  i have  broken one and missing 1 element
By adjusting the 2M element positions archived good match 1 : 1.5 for both 2 and 4m
Adding  2m elements will not affect the 4m tuning much
The 2m tuning impedance is  affected by the longer 4m elements.
The  Antenna is fed  50Z  without balun at the 4m dipole
Found the best matching with 2m parasitic radiator 3.5cm close to the 4m driven element that brought the SWR down to 1: 1.5
The empirical found positions of 2m elements differ quite much from the ZB 3band element spacing.
All elements are  10mm tube except the last 2M director an old Veron beam element i had left.
Elements are isolated from the boom using Stauf clamps 10mm for 4m
and some smaller 10mm element holders.
Fixed to the 20mm square boom 3m10  with 2 crossed Tyrap's (Tireps?)
Filed a 3mm deep 20mm wide slot in the Stauff clamps to keep them square to the boom.
With the advantage that they can be fixed without drilling and element spacing can be optimized.
Critical positions are the radiator and the first 2  directors.

With hand effect checking the SWR i saw that the 2m radiator rf was distributed symmetrical.
No no use for a bal-un but i kept the last part of coax free from the boom.
The first director is most sensitive it must be clear from other metal or even myself .
The SWR raised when approaching it.
I could not see any SWR change when touching the reflector.
Not even by touching it with an element rod.
2m reflector must have its function for F/B ratio
this has to be tested on a near field signal and then placing removing the reflector, would be interesting to see if the books are right.

Resume
The few year ago made DK7ZB  mini 3band  antenna performs good for it's small size 1m25.
It can easy stay in the mast and survive the winter season.
But the long 7 element 6m clearly picks up less noise from the neighbor Solar power installation.
On the DK7ZB mini beam the S-meter started to increase already halfway to the noise source
at  50m  probably radiated up from below.
The 7ele 9m yagi starts picking up noise first at about 10 dgs  from the noise source.
That brought down the 50MHz noise level a lot.
This Solor Edge PV SE8k converter was professional tested again by  A.T.
EMC department of  Telecom. And it failed the legal EMC norm.
So there is hope for a solution for the now over 2 year lasting RFI problem.

The fist tests with the 4/2 combi showed that it performs well
directivity is good  SWR is 1: 1.5
Compared to other nearby ham's it is doing well on 2 and 4m
but since Johan PF7M  is s.k. it is hard to know how good is good 

By coincidence the 144MHz montly DAC started just after the antenne was up.
And with exceptional propagation
f.i. G1YBB/P  IO82lb  booming S9  using 10W
Super tropo DX  the first test ! EI3KD in CW  1011km  my old Stiveco keyer was connected
and EI3KD came back right away woow that was al long time ago I heard / worked Ireland at 2m
This tropo condition was special  since the ducting did not stop at the coast as usual in summer evenings but it went deep over land.

OK1DOY 59 GI4SNA 59 GW8ASD/P GW4ZAR/P GD0AMD/P GM4AFF GM4BYF 59

I just made a super antenna ;-)
This morning  144402   OY6BEC IP62 heard S1 S2
A pleasure to listen with the Braun SE400 zapping the band..

  5 of 50 QSO are confirmed in LOTW  veryt few VHF hams use LOTW
 

DetailsPA0OEI3KD2018-06-05 19:33:392MCW144.19700IRELAND
DetailsPA0OG4KUX2018-06-05 19:27:192MSSB144.20000
DetailsPA0OGI4SNA2018-06-05 19:25:132MSSB144.22600NORTHERN IRELAND
DetailsPA0OG8KPD/P2018-06-05 19:22:372MSSB144.39500
DetailsPA0OG4TMI/P2018-06-05 19:19:472MSSB144.37100
DetailsPA0OGM4AFF2018-06-05 19:17:462MSSB144.34400
DetailsPA0OOK1DOY2018-06-05 18:56:032MSSB144.26400
DetailsPA0ODP9X2018-06-05 18:44:212MSSB144.21500
DetailsPA0OG1YBB/P2018-06-05 18:05:482MSSB144.26000
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