IARU 50MHz 17 18 June




Saturday morning new constructed 7ele 9m3 boom V-dipole radiator was placed in the mast at 22m a.g.   Replacing the HF + 5e combi

After frustrating experience with JT5DX
14 June 16UTC CW 519 1 hour copied cqcqcq
called 100+ times no response
Time for another attempt to improve the 6m set-up


Band was closed Saturday morning  even quiet at the JT65 276 !
It looked like it's gone be a contest type propagation weekend but....
In afternoon right from start huge activity strong ES signals  all Saturday.
Mostly EU  but also  PJ4NX  and PJ7/W9DR


Saturday even small pile ups   SP OK UA I S5 9A
very short skips  IO80  600km   EI SP OK
We where again in the middle of the reflection cloud
203 QSO first day   added only 70 on Sunday
Sonday Es signals still strong but hard to find new ones.
We just do not have a lot of customers at ES distance from  our QTH
East EU could tank G's and DL
The E skip from G land lands in more ham / contest populated area's it seems
Relative high QSO number exchange  from G and  UR   mostly Ukraine area.
 Not only most QSO points are going over our head but also DX is does not land often here.
As if a magnet is pulling DX to the south..  in fact it is the earth as a big magnet ..

no complains with 284 as QSO number more QSO then expected.

Could not find simple  IARU rules for this contest.
On the IARU site this contest does not exists at all!
The IARU VHF managers handbook 144 pages! that scared me off.
Could not find a brief contest description like at the PG7V HF contest calendar.
This IARU 6m contest is not supported by real time contest reporter.
It is a very strange contest every June:
1. What is the name of this contest?
2. What is the N1MM contest type to open.
     I used VHF serial that type fits best.
    In N1MM, moving  data afterwards between different contests types is  almost impossible
    Certainly a job not advised to do during the contest.



My home made 50MHz  7 ele Unda / Yagi
Is a 7 ele 28 Ohm  9m30 boom  design   DK7ZB  but with a V dipole to match 28 to 50 OHms

The boom is 2 sections 6m 45x42 plus  3.5m 40x 36mm ( better is 1.5mm ST50 type Alu)
It is  relative light   lighter then the 5e + HF combination

In my opinion the best way for maximum stiffness ,for a boom naturally, is to use a relative thick diameter middle section
I have an old Fritzel FB33 5m boom  50x47 this is hi quality tough ST50? Alu
and extend this with 2x 40x47mm  both sides
Not  thicker then 1.5 rather use the right alloy Aluminium.
Another mistake is using  car Muffler clamps and tightening them as used with steel pipes as some hams do. The smooth braces do not have grip rather bend M6 wire thread
ant make aluminium saddles of U profile Alu.
The boom  was used with a previous very heavy 7 el 16mm elements yagi
And was constricted at the clamps positions.
It was attempted to strengthen the boom sliding in  a 3m piece 40mm tube
That made it even  heavier and not easy to remove this tube due to the constrictions.

The radiator dipole 12mm had to be cut to  2 x 140cm for 50.0 50.8Mhz segment  original given 143cm was too low in frequency.
When i looked back to my 9 ele 9m50 boom 30 years ago i saw its director was  280cm
 This Yagi described in the 1960 fb VHF handbook was a pre computer design
nothing wrong with that..
https://archive.org/details/VhfHandbook  W6SAI W6QKI

I could test it on a small 4m mast and found that the matching SWR did not really change a lot by the V angle  i fixed it at 30dgs bending backwards.
Sliding the coax dipole connection point  upwards from the end tip did not change minimum  resonance / SWR point  either. That makes sense now i could  see that myself.
The resonance is determined by the length and diameter of the dipole sections
   plus stray capacity,  the air gap in the middle does not effect the resonance point.

A good high antenna is important but  i have no illusion that it will make up the difference in DX compared with South EU    only some dB more signal i hope.
Deja vue 20 years ago i wondered how can SP DL OK HA UA work deep into USA over our heads and we don't hear a whisper. The radio path must be over south it is not  as nicely projected over the shortest  great circle distance.

We hear al EA I  9A S5 HA UA CT loud and the TV band 1 if still exists loud too
But we can't hear the real DX worked by those HAMS
with some exceptions of course.





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