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Showing posts from August, 2019

5/8 10m vertical and K3 with TR-2018 HD 144MHz

The impedance of a 5/8 wave vertical is given as (75 -425j) Ω
   needed is XL  +425j to balance out the capacitive -425
Rothammel  say  2.3uH for D/d=4000  the ratio of lenght and conductor diameter does have influence on the inductance the thinner the conductor the higher the inductance
The original coil in the base for 11m is  8 wdg 32mm = 2.8uH The CD 11m vertical matching uses a grounded coil with tap at 3 wdg to the center pin PL259.
This 0.64 wave has uses a series inductance to match not grounded
I could not find a match with a grounded tap that would protect against static discharges. 
The best matching found was a 3 wdg 50mm diameter coil of 2.5mm2
Way less then the calculated 2.3uH
according to this calculator only 0.3uH ...  more coil gave worse result....


interesting sources :…

Perseiden still a meteoroid shower?

Trying to find any sign of Perseid shower again this year
Until now 12 August just random reflections nothing above normal
1 or 2  DX reflections  / hour only

over the last days 
hrd R5WM KO72QI 1928km   few time's  1/2 QSO +17 / +17  but thunderstorm QRT
UR3EE KN88 2186km few times decoded
UA3AVY KO95  2100  1 CQ..
RX1AS  few times seen

few other with just 1 decode
over the night i left 144.360 monitoring almost no reflections seen

monitoring Graves 143.050  very few pings
sofar  no signs of Perseiden shower  just random reflections
high activity makes the illusion  like some shower is going on

maybe it has to come yet...

but only high power hams can make "QSO"  that take many endless repeating steps

most one time good strong reflection and then nothing heard i the next 30 minutes
no QSO complete here i was more listening and trying to get over 2000km
but did not succeed just too poor reflections here
 heard  2 long bursts over 7 seconds  of UR6EF and UT9UR