Stacked Pair of M² 6M7JHV's for Six Metres
This is a Polar plot of my pair of 6m7jhv's which are stacked 5/8 λ apart.
I Adjusted the Jhv's
for the lowest S.W.R.
on 50.110Mhz
Lehoto Caption
Crane Photo Caption
Picture of my 6M7JHV's.
The Stub mast is a 20 foot aluminium scaffold pole with a 12 foot by 1-9/16 “ thick walled aluminium tube fitted inside the base of main pole To give extra strength in high winds. Also there is a 5 foot pole at the top to support the guy rope.
M² 6M7JHV
SPECIFICATIONS
|
Model |
6M7JHV |
|
Frequency |
50.0-50.4 Mhz |
|
Gain |
10.9 dBd |
|
Front to back |
25 dB |
|
Beamwidth E - Plane |
E=40° / H=42° |
|
Stacking Distance, Max |
27' Wide, 25' High |
|
VSWR |
1.2:1 |
|
Power Handling |
1.5 KW |
|
Match Type |
" T" Match |
|
Balun |
4:1 Coaxial |
|
Lightening Protection |
All Elements Grounded |
|
Feed Impedance / Conn |
50 Ohms / "N" fem. |
|
Boom Length / Dia |
30' 8" / 1-1/2" O.D |
|
Element Type |
3/8" tube |
|
Mast Size |
2" others optional |
|
Wind Area / Survival |
2.5 sq ft / 85 MPH |
|
Weight / ShipWt. |
17 Lb / 20 Lb |
Cellflex properties
Phasing harness consists of ¾ λ (lambda) Tee connector & 1 ¾.λ Of 75 ohm Cellflex. (Type of Heliax) other coaxial can be used just change the velocity factor
1/4λ @ 50.1Mhz 300 / 50.1 / 4 = 1.497mtrs x 0.88 = 1.317 x 3 for 3/4λ = 3, 952 Mtrs
1 3/4 λ = 1.317 x 7 = 9.219Mtrs
As 3/4 λ @ 50.1 MHz = 1/4λ @ 16.7 MHz. Cut small pieces off And test with antenna analyzer at 16.7Mhz.
Make sure you short the far end each time you cut a piece off, and check resonant frequency
What you are actually making is a ¼ λ stub
The 1 3/4λ length can be cut by setting analyzer or dip meter to 7.157MHz
 |