MDSR station gets new antenna - results of WSPR propagation test

Hi Everybody;

We have upgraded the antenna on the MDSR test station. The G5RV was retired and replaced with a "Double Bazooka" made out of RG-58. This antenna is a horizontal dipole, but uses coaxial cable instead of antenna wire. The advantage of coax, instead of regular antenna wire is the reduction of the wave propagation inside the coax. This velocity factor allows for shorter cable length - in case of RG-58 solid core insulation the velocity factor is 66% - which shortens the antenna significantly. The antenna was build to be resonant at 40m. Using a antenna meter to measure the antenna the resonance is actually just a bit below 7MHz. Interestingly enough the antenna is also resonant at 21MHz and at 54MHz. Unfortunately the antenna does not work well on 14MHz. The plan is to build another "Bazooka" specifically for 20m. The antenna is very effective and easy to build.
For more details check this link:
http://www.hamuniverse.com/n4jaantennabook.html
see chapter X section 5


The MDSR system allows the upgrade of a conventional radio into an IF SDR. By using your existing station and your computer this upgrade can be done very cost effective.
Please check the MDSR website:
http://users.skynet.be/myspace/mdsr

and sign up for updates on the MDSR project at this Yahoo user group:
https://groups.yahoo.com/neo/groups/mdsradio/info


In order to get an idea of how well this new coaxial antenna works we have set up the MDSR to work with WSPR at 40m (7.0386MHz). The test run at night (local time) after the 40m band opened. With only 20W of power The MDSR (FT-950) was able to connect with other stations as far away as Australia, Japan and Germany!

Please see the table below:
[TABLE]
<tbody>[TR]
[TD]Timestamp
[/TD]
[TD]Call
[/TD]
[TD]MHz
[/TD]
[TD]SNR
[/TD]
[TD]Drift
[/TD]
[TD]Grid
[/TD]
[TD]Pwr
[/TD]
[TD]Reporter
[/TD]
[TD]RGrid
[/TD]
[TD]km
[/TD]
[TD]az
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 10:18
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040112
[/TD]
[TD] -24
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK5ZRL
[/TD]
[TD] PF95gc
[/TD]
[TD] 13434
[/TD]
[TD] 251
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 13:36
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040130
[/TD]
[TD] -16
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK5EI
[/TD]
[TD] PF95gc
[/TD]
[TD] 13434
[/TD]
[TD] 251
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 10:36
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040121
[/TD]
[TD] -14
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK5AKK
[/TD]
[TD] PF94ix
[/TD]
[TD] 13432
[/TD]
[TD] 251
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 13:36
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040150
[/TD]
[TD] -2
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK7DIK
[/TD]
[TD] QE38cu
[/TD]
[TD] 13385
[/TD]
[TD] 241
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 13:26
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040134
[/TD]
[TD] -13
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK5MR
[/TD]
[TD] PF96lh
[/TD]
[TD] 13316
[/TD]
[TD] 252
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 10:18
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040111
[/TD]
[TD] -24
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK3DXE
[/TD]
[TD] QF21nv
[/TD]
[TD] 13231
[/TD]
[TD] 244
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 13:56
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040128
[/TD]
[TD] -9
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VK4SC
[/TD]
[TD] QG62og
[/TD]
[TD] 11884
[/TD]
[TD] 247
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 10:10
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040114
[/TD]
[TD] -23
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] DU1MGA
[/TD]
[TD] PK04
[/TD]
[TD] 10561
[/TD]
[TD] 299
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 10:18
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040110
[/TD]
[TD] -19
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] 7L4IOU
[/TD]
[TD] PM95wr
[/TD]
[TD] 7539
[/TD]
[TD] 300
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 09:50
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040144
[/TD]
[TD] -14
[/TD]
[TD] -2
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] WA4AMG
[/TD]
[TD] EL97uf
[/TD]
[TD] 4384
[/TD]
[TD] 108
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 09:50
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040119
[/TD]
[TD] -17
[/TD]
[TD] 0
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] K3ZV
[/TD]
[TD] FM29nt
[/TD]
[TD] 3888
[/TD]
[TD] 87
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 08:48
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040115
[/TD]
[TD] -11
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] N2BJW
[/TD]
[TD] FN34im
[/TD]
[TD] 3746
[/TD]
[TD] 79
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 11:48
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040085
[/TD]
[TD] -22
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] K4RCG
[/TD]
[TD] FM08xl
[/TD]
[TD] 3739
[/TD]
[TD] 92
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 11:02
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040152
[/TD]
[TD] -18
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VA3MW
[/TD]
[TD] FN03
[/TD]
[TD] 3386
[/TD]
[TD] 84
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 08:40
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040121
[/TD]
[TD] -13
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] KC9NBV
[/TD]
[TD] EM69oe
[/TD]
[TD] 3064
[/TD]
[TD] 98
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 12:46
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040133
[/TD]
[TD] -25
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VE3BDR
[/TD]
[TD] EN98il
[/TD]
[TD] 3013
[/TD]
[TD] 76
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 10:18
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040112
[/TD]
[TD] -10
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] KD6RF
[/TD]
[TD] EM22
[/TD]
[TD] 2980
[/TD]
[TD] 119
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 08:48
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040112
[/TD]
[TD] -16
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] K9AN
[/TD]
[TD] EN50wc
[/TD]
[TD] 2913
[/TD]
[TD] 97
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 06:42
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040131
[/TD]
[TD] +2
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] W5OXM
[/TD]
[TD] DM75
[/TD]
[TD] 2126
[/TD]
[TD] 130
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 12:46
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040141
[/TD]
[TD] -3
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] N6RY
[/TD]
[TD] DM13id
[/TD]
[TD] 1864
[/TD]
[TD] 163
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 08:48
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040112
[/TD]
[TD] -26
[/TD]
[TD] 0
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] AG6NS
[/TD]
[TD] CM97cf
[/TD]
[TD] 1352
[/TD]
[TD] 175
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 07:12
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040114
[/TD]
[TD] -22
[/TD]
[TD] 0
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] VE6OG
[/TD]
[TD] DO33fn
[/TD]
[TD] 807
[/TD]
[TD] 51
[/TD]
[/TR]
[TR]
[TD] 2014-09-05 06:52
[/TD]
[TD] VE7DXW
[/TD]
[TD] 7.040116
[/TD]
[TD] -15
[/TD]
[TD] -1
[/TD]
[TD] CN89li
[/TD]
[TD] 5
[/TD]
[TD] WK0I
[/TD]
[TD] DN17nq
[/TD]
[TD] 490
[/TD]
[TD] 110
[/TD]
[/TR]
</tbody>[/TABLE]

Thank you;
The MDSR Team

 

I have been using a homemade OCF dipole made from rg6 coax using only the braid for years. It is cut for 80m and I can tune from 80-6 with a tuner, I have fantastic reports with this type of antenna, and I find using this type of antenna it is very broad banded I can tune from one end of 20m to the other with minimal change in swr. I have ALSO made a 20 meter vertical using rg6 going up the center of a couple of lengths of PVC and again used the braid for the radiating element and some wire on the ground for radials.. Worked a lot of psk stations QRP 5-10 watts and had excellent reports as well.

 

These antennas sound very good. Please remember propagation plays A big part on who we reach around the world.
Just Sayin!

 

Love to see a picture of it and maybe some specs? 73'

 

Hi KC1MAC and everybody;

Here are the return loss measurements for both antennas.
Scan 20m antenna 2-54MHz
View attachment 198507

Scan 40m antenna 5-26MHz
View attachment 198506

Here is a layout drawing and the dimensions of the antenna;
View attachment 198519

Thanks to K4EFW for posting this.

Alex
VE7DZW

 

Congratulations on the upgrade, but I do have to ask; 20 watts using WSPR? You could just about work the world on a metal clothes hanger with WSPR at 20 watts. Would love to see some comparisons at 5w; the minimum for the 950 and still more than enough to be heard around the world.

73

Dave
K3DCW

 

Antenna Measurements and Design Drawing for "double Bazooka" Coaxial Antenna

Here are the jpgs again...

 

Hi Dave and everybody;

I agree 20W for WSPR is high, but it is still QRP and we are on 40m. It is the same power we are using with JT-65. It is easier to compare the results of the WSPR test with the JT-65 if the power levels are the same.

I have used the FT-817 with the MDSR software using 5W for JT-65 and WSPR using a vertical antenna in a portable setting and we were still covering extremely large distances. WSPR and JT-65 are well designed to penetrate noise.

73;

Alex
VE7DXW

 

Just incredible that a group dedicated to minimum power propagation studies would remove a G5RV dipole and install a Double Bazooka, and even consider trying to use it on multiple bands. *shakes head*

 

Hi KB4QAA;

We actually built two Double Bazzokas, one for 40m and the other for 20m. As our antenna measurement indicates the 40m Bazooka also can be used at 15m (3rd harmonic). There is also a drop at the 5th and 7th harmonic, which is at about 50MHz.
The 20m Double Bazooka is only useable for 14.000 - to 14.350MHz for TX operation with a SWR of 1.3 at the edges of the band.
There is also a benefit of a antenna with a smaller footprint which makes my neighbors happy....

Alex


The one for 40m

 

I agree. http://forums.qrz.com/showthread.php?164385-The-Double-Bazooka-Antenna

 

We actually built two Double Bazzokas, one for 40m and the other for 20m. As our antenna measurement indicates the 40m Bazooka also can be used at 15m (3rd harmonic). There is also a drop at the 5th and 7th harmonic, which is at about 50MHz.
The 20m Double Bazooka is only useable for 14.000 - to 14.350MHz for TX operation with a SWR of 1.3 at the edges of the band.
There is also a benefit of a antenna with a smaller footprint which makes my neighbors happy....

Alex

 

When did 20w become QRP? When did the band you are operating determine what the QRP power level is? QRP is generally recognized as 5w or less. QRPp is <1w. You're getting wide coverage with 20w? I would certainly hope so! Blasting out 20w is likely causing havoc with other users because WSPR is a weak signal mode.

Please reconsider your power levels.

 

Hi Michael and everybody;

I have checked the WSPR wesite for a maximum power level and there is none. As long as the power level is defined properly in the "Station Parameters". The output power level can be selected from a list and the maximum output power listed is +60dB, which is 1kW. Not that I would ever use 1kW for WSPR.
I have used my FT-817 with 1W with WSPR and the results are stunning. We used 20W because that what we used for JT-65. I should have taken into account the fact that the WSPR transmissions are much narrower in bandwidth then JT-65.

The general meaning of QRP is "Reduced or reduce Power". 20W is definitely reduced power.

All the best;

Alex
VE7DXW