Saturday, October 19, 2019

10m&12m 19-Okt-2019

Started to monitor 10m with WSPR today, but it wasn't a success. No propagation? Well, I switched to FT8 and suddenly the spectrum was full of signals. ODX was V51MA Namibia today.


But wait, there is more....12m was buzzing as well. And strange thing, my CG3000 suddenly matched my vertical to a reasonable SWR.


ODX was FR5CB Reunion Isl.

Friday, October 18, 2019

4 element LFA versus HB9CV


Yes, here is the long awaited comparisation between the homemade HB9CV and the mighty 4 element LFA beam. Both on same height in the same tower, same coax, same test station with same antenna and same power levels. I tested with neighbourstation PA4O Peter who is living about 15km from my QTH.

We first tested with the HB9CV. I'm a HB9CV fan. I've made various HB9CVs in the past and they were always fine. Long time ago I had a 3 element conventional designed yagi and it was not half as good as the HB9CV. I made lots of DX contacts with the HB9CV and was even spotted in VK with 1W WSPR on longpath in 2015. That's why I'm always sceptic about theoretical numbers. Specialists will say that the HB9CV is of course not that good compared to a bigger LFA.

TX best signal was 6,5-7 at PA4O
RX best signal was 6 from PA4O









Last evening we tested with the LFA. Of course the LFA has 2 more elements and a closed loop as radiator. It is a incredible design and much better as conventional designs from last century. Of course this is not a fair comparisation but I wanted to be shure it the LFA is really that good. Not theoretically but under real conditions.

TX best signal at PA4O 8,5-9
RX best signal from PA4O 7,5-8

Theoretically because of the test results the LFA would be better as the HB9CV on this distance. I don't know what the actual specs are from the LFA. When I look around I see something like 14,2dBi. In dB that would be 14,2-2,15=12dB. The HB9CV would be doing something like 4dB but probabely on another angle. Difference between the antennas would be 8dB. In that case you would expect less as 2 s-unit difference. But of course a s-meter like we use in the IC-7300 and in Peter's case the IC-7410 is not that accurate and just a indication. The big difference actually is the front/side and front/back ratio. Wow, what a difference it is...

Yes.....I believe now, after this test, the LFA definitely is a better antenna. But what would happen if I extend the HB9CV with 2 directional elements?

Wednesday, October 16, 2019

QRPguys digital FSM continued

After waiting for a answer from QRPguys for over 2 weeks I noticed KY6R Rich wrote about a QRPguys "paraset" kit designed by Steve KD1JV. I thought Steve might be able to help me out with the modification on the digital voltmeter module. So I decided to send him a e-mail and within a few hours I had a helping answer. Actually basically it would be a trail and error try to modify the voltmeter, he explained how to measure from the yellow sense wire on which resistor to short out. He also told me instead of a 100V type I should take a 30V type without mod. But this solution would take weeks before I have a new module.



So I took another look at the diagram supplied with the kit. It shows a jumper from the yellow sense wire shorting out a resistor and a potmeter which are connected in series. Thinking that this is always the same whatever the lay out I started to measure several junction to find out were to solder the wire. The picture at the right shows the results. The conclusion is that when I solder a wire between point 3 and point 1 I short out the potmeter and the resistor below the potmeter which are obviously connected in series.

Not shure about everything but I decided to continue with the last part of the kit. Mounting the voltmeter and the sense potmeter on the printboard. Soon it was evident the bushings supplied could not fit, they are too wide (or the screws are too short ;-) ).  I decided filing them, but the material is very tuff. It took a electric powerfile to get anything off.



The result including the short out wire can be seen on the picture. Ready to assemble without any difficulties this time...



Below the finished project finally working:


Testing: I hoped for a more accurate FSM but so far it is just a indicator just like a analog FSM. The potmeter is not sensitive enough to set it to a accurate value. So, if you finally set it, for instance to 10 as a start value, next time you switch the meter on it is on 15. When you only touch the potmeter the value will change. I might look around for a 10 turn potmeter to increase the sensitivity in the future.

The push button, by the way, is a momentary on switch in parallel with the normal on switch. I had to read the manual several times before I discovered why it was there. Just for information ;-)