Necessity The Mother Of Invention

So somewhere along the line, I broke one of the retention tabs in the charger base for the DMR radio. Got to thinking, i can buy a new one for $20 off ebay or I can Aussie it right up and just make it work. So with a bit of metal that came off the mower, 3 zip ties and a wedge of wood, I got the radio to sit in the right place to charge. HAHAHA


40m Vertical Tests

Antenna is a little bit long, but not much i can do to shorten it now, its a helically wound wire up a 10m pole. There are currently 3 radials under the antenna. 3 is obviously not enough, 8 would be minimum and 36 would be adequate, but after the following tests, I am pretty much settled now on building a 40m vertical out of aluminium tube and putting down 36 plus radials.

+7 in the Canary Islands, I doubt i have ever been that strong before and I know that the spots from the USA are all higher than I would typically expect with my low power operation.

The real clincher was the RBN spots. I have never had so many spots from a couple of calls.



Needed an antenna back up for 40m since i broke the portable dipole and cannot find the parts in my moving boxes to fix it. 40m vertical it is then, 3 radials for sub par performance and a can do attitude to make it happen. Ok, its windy, not just any old wind, its Ecca wind from the west so strong it would blow your panties off as you can see by the bend in the sotabeams mast looking more like a fishing pole with a 100kg tuna than a 40m vertical.

I was able to leave it up long enough to run some tests and see that it works, that the noise floor here is so low that a vertical is useable and that a 40m vertical made out of aluminium and a heap of radials might just be the answer to my antenna problems. More to come on that.


Starting To Feel Human Again

I should have actually posted this a week ago, but, have had the flu and pretty much have been in bed for a week. Just the flu mind you, not covid, but it really knocked the crap out of me, but thankfully I am slowly starting to feel human again and able to actually do something more than sleep and cough my guts out.

So i started to get the antenna situation here somewhat more permanent with the tribander now up in the air in its final location. I still have the radials to sort out and tune each band better, but initial thoughts is that the antenna hears better than where it was on the front deck.

But all things are not perfect, what I do have now is what i think is a ground loop. The noise that you see in the waterfall is actually noise from my PC.

The short video here shows the problem in detail. My gut feeling is that because the mast of the antenna is now grounded, rather than floating is that I have a ground loop happening. The entire garden frame is at ground potential, so i got a few ideas on how to solve the problem other than just turning off the computer. LOL

One thing for certain, i am getting a lot more spots on the RBN with the antenna in its current home. So onward and upwards. Now all i need to do is not feel like death and be able to get a 40m antenna back up since i broke my portable dipole and to maybe isolate the mast for the tri bander so its not all at ground potential and causing the loop noise i have.

But that is all for another day. For now, its back to bed and getting healthy again.


Tri Bander Back Up

A temporary mounting for now so i could prune the radials and get things working again.

SWR plot is ok on 20 and 10m and kind of MEH on 15m, but its always been kind of MEH on 15m. Actually if memory serves me correctly, this is the best plot I have ever achieved with this antenna LOL

These are just the numbers that go with the above plot. I can improve these numbers by adding in some more radials, 1 per band will work, 4 per band is reasonable. I think where I am going to mount the antenna, I should be good for 2 radials per band. At least for now I have all the bands I am interested in, 40, 20 and 15m.


Antennering It Up

There comes a time in every hams life when its time to erect that antenna. I am at that time where running out and switching links on the portable antenna is more or less a painful experience. So, its time to get the tri bander up and have 20, 15 and 10m on the one antenna.

Marking the hole for drilling.

Putting a round peg in a square hole and making sure it does not fall down.

Mounting the antenna to the pole. Still way more to go yet, but first is to find where the VNA is so that I can tune the radials to length before I mount it in its final position. Wont be to high in the air, but it will do the job.


Compare The Pair

Pretty much where we currently live is an RF canyon. The above 2 images are a comparison of where I am and where I am going. My RX has always been 3 or so S points down here compared to my TX. Simply because I have no view of the horizon. Essentially I am surrounded by obstructions, houses on 3 sides that are higher than my antenna, and only a few KM to the west are the great dividing range, mountains that are 500m higher than me.

The 2nd image is where I am going, where I have a rather uninterrupted view to the horizon. Not only will my noise floor be much lower, I will also be able to receive better because there is no real obstruction to attenuate the incoming signals. Beggers cannot be choosers most of the time but after 10 years in a sub optimum environment for RF, I am looking forward to going somewhere that is going to be much better. But hey, I worked 2 DXCC’s from this crap location. Not bad all things considered.


Crystal Filter Perfection

Sometimes, just sometimes, all your ducks align in a row and you build something that is dead set on the money. I think today I have done just that with this crystal filter.

Firstly I have redesigned the PCB board and test jig setup I am using, making construction just a little bit easier and allows me to easily use the slightly larger binocular core.

But secondly, I think i hit the nail squarely on the head, with this filter. I mean its almost perfect. 5dB loss, great, good shape factor, great, -55db stop band, great, exactly 2200Hz passband PRICELESS. I honestly could not have done better even if I tried. Now to build the receiver board and pray to Jebus that it works as good as this filter looks.

As a bonus, here is his friend the CW filter, 600Hz wide. A little more lossy but still good stop band and shape. I was shooting for 500Hz, bit I need maybe another 15pF per node. Good enough for me though, that is 2 filters for a receiver, 2 filters that should perform reasonably well.

Final EDIT:

So I was going to upload the gerbers and create a great big post about how to use them. But, i went looking for the files and it looks like I have deleted them by mistake when cleaning up my project files. I got no idea how I did that, but they are gone and its a lot of work to recreate them, so there will be no release of these PCB files. Lucky for me I can reorder them easily and I also have enough board here to make 20 filters, that should be a life times supply for me. Rather sad really, because they work so well.