LZ1AQ Active Amp and a "Fat" Lazy loop - Dual Opposing Loops.
Hi All,
Ive just finished installing my LZ1AQ using what used to be the copper loop I used on my MLA30+
I "Think" I have it configured OK, however I have a couple of things I am unsure of (the instructions are a bit of a challenge at times, as I think they are translated from German to English.)
- The connector on the control board for the switches. I currently only have one antenna configuration and no switches. Looking at the schematic for it, I should be able to short pins 3 and 6 to get the desired effect of a Single Loop antenna on A.
- Figure 2.4 in the manual here
- The next thing is the V1, Ground, V2 connectors on the amplifier board. I assume I dont need to use this for a single loop?
Apart from that, I think it's working OK!
Comments
Hi,
Yes, for a single loop connected as "A" connect pins 3 & 6 together.
You don't need to use V1, V2 & Ground for a loop, those are only required if you wish to use a separate pair of dipole elements.
BTW The thing that catches many people out, is mentioned in the two notes highlighted at the beginning of the instructions.
IMPORTANT !
The Control board must be with removed jumpers J5, J6. Connect to J2 the mode control switches. Connect the PS output to J7. Be sure that the green LED is ON. That means that the polarity connection is right.
The Amplifier board should be with removed jumper J6. Connect the two boards with FTP cable crimped by the user. Be sure that the green LED on the amplifier board is ON. That means that the PS connection is right.
It is a very versatile amplifier with lots of options you can try, but as you have discovered, it can sometimes be tricky to ensure that you have selected the correct jumper configurations.
Good luck,
Martin
Yeah then the next line says:
"Connect J6 on amp. board. Insert jumpers J5 and J6 on the control board. Measure the DC voltage between CP8 and CP11 and make sure it is between 11.8 – 15.7 V. Toggle the switches. Slight clicks from the relays should be heard. That is all."
Which is what I then did.
Ok, I have all the jumpers set correctly.
I'm not overly happy with the loop. I think I might make a bigger one!
On the plus side, the noise floor is much lower than my Apex Radio.
Once I get the antenna switch installed, I can do a side by side comparison, and get some more antennas.
What have I become! :-D
I have also managed to get rid of a lot of the noise spurs too with that being most of the signals around 22mtrs and above.
Don't confuse lower levels with lower SNR, which can sometimes happen. A properly operating loop should have ultimate performance very similar to a similar sized dipole probe, at least up through mid HF, modulo antenna pattern in az&el which can favor one or the other depending upon what you consider 'better'.
As LZ1AQ has written, making a small lowZ system reach propagated noise limits in the quietest locations may be impossible at the high end using components known-to-mankind as it is for small dipoles. But in general if/when all the other system noise ingress, noise floor, and IMD are pushed below the propagated noise produced within either antenna's radiation resistance the limits are very similar.
So I made this today.
Some PVC for the main body, and 16mm copper, used in HVAC, so it's quite soft. I've made it as round and as level as I could.
I'm using shielded outdoor Cat6 but it's a real PITA, so I will swap it out for shielded cat5e
Yes, that's an umbrella stand! :-)
Well had everything running nicely, and then this evening this mess appeared. Switched back to my Apex Radio Antenna, and its the same result - sigh.
Ah - I realise what that noise is - florescent lights in my garage! Man they are noisy - I haven't seen it like that before though.
Are there public kiwisdrs with LZ1AQ amp loops? I would be interested on looking at their performance.
Not to sure
you are welcome to look at mine.
You might find asking in the Loop Antennas group over at https://groups.io/g/loopantennas
Found one in the public Kiwi list here
Not sure how popular I have made myself.
I might shorten the pole as its in two sections. we will see...........
It actually doesnt seem to perform very well up there. It actually worked better sitting just above the fence line. Hmmmm
Well, this works better. I suspect the roof had a part to play in the loss of a lot of signal?
Broadband loops don't have to be mounted that high above the ground. 2m is about the optimum, and my loops are actually ground mounted in among some bushes.
The key thing is to get them as far away as possible from potential noise sources. They don't significantly interact with nearby objects, which means that you can often locate them in spots that would not be suitable for other types of antenna.
In addition, you can rotate them so that local noise sources are nulled out, and moving them slightly can help ensure that the null does not fall in a desired direction.
Keep experimenting until you can't easily obtain further improvements.
Regards,
Martin
Well, its quite interesting that just moving the antenna a few feet, seems to increase the SNR by several dB.
I really only put it on the garage roof to get it out of the way - however, I was quite disappointed with how it performed.
I'm thinking I will add a second loop like this:
You can get soft (annealed) 15mm copper pipe used in HVAC which gives it great stability yet easily worked into a fairly decent circle.
Well I don’t live far from our local industrial area and there are plenty of hvac companies there. Ask and thou shall receive
BEHOLD!
"Well, its quite interesting that just moving the antenna a few feet, seems to increase the SNR by several dB."
This is characteristic of near-field QRN/QRM. Field strength from nearby coupling can drop at fourth, sixth or even higher powers of distance. Once common-mode ingress has been controlled at least at longer wavelengths these are the coupling mechanisms that remain.
This is actually a saving grace for amateur radio. If QRN was all inverse-square, far-field radiation, all hams in a large geographical region would be similarly limited, there would be no 'locals' who receive well. Fortunately for the hobby this is not the physics.
@G8JNJ - Martin could you review this switch config for the pins 1->6 on the connector?
I "think" have it right. I've been staring at it for a while now, and brain fog has set in. I'm finally getting round to building the switch box for the controller.
Much appreciated!
Also looking at that, A+B Loop would be pins 1,2,3,4 and 6 tied together - although just 1 and 6 should do the same?
Yes, I think 1 & 6 connected alone, should be loops A & B
I believe you have 4 & 6 transposed on S1 in your switch diagram
Regards,
Martin
Many thanks for that. :-)