EME - Is it raining? Antenna Time!

The one thing that I've been dreading is figuring out what to do for an antenna. I had a good time playing around with building my own 1.2 GHz Yagi antenna. But the reality is, if it's less than 40 elements, I don't think it's going to do much in terms of getting any signal to the Moon, or even receiving for that matter.

Here are a couple of pictures of what I was doing, and frankly I really wanted to put this together so I could do some testing at a smaller scale without the antenna that I'm eventually going to be using. 

I tried a couple of different matches, and had the most trouble with the gamma match - I think the beta match was the best for what ever reason.  The elements were purchased as 3ft rod from home depot and sawed down to size with a band saw.  Fun project, but it was extremely short lived... because I needed a REAL antenna.

So what is that antenna? Well, let's just say that it's the most expensive umbrella I've ever purchased... in orders of magnitude. 

I ordered two of these umbrellas from Paul from sub lunar https://sub-lunar.com/  He was able to get them out to me rather quickly, and they were packed extremely well. 

Super excited to open it up, I had a dilemma because I had difficulty determining how and where I was going to do this without damaging anything. 

So what's one to do? Put it on your hitch Mount of your truck of course!

Paul recommends Scotchgard on to protect the fabric, so I took the opportunity before I got too deep into this project to order some and get the antenna sprayed down. I used one can, but realistically probably should have used a second canned because I think my spray pattern was a little light. 

The other challenge was, how am I going to rotate this thing. Yes, we need to rotate it left and right on the azimuth plane as well as elevation. The Yaesu 5500 was my first choice, but when Eric saw what Paul had in his arsenal of possibilities, Eric and myself both ordered one for each of us.

The more adventurous one, Eric ended up replacing the motors and the encoders. He's got quite a stout operation going. I'm going to continue with the ones that came with the antenna rotator for now, but may do some upgrading in the future.

Hey you might be asking, how in the world am I going to program this rotator to do what it needs to do. There certainly are a lot of electronics on this rotator, and Paul did a really great job with these circuit boards that show some LED indications on what the rotator element is doing. 

Fast forward, and we ended up ordering some Arduino boards and downloaded the k3ng rotator program.

Because we are a professional operation here, Eric wound up whipping up a daughter board to pop onto the Arduino mega. This allowed us to have quick disconnects for anything onto the rotator, and also gave us the ability to connect in a couple of other accessories like a GPS clock source. 

The rotator project is taken on a life of its own, and there will be a separate post for this because... You know... Modifications!

EME - Power, Power, and More Power

Gear acquisition mode continues...

As you can imagine, trying to get a signal to the Moon is going to take some power. I can't remember what the distance is, but it's so far, that your classic 10w 1.2 GHz transmitter is probably not going to make a mark. 

Additionally, as we start to try to listen for signals, the reflected signals coming back from the Moon are going to be rather weak, so... Again, probably going to need a amplifier for that. 

So here we are, trying to figure out how much power we need on the transmit side, and also looking at options for low noise amplifiers, or pre-amplifiers on the receive side. 

The fact that we have to have both of these in line with the transmit and receive is going to add some complication and require some switching, which I will talk about in a later post....  Particularly, if we have a low noise amplifier in line with the transmit sequence, And we don't switch it out of line, it will more than likely burn it out. 

So, where do we go for amplification at the 1.2 GHz range?  Seems like the no-brainer approach might be to get one of those really cool, well made, finally machined amplifiers (and Low noise amplifier for the receive) from Kuhne. 

One of the challenges was to determine how much power on the transmit side we would need. I think that was easily calculated by the amount of money that would need to be spent, and how complicated things may need to be with a power supply to support very high power output - so both Eric and myself went with the 250 w power amplifier - the MKU PA 23CM-250: https://shop.kuhne-electronic.com/kuhne/en/shop/power-amplifiers/MKU+PA+23CM250W+CU++Power+Amplifier/?card=971

This amplifier gave us what I think will give us enough power to reach the moon, and at least allow some of the big gun stations that are already doing Moon bounce a chance to catch our signal.  It was also considerably cheaper than the next step up which was 1.5 KW. (Although, as you can tell it really was pretty expensive)

On the receive side, we chose the MKU LNA 132-ah: https://shop.kuhne-electronic.com/kuhne/en/shop/MKU+LNA+132+AH+SMA++Low+Noise+Amplifier/?card=316

Looks like this is the super low noise pre-amplifier that will go near the antenna feed point.

Eric is going to explore a little bit about building his own amplifier at some point in time, but this gives us a quick method to entry into the EME space.

We do have 12 volt power supplies available, but with this power amplifier using LDMOS technology, it's going to require about 50 volts.  We were able to jump on amazon.com and find plenty of options (like Meanwell) that will give us 48 volts DC, which should be plenty - and if luck has it, there are probably some adjustments we can make to get that 48 volts closer to 50 if we want.

EME - The beginning of going broke

 I have always held an interest in continuing to explore the edges of ham radio, and what better Edge to explore is one of bouncing radio waves off of the moon!

I've always had an interest in this, but I know that in order to do something really effective with a Suburban lot, I really needed to get on 1.2 GHz. While there is certainly a lot of activity on 2 m, the real estate I probably would need for something like this with a multi-yagi array, would be somewhat prohibitive, especially from a spousal standpoint, so an idea of getting on 1.2 GHz with either a couple of yagi antennas, or even a dish made a lot of sense to me. But this whole idea had taken a backseat for quite a few years.

I can't remember who really started to kick off this whole journey, but my partner in crime, Eric, KC9QLO was definitely a trigger for me, and maybe I was a trigger for him, because before I knew it, we both bought Icom 905 radios, and started to build our own 1.2 GHz yagi antennas.

So here we are, in gear acquisition mode... At this point purchasing the Icom 905 to at least start with capabilities in the 1.2 GHz range. 

I will say, we do have aspirations of playing around with 10 GHz at some point in time, and maybe even some of the intermediate frequencies like 2.4 and 5 GHz.  Maybe those might be terrestrial explorations, we will eventually see.