Ok, the MPAS 2.0 is a bit much to mount to thin sheetmetal, especially if there is any sort of wind.

She is alive!

Attached File


Attached File


Got a video I will edit and post to my ham youtube channel. So with 17dbm of drive or about 50 milliwatts of drive I am getting about 20 watts of output. That is at 51.4v on a current limited supply. At 61v getting 25 watts out. Pretty happy with that. Going to take my time to get this setup on the big supply. Have to decide based on the attenuator how I am going to do it. Needs more drive as the frequency goes up. Had to go to about 250 milliwatts to get the same power at 50mhz.

So far it is working well.

Last project for the weekend have a busy week this week. Got my $20 amazon QRP amp working last week. Made some power on the low bands. Playing with the bias and one of the “IRF-530” marked devices went into a dead short. Got the real ones from Digi key and put them in. Makes about 70-80w on 160m with 1.5w drive. Falls off quick as you move up the bands. Will be fun for a bench amp but will need a LPF because it is a nasty little critter. It was more for practice than anything.

Attached File


Harmonics on 80M
Attached File


There is a really cool 2”x2” amp that uses a single TO-220 device and makes a little over 100 watts. Think I will order the board kit and make that. They use a $20 buck converter on amazon for 12v to 48. Want a little amp for mobile use. Having a blast making these!

what is the name of what you bought?

The qrp amp?

Its one of the 70w kits you can buy on Amazon and ebay. I would recommend getting them off of ebay with the SMD part populated. Also the values of some of the resistors in the kit are not correct. I had to change some values. I had an issue with Bias and had to work through that. Got that fixed and the amp relay was not switching the RF channel. The board was not made correctly and did not have a ground for the field coil. Just made the solder bridge to the ground plane and it worked well.

100W Amp  Using MRF101A

Board Set $40

Indeed that is going to be my next Amp project with an Arduino controller.

@KB7DX been away from here for a bit to do other things. About to fire up the bench again and start building...lol
Update

I needed a loading coil for my 43' to cover a band my tuner can't do. The math says I need
9,593 uH.

It was a challenge to do by hand so I built a winding jig, and then spent the next four hours winding
the coil today. Finished it up, put it on the LCR meter and... 7,300 uH.

FML.

That's a 12" concrete tube as a form, with about 500 feet of 16 gauge magnet wire, about 220 turns.
Not sure why it's coming up so short on the inductance, but man did that let the air out of my tires,
not to mention kill my fingers.

You trying to work 160m on your 6m antenna?


Has to be 600m, 2200m low band stuff. Would like to know more of what you are building.

Close! Low band indeed.

1750M. It's an unlicensed band and after playing around with 80M for the 20-100 mile comms stuff and
getting working signals at milliwatt levels, I wanted to see if I could pull it off with an unlicensed frequency.

You're limited to 1W power input into the final amplifier (using the best current designs that results in about
700 mW out) and a 50' total antenna system length (transmitter terminal to end of antenna.) Thus you need
a loading coil like this. The crazy thing is this would be considered a pretty basic coil, there's stations using
refrigeration tubing or 3/8 thick litz wire for their coils, the typical ERP from the antenna systems is usually
microwatts and doing low-loss stuff like big conductors has a big payoff at such low power levels.

What got my attention is that the folks that do this (called "Lowfers") are super focused on DX, not local comms,
and several blogs casually mentioned copy at 100 miles using trivial antennas (like a standard 2M mag mount
with a preamp) like it was no big deal and happened all the time. One source suggested that antenna changes
needed to be monitored at a few tens of wavelengths away to know if they were effective. On 10M if you
monitored your antenna changes at a 1/4 mile, you'd be ~ 40 wavelengths away.

That same distance by wavelengths on 1750M is 40 miles and again copy here is apparently nothing
special. There's an old youtube videos of doing signal checks at 25 miles using a one foot loop antenna,
inside a car in an urban area, with easy copy.

Given weak signal modes like js8call/FT8 I pondered that it might be possible to make local 20-100 mile
digital communications work on this license-free band, so there's only one way to find out and that's get on the air,
hence the giant coil. I'm hoping to have the TX up and running in a few days, obviously I need to add more
turns to this coil to get where I need to be. Side benefit is most of the stuff can be easily adapted for 2200M if I'm so
inclined.

Got a bunch of parts in. Amp control board, RX/TX with Bias relay, RF delay relay, 50v to 12v step down regulator, attenuator PC boards, and the universal band decoder. I am going to be making my own Icom band decoder with another Arduino. I will install the universal band decoder but I want to make it so when the Icom is plugged in, it uses the Arduino. When the icom is not plugged in the Universal is working, and just needs a bit of RF with the amp in standby. If all else fails I will have an Analog band switch I can use. I also got a bunch of Molex connectors and some 50amp power poles. I need to get the chassis mount for 2 of the 50amp connectors. Going to run 2 of the smaller 50amp connector instead of a 120 or 175 amp.

Attached File


Control board uses a Nextion 7" display and an Arduino nano. Pretty clean overall but would like the ability to modify the code. I am going to place an order for some Custom PCBs that are open source and make some more amplifier control boards for some future amps and write my own code for it. I want to build a wattmeter/station monitor using a 7" nextion screen for a future project.
Attached File


Still need to get the High Voltage protection board, 2x dual directional couplers, and the Low Pass Filter kit. Once that is done I can begin to finalize how I am going to put this together and start getting the parts for the second pallet. Will need the spreader, board, device, and splitter/combiner network.

It is coming along but is going to take some time to make sure everything is right.

Mis spoke on the power output. It put out 1350 on 160m and right at 1k on 10m. Lowest band was 17m at about 950 and 15m was about 1200. This was a bit under 5w of drive. Measured around 600 out on 50mhz. Will take a bit more drive on 6m to get the power up. Looks like a 13db pad is going to be prefect for the single and dual pallet. Will limit the drive to around 7 watts. Even at 2.5w it was pushing 1K from a single pallet. So 5w into 2 pallets should push it well over legal limit and about 1200w on 6m with lots of head room. Very happy on how its working so far. Dummy load almost went into melt down and hardly any heat into the spreader and heat sink.

ETA: also got the base programming for an Icom band detector done using an Arduino. Think I will migrate this project to an ESP32 for a custom amp control board with some options I want to add to this amplifier. Using VScode to help with the progression and implementing it into Git Hub. Boards will be based on an open-source board system and probably make a daughter board for the add-on functions I want to do.

This took way more effort than I care to admit:

Attached File


Also thanks to whoever gave me a membership yesterday. I'm assuming it was someone
from this forum and not a fan of my shitposting in GD. It certainly makes sharing pics easier!

The actual antenna is even more narrowband than this, but when all was said and done and I
attached that honkin' big loading coil to the 43' and tuned it, it had an impedance of about 190 ohms,
so I had to build a matching transformer (which per above wasn't perfect and probably needs
some tweaks, since I'm at 71 ohms not 50.) The transformer dropped the direct fed SWR from about
6 to 1.57 but broadened out (e.g. lowered the Q) a little. Still super high Q relative to the typical
antenna which means it's at least a little efficient.

For comparison's sake, a 43' antenna on 1750 meters is 0.0075 wavelengths tall. The equivalent
sized antenna on 20M would be just under 6 inches high. Due to the rules it has to be base
loaded. As you might imagine such short antennas aren't terribly efficient.

Currently running a beacon transmitter and if my measurements are right, it's about 70% efficient
so 700mW-ish making it into the antenna. Typical efficiencies for antennas built way better than mine
are about 0.08 percent (so 0.0008 of input power, times 0.7 watts = 0.00056 watts, or 0.56 millwatts or
56,000 microwatts.) I'm sure my output is lower than this, but it's probably in the ballpark.

Anyway, I need to decide how much time to spend in beacon mode and go out an do some
reception tests but work is ramping up so it'll probably be a while. It's currently sending 5 WPM
CW and WSPR at 187.1 KHz (so 185.6 KHz USB for audio at 1500 Hz.)

Given the output and noise floor it's probably only detectable in the immediate area west of central AZ,
though it's not impossible a signal could make it into Phoenix and be heard at night.

What are you using for a TX?

A QRP Labs Ultimate3S beacon, set to the appropriate power level for 1750M part 15 TX limits, of course.
I have a few monoband versions of the QDX on their way and planned on one being for 1750M but I'm starting
to re-think that based on what I've seen so far.

I did manage to briefly do a mobile reception test this week and was very disappointed in the results,
which suggest I'm limited by ground conductivity here or need to try another antenna with a top hat
instead of the 43'. The signal was barely making a half mile (and that's using WSPR!)

If I have time after my work this quarter (so probably September) I'll try to do a wire top hat antenna but
I really think my mostly rock ground is the limiting factor here, the guys that really get out all seem to be
in areas with fairly favorable ground conductivity. My mountain QTH should be helping me much more
than it seems to be, so I'm guessing it's the rock.

I've submitted my station for 2200M and am in the waiting period, given how bad 1750M is looking so
far I think I can safely say it's not going to be a license-free option for any kind of useful local comms,
but I'll try a better antenna to confirm. After that it probably makes sense to try using higher powers on
2200M, and I'll probably set up the QDX for that instead.

Neat. Many years ago I was intrigued by 1750M and wanted play with it but never did. I think Palomar? made a TX for the band but not 100% certain. Somewhere I have/had the publication that was available at the time.

Almost all the tech stuff on the web for 1750M is from the 1980s, and I'd been intrigued by the band and my
recent pursuit of the 100 mile comms was motive to explore it. The LF/VLF stuff isn't easy to do
due to the lack of equipment and how hands-on it is to get an antenna working, you're not going to
pull it off without a lot of tuning and trial and error.

I don't know about transmitters but Palomar made a VLF upconverter that's well regarded from what I can see --
on that topic, my Icom 7300 is absolutely deaf on 1750M. I thought my beacon transmitter was broken,
but the sensitivity is just that bad, I didn't realize until I tried my 817 for a mobile receiver that the 7300
was so terrible. So there's probably still a place for a product like Palomar's. I've also discovered a lot of
radios don't even have general coverage down that low, the G90 I used for my 80M tests stops at 500 KHz,
and none of the consumer general coverage radios I have will do SSB longwave, just AM, in spite of having
SSB on the HF bands.

I'll keep hacking on LF as I have time (and it should go a little better in the winter) but I have the sense it's
more a curiousity than a source of anything practical due to how much effort you have to put in and the
very unfavorable efficiencies for transmitting. On the RX side, it looks like a 6-8 foot loop antenna and an
adequate receiver is all it really takes, and I did NDB SWL DXing back in the 90s with just a Icom R71A and
a long wire and heard stuff thousands of miles away routinely late at night in the winter. On WSPR there's
way more people doing 2200M RX than TX, that's for sure.

ETA:
I just found this manual for a Palomar 1750M AM Transmitter.

Man does bad YouTube video about carrying a Yaesu 710 in a cheap milsurp bag.

A quick Sunday project.

A SOTA beams click to tune kit.  With this kit you press a single button and a 7300 sends a 10 watts carrier no matter where the RF power is set.  The only problem is this kit disabled the internal radio tuner that I need when driving old boat anchor amplifiers.



So, I added a second momentary switch that enables this board when needed and leaves the internal tuner functional.  Kinda crude execution since the second switch was added with parts I already had on hand.

Working on repurposing a 2.4 meter 'portable' satellite dish antenna for use with EME (moonbounce) on at least several of the microwave bands - eventually I'd like to be set up to handle most of the bands from 23cm (a.k.a. 1296 MHz). all the way through 3cm (10 GHz).

The dish was intended to be manually pointed at a geostationary satellite which would be at a fixed coordinate in the sky - however, the Moon does not stay fixed in one place, so I will need to make modifications to support automated lunar tracking in azimuth and in elevation.

I've been working on setting up the base - it's the biggest erector set that I've ever worked with - and I still have more work to do before I'm ready to install the parabolic reflector and one or more dish feeds. Automating the Moon tracking will be an even larger project - but first I'd like to at least get to the point where I can receive Sun noise (and maybe even Moon noise, as well as galactic radio emissions), followed by receiving signals from EME stations, before I'm ready to focus on motorizing the mount, transmitting, etc.

In its current state of incompletion it does look somewhat like an alien spacecraft has decided to land in my yard.

I'm planning to attend the EME conference in Trenton, NJ in a couple weeks, where I'm hoping to meet a lot of active EME enthusiasts and pick up some technical advice from those who are more experienced than I am - I have yet to even receive any signals from the Moon, let alone make any EME QSOs, but I'm expecting that this will be the year when I finally achieve both of those milestones.

I've been making progress, but it's slow, as everything takes longer to accomplish than expected.

More to come in time...

Attached File

The quotes on "portable" look appropriate, that thing looks very, very heavy.

Looking forward to your EME POTA activations using this rig!

Will be watching closely as I found a 10’ dish this weekend for 1296 eme. Going to have to build an LDMOS amp now for my rig. Nice this is I ordered some amp control boards from an open source project and have the source code. It will allow me to modify the code for single band amps and do other things with it. Boards are on the way from the PCB manufacturer and I have the BOM done on digikey to order the components. Ordered 10 boards going to build out 3 of them to start. Thinking about offering them to other people building and maybe doing some amp kits. Anyway I will be following. The guy I am getting the dish from has some linear actuators. Thinking about using some encoders and an arduino with the esp-32 and having the control in the shack with an LCD screen to control it.

Yeah - it is quite a handful for one person to jockey into position - and even though it breaks down into smaller pieces, with the heaviest one probably under 100 pounds, dealing with it has been a bit of a challenge - but at least so far I'm managing.

Luckily the reflector itself is divided up into a central disk with a set of 10 individual 'petals' that link together around the center to form the parabolic shape.

Interesting... I also have a separate 10-foot Winegard TVRO dish that I am also planning to set up for EME.

The amplifiers that I have lined up so far for the various microwave bands are not the most powerful, but based on the reports that I've seen of other small-station setups that have made successful two-way EME QSOs, I should at least be in the ballpark. I have 150 watts out on 1296 MHz, and for 2304 MHz I recently picked up a pair of removed-from-commercial-service amplifiers that I should be able to combine to give me 100 to 150 watts out.

I don't have much in the way of power yet for 3400 MHz. As for 5.7 GHz, I have either an as-yet-untested TWT, or a set of three commercial amps each capable of about 12 watts out, so maybe I can combine those. I don't yet have an amplifier for 10 GHz.

I was expecting that 432 MHz would be my first EME band, but I still have a lot of work to do to get ready on that band, between antennas and the amplifier, so it's looking like I'll be positioned to do either 1296 or 5760 before I'm ready on 432.

I recently stumbled on the satellite portable crowd……. Seems like a solid community. I think the focus is getting a lot of grid squares……. Looked like some digital program similar to FT8, but different maybe. It was kind of a fly-by encounter.

I have seen another ham active on ft8 only once in my grid square. I can be pretty popular at times, and I think that is it.

If you need help with the 432 setup let me know. I made my first EME QSO on 432 with HB9Q and DL7APV back in 2017. Running 4x15el phased array and with a IC-706 and a 100w Brick amp. The 706 was so drifty the fist attempts had too much drift. Had to do the fan mod, and uses a resistor on the LO can that I stuffed with rock wool as it was hard as hell to find the TCXO for that rig at that time. It worked and was able to complete. Now I have the 9700 with the Leo bodnar GPSDO.

By the way where did you get that mount setup? I was going to build one but having something like that would work great as a start point. The gentleman I am getting my dish from also has a 4.2m dish he offered me, but there is some damage to the parabolic. He said it could be repaired. He is the Microwave Guru out here and has built a lot of the Weak signal beacons all around the east coast. I think I will stick with the 3m dish as I have a ton of projects going on at this point.  

From what I am seeing with a large dish and and 50w is all that is needed really to completed. On 10g lot of people running 3-5 watts work a lot of guys. May look at doing the Demi 60w amp mounted to the back of the dish to start out. When it comes to eme there is no such thing as too much power.

Take a look at VSCode and try to get setup with that. You can sync with Git Hub and with the AI they have if you have an Idea on what you want to do, but not sure where to start it helps tremendously. Programmer from work helped me get setup with it and it is great. You can also take your INO files and ask it to convert them to other formats for ESP-32 and other boards. Great program.

I bought the dish/mount along with a bunch of 5.7 GHz parts and pieces from a ham who had gathered those parts over the years, but decided that he had too many other projects to work on.

The manufacturer was Global SATCOM Technology, and it was called the "Model GST-2400-MK Ku-Band 2.4 Meter Fly-away Earth Terminal" - I got it minus the RF equipment. The operator's manual has a 2004 date on it. I haven't quite figured out how I will be driving it in az and el - I have some hefty linear actuators, one of which I will probably refurbish and use for elevation - and I have a gear motor that I may use for azimuth, but have not yet figured out a drive system and encoder to give me the desired pointing accuracy and holding power.

I have been planning to use a 1-meter Ku band dish that I bought on eBay for 10 GHz, but I might try the 2.4 meter dish on that band as well.

As for 432, I have four super-long-boom M2 XPOL yagis that I bought used and need to refurbish. I will put them on an H-frame and mount it on a low tower, and will probably start out by using a single linear polarization rather than either setting up relays to switch between horizontal and vertical or wiring it up for CP.

I also have a K2RIW amplifier for which I need to build the HV power supply (I have most of the parts, just need to focus on getting it built).

As far as frequency stability is concerned, I have a HP Z3801A GPSDO which supposedly works, although I haven't fired it up yet. I have a couple of the DEMI 10 MHz reference signal distribution amplifiers, which I will use to stabilize the transverter LO's. But I have not yet given any thought to my I-F rig's stability at 144 MHz. I have a choice of rigs for that band. I'm probably going to go with my IC-705 (although I haven't yet looked into the possibility of using the GPSDO with that rig).

At the moment I'm troubleshooting a problem with my DEMI 1296 transverter that seems to be related to the 10 MHz OCXO that it is using - it is putting out some strange wideband noise that I hear on the 144 MHz I-F, including a strong glitch in the noise that repeats every 30 seconds - wondering whether it may be the frequency synthesizer that provides the transverter's LO losing its phase lock or something. I've checked it on a spectrum analyzer but so far have not isolated the source of that problem.

Always plenty of projects here to keep me busy - nothing is ever simple

@KB7DX OMG I do remember that! I am still working on that multi band tuner for the input side of the HF amp. Every time I sit down to solder in the coils I get a call from downstairs..lol

I will post some pics soon.

Attached File


Got the amp control boards in. Going to be working on the code a bit to customize the interface. Should work better than the board I currently have. Also want to make some control boards for mono band amplifiers. Need to order the components to put a couple together and sell off the extra boards. There is not much out there for control boards that offer as much as these do so want to be able to provider them to people that home brew. Open source hardware and software. Board control has a teensy 4.1 at its core, and an ESP-32 that will be used for remote operations and custom interfacing. Like the fact that it has Band Decoding with Voltage built in, CIV, and rotary switch decoding. Also has the ability to use a universal band decoder as well. Has all the normal protection and the ability to monitor 4 different temp probes. SWR and over power protection for the input, LPF and antenna. Really cool system and I hope to contribute to that entire community that has been working on this.

I was not familiar with that project or board - a quick search brought me to a github page for an Arduino nano version - but where are the discussions going on about this version?

https://github.com/s21rc/SSPA-Controller-REV3

https://s21rc.net/s21rc-sspa-controller-hardware-rev-3-0/

Attached File


Here is the DX world board versus the ver 3.0. The DX world board is based on the S21rc SSPA controller V2.1 Lite so very limited but very functional. Once the coding for the V3 ESP is done it will be very similar to the B26 from RF-kits.de as far as controls go. Next batch of boards once the first 2 are completed and debugged I will be ordering and having the SMD parts done at the board manufacturer. Plan on using them on all my future amp builds and providing kits of them on my website, QTH, QRZ hamfest for other amp builders. I think it covers all the bases and with 2 controllers its kind of future proof. Excited to see how it can be used over ethernet and Wifi.

Ah, thanks...

I have too many unfinished projects as it is, so I'm not ready to jump into another one, but it's good to at least be aware of this item.

I do have a few flavors of the Teensy waiting for me to play with them (but I'm not sure whether I've got a 4.1 or a 4.0).

And more flavors of ESP-32 dev boards than any one ham should be allowed to have.

Similarly, I've been aware of Nextion displays for a long time, but have so far resisted getting one to play with, due to insane levels of "project overload".

Someday...

Retuning the L3 Harris cross dipole antenna for ham radio bands (40/80). Then got a massive headache. Hopefully will have it done maybe setup for the tuesday ssb net.

Please enjoy this underwhelming photograph.

Attached File

That's a seriously nice crimp.

Got back from Berryville and found some good stuff. Lots of small parts and a nice haul of Heliax and grounding kits for the coax and a bunch of Polyphasers. Also found a Vectronix 2.5k dummy load for the LDMOS amp build that will be needed to test with. Scored a Spectrum Analyzer in unknown condition from an SK estate for $25 so I figured it was worth the chance.

Attached File


Attached File


Attached File


To my surprise:
Attached File


So this am I am going to pick up my 2.4m dish for 1296 EME.
Attached File


This is a project that is going to take a bit to complete, but should be fun.

Nice haul indeed…

Have you given any thought to what you will be using for the 1296 dish feed?

I will be looking for advice on that subject while I am at the EME conference this coming weekend.

Yes its will be a Circular polarized feed. I may get some help building one or may end up buying one, I have not decided. There is a couple of ways to do it.

https://www.rfhamdesign.com/products/dish-feeds/septum-dish-feed/index.php

I have looked at this one. I may try to build one like this. I lack some of the equipment to tune them the right way, but the local microwave elmer here has VNA up to 24hz so I can get some help there. Lots of designed here. I like the ones that do not use the couplers and relays to reverse the feed for RX. Since that induces losses in the system. But I still have a ton to learn when it comes to Microwave work. On the 10g system I will be working on the transverter and amp will be mounted at the dish and use a waveguide and feed horn system.

Testing out an idea...

Attached File


Last 2 pieces of the big amp are on the way. Should hopefully have it on the air in the next week or 2. This will be completed with the 1 pallet first then be completed with the second pallet later. Got the boards in for the QRP 100w LDMOS amp. Have the RF board, the TX/RX with SWR/Power Bridge. And the 7 band low pass. This should be a fun one that I plan on running a DC to DC buck converter on to run off of 12v. Later I plan to build a 600w version using MRF-300 devices for mobile operations.

Second part of the amp project is progressing.

Attached File


This little thing is amazing. This will be able to drive my amp to full legal limit. Got this part done.
Attached File
So I will be able to sample the output of the amp and feedback a signal to use Puresignal digital pre distortion. Plan on making a Variable sampler inside the amp for DPD. Slowly coming along. Have a lot of work ahead of me. Once the Amp is done, the new V3 control board will be built out and debugged and swapped out with the current control board prior to the second pallet coming online. That way I will have the temp monitoring for both pallets. Plan on doing some work on it today.

On a side note went to a small crappy hamfest yesterday. Was able to score an Old Ken Pro AZ/EL rotor for 50 bucks. This is the same as the Yaesu G-5400 made by Kenpro. Looks to be in good shape. My buddy later found the control box in a junk box the guy had and snagged that for 20 bucks.

Old project but working on refreshing due to needs.

Basically, open up an MCS2000 control head, take out the board and replace it with this one and it becomes a Micom HF control head.

Attached File


Attached File


Attached File


Attached File

Be very cautious with variable samplers in this application. They make it far too easy to generate a feedback signal at levels that can damage the receiver. Using a fixed attenuation sampler is much safer.

So the reason for the variable is to be able to tune the pure signal input. But I do agree it is a bit risky. The one I built last week is a variable from 38db to 69db. My plan is to run it on my scope first to check the peak to peak. But I may just use this variable to find the best attenuation needed and make it a fixed sampler inside the amp for the Pure Signal feed back to the hermes lite.

Have you seen the tacked threads here?

Attached File


L3 Harris cross dipole converted to 40/75m resonant legs.

Shortened the long legs to 40m and stitched in wire on the short legs to make them 75m. Fun little antenna to play with.

Before the conversion it was resonant on 10m by happenstance and got North Cook Islands on SSB and 40W. Lol

Excellent resource. Thank you for that. Looks like the variable attenuator I built is almost perfect for it. Except I could forgo the coupler without the the voltage divider circuit. If I can even use a 50db out of the gate it will work fine. I could always pad it a bit going in. I was reading how the radio can do pure signal by using crosstalk without an amp and that you have to over power that signal with the coupler.  I can use the variable on the high setting to get it dialed in at my highest output power and then just replicate that divider circuit for my internal amp sampler. If I run that sampler from the pallet output before the multi antenna relay it will not be used in bypass mode and I can use pure signal with or without the amp.