Welcome to the N3SDO Beacon and general ham radio stuff webpage. A place to keep some of the musings of a mad ham radio operator...

N3SDO Beacon 28.219 mhz

Transmit site, Rienzi Mississippi USA. If you hear this beacon, please Email your reception report. Please send to my callsign@yahoo.com Thanks!

( I'm trying to NOT make it easy for spambots )

73 DE N3SDO

If you are looking for Arduino code examples, go to top left of this page, and click on the 3 horizontal bars for the menu. or click here: sites.google.com/view/n3sdo-beacon/micro-controllers-pll-freq-synth

28.219 Mhz, 5 watts into a ladder line J-pole 1/2 wave vertical antenna with the choke 1/4 wave from feed point.

This beacon project began when a coworker gifted me a Uniden HR2600 10 meter radio from an estate sale. The previous owner had tinkered it killing the transmit in the process. During the Covid19 lockdown, I fixed it, and added a microcontroller to turn it into a synthesized CW beacon. After moving to Mississippi, I have more space and a 40' triangular tower with a PVC sidearm holding the transformer and feedpoint of my Off Center Fed 80-10m Dipole. Eventually the end fed 1/2 wave vertical should be back together and installed on a 10 foot pole on my car port.

So who will hear it? The band is hopping in October of 2024. When I had it operating near Pittsburgh PA, it was heard as far as Italy in 2023. Now in '24 with the sunspots up, I suspect it will be heard even further!

The rig

Uniden HR2600 repaired and tuned down to 5 watts CW to avoid getting really hot operating with a 24/7 duty cycle.

The "NEW" controller

The new controller is a Cypress / Infineon CY8Ckit-059 that I wired into the radio 5v power supply, PTT and Keying circuit. I have it programmed to send CW all over the world. Btw, there is an "Easter egg" in the beacon message.

The power source

We had some 12v 10a AC to DC switching power bricks at work that were being scrapped. Rather then hitting the dumpster, I converted a couple to 13.8v by changing a feedback resistor in the voltage regulator circuit.

The antenna

A ham's favorite thing to tinker with! The current antenna is a 10m J pole with 1/4 wl of the coax being allowed to radiate in collinear phase with the choke coil 8 ft away.

The prototype feed for the 1/2 wave, a ringo inspired 1 turn loop between ground and the antenna with a sliding feed point. Turned out to be too flimsy.

Here is the same amount of wire wound into a coil for better mechanical stability.

A side view of the antenna with the test feedpoint alligator clip. Now replaced with a bolted clamp.

Another view of the 1/2 wave end fed matching coil. I squeezed the turns together to center it on frequency.

The 40 foot tower at my QTH in Rienzi Mississippi. Purchased used from the internet. Rohn 20, the thinner more flimsy TV antenna grade tower so it will never see an HF beam. I build a tilt over base with advice and suggestions from K5WHB using cast iron plumbing parts. It can be tilted over and winched down and up. It currently supports my Comet GP-9 with a 4 foot PVC sidearm with a brass and nylon pulley that some Dacron rope runs through to hoist up my 80-10 meter homebrew OCF dipole.

The tower really is straight and vertically level, its the photographer who's a little off kilter. It also hosts a bird feeder about 5 feet up, its not a weather station or some kind of cool antenna experiment. There used to be a nice tree at the bottom end of the driveway that I intended to use to support the far end of my OCFD, but it turned out to be rotted in the center, and the wind took it down a couple of months ago. I will have to put in a post at the bottom of the yard to support the far end of the OCFD. It will probably host some bird houses too. There are 3 PVC plastic pipe caps on top of the tower to keep the rain out.

I have done a couple of YouTube videos on repairing repeater boards and duplexers. Youtube search : N3SDO.

One of my better videos.

Modifying the USB Simple Spectrum analyzer to get FM modulation from the tracking generator/VFO.

There are a number of videos on tinkering with this spectrum analyzer and repairing and testing duplexers and Hamtronics repeater boards.

Half wave vs 5/8 wave antenna comparison.

This pattern chart shows that the 5/8 should outperform a 1/2 wave antenna. My local testing shows the 1/2 wave at 10ft elevation is better then a 5/8 at 1 ft. Is the height advantage improving the 1/2 wave? I plan to revisit this again and do a more equal test.

Small loop antenna

My prototype was about 6 feet diameter and will tune down down to about 60m, but won't quite make it to 80m. The performance with WSPR is below that of my OCF dipole at 30' (10m) but is quite respectable for being what it is!

The Prototype 2M dia loop

Here is a 6' (2m) ish diameter saggy loop made from an 18 ft piece of damaged coax that the jacket was cut through in several places and could not be used outdoors. Its suspended from the ceiling by a couple of cup hooks and loop fed in the far corner near the wall. The pattern is East-West but favors the East.

My motorized capacitor

The cap was a $5 hamfest find, and the worm drive was recovered from a junked tape backup autoloader. The motor and reduction drive were salvaged from the wheel drive from a motorized floor sweeping robot.

The Bookcase loop idea...?

Can I make a loop around the rear of a book case and make the tuning capacitor into a Fake Book on the bottom shelf?

I have also had ideas of putting the loop on the back of an interior door. That would permit changing loop orientation by opening and closing the door...

And here is your favorite disclaimer. This web page is a work in progress. More to come.

Can I build a nice looking morse iambic key out of wood, ball bearings salvaged from some old PC fans, and some stainless 4x40 screws?

Here is what I made.

The base and key mechanism is oak, adjustable magnetic repulsion provides the tension, and stainless screws provide the electrical contact. The key switches pivot on 4 ball bearings. The wonderful things you can build with a Dremel and some leftover parts and some wood.

Doing some fine tuning of the bearing fitment with my home made carving knives.

A first coat of sealer on the apple wood finger paddles prior to shaping. Look at that grain!

Working out the geometry of the mechanics.

Here is the finished result.

I think it came out pretty good for my first attempt. Now if only my CW skills were better!

The wood key next to the DDS VFO for my Heath SB-104.

I like the SteamPunk effect the brass and wood gives the VFO. The frequency and status is shown on the LCD, but the camera flash washed it out. The recycled Bakelite tuning knob and the rectangular booster amp on the back of the VFO with the brass SMA connector along with the buttons and A/B switch just adds to the Jules Verne coolness factor for me.

Yes the paddles are asymmetrical, I tried to keep some of the live edge on the Apple wood, and it works well the way my fingers contact the paddles.

Speaking of SteamPunk...

I had some old meters, a huge heatsink, some really big azz resistors and 5 large high current Mosfets > MOOSE-FETS!

So I set about constructing an electronic load for testing power supplies and doing AH drain tests on batteries. The load has 2 independent variable electronic load circuits with 1 Ohm 50 watt resistors and high power mosfets in series, then the resistor + mosfet circuits are then in parallel. x3 on circuit 1, x2 on circuit 2.

Each load circuit is variable and switchable, and the 2nd load circuit uses a push button on the top right to engage the load at a separately adjustable current level for generating transient loads to simulate a transceiver in transmit mode.

The PCB with the OP-Amp is not shown in the photos, it controls the FETs in a voltage control to constant current configuration, and adds a variable voltage threshold comparator to disconnect the load for battery AH testing without draining the battery down far enough to damage it.

It also functions as a multiple circuit switchable DC load center since I had a bunch more connections on the terminal strip to use up, and it can function in day to day operation.

Its mostly convection cooled, buy has a 40 degree C thermal on-switch to enable forced air cooling if needed. You can see the reflection of the cooling fan through the lower vent intake holes.

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