Saturday, September 30, 2017

Antennas #1 and #2 Are Now Complete!

Whew!  Who would think such a simple job as building a couple of 2-M antennas could take SOOO long?  Today was another 7-hour day but a major milestone has been reached.  Construction of both antennas is now complete.  whup >  whup >  whup > whup >  whup >  Did you see that?  It was me giving myself a Big High FIVE!  OH, and it hurt - duh!  These things were a whole lot easier 30 years ago.

Today I took Antenna #2 out of the garage and mated the final boom sections.  Then, I installed the Antenna Boom Truss and finally the Boom-to-Mast bracket.  On the right you can see the Antenna Boom Truss while the antenna is balanced on the WorkMate.  I did this so that I could adjust the turnbuckles of the Truss to support the boom of the antenna in a level position.

After completing the work on Antenna #2, I took Antenna #1 down from its resting place on the roof and carried it around to the garage so I could install the Antenna Boom Truss and the Boom-to-Mast bracket on it.  (NOTE:  This was a whole lot easier than putting it up there as "gravity" was working in my favor!)  I continued to use the bar stool to sit on while doing most of this work.  My hip and back are still "complaining" a bit so I've been trying to take it easy on them.  All the hardware was installed using Never-Seez and that added a lot of time to the project.  However, if anything ever needs to come apart, it will do so EASILY!

Once the work was finished on both antennas, I did not want to leave them sitting on the ground for the deer (or a prowler) to step on.  So, I figured I could put them both up on the Fiberglas cross-boom and let them rest on the roof again.  This time I got Evelyn to help me with the project as my back was not really up to trying to man-handle the antennas by myself since gravity would NOT be my friend this time!  I stood on a step-ladder and hand-walked the antenna up as Evelyn brought the back end in toward me.  This worked out well and I was able to fasten the Boom-to-Mast bracket from the antennas to the Fiberglas cross-boom with little difficulty.

BUT - (there always seems to be a "but" in these projects) - I had placed the Boom-to-Mast bracket a little too far toward the rear of the antennas and they were pretty front-heavy.  It will be easy enough to loosen the brackets and slide them up the boom to achieve a better balance point.  I just didn't have it in me to try and do that today.

As I took a photo of the antennas resting on the roof, I spotted the "target" of my project and snapped a photo of it.  You can see that photo on the right.  Click on any photo to see a larger image.

It sure will feel good when I have the antennas balanced and secured to the Fiberglas boom and have the rotors turning them to point at the "target."  Hopefully that time will come within the next week.

Friday, September 29, 2017

Antenna #2 - Nearly Complete

OK, it was a bit of a struggle today but I finally managed to nearly complete building Antenna #2.  After building Antenna #1, I thought this would only take me 3 to 4 hours to complete.  However, that was not the case.  I have been having issues with my hip and that slowed me down a lot today.  I took a bar stool into the garage so I could sit for most of the work while I had the antenna supported on saw horses.

But, besides my hip problem, I found that 9 of the 11 Director elements were NOT marked in the center like those of Antenna #1.  So, I had to measure each element, cut that measurement in half to find the middle, mark it, then mark the edges of the mounting bracket.  This slowed things down a good bit.  Then, while measuring the elements, I became suspicious that the elements (although marked as D1, D2, D3, etc.) were not in the correct order.  The manual does not include the element lengths so I ended up climbing a step-ladder to measure the first 4 elements of Antenna #1 to see if they were the same.  They were.  Once all 13 elements were mounted, I placed both sections of the antenna on the floor of the garage.  You can see what Antenna #2 looks like in the photo above.  Click on it for a larger image.

Having learned a bit from putting together Antenna #1, I decided to not put the boom sections together between the 3rd and 4th sections.  That allowed me to complete the build of Antenna #2 totally in the garage.  All I need to do now is to connect the two boom sections and both Antenna #2 and Antenna #1 will be in the same point of construction.  I did not keep a stopwatch on today's work but I think it took me about 7 hours instead of the 5 hours for Antenna #1.

The next step is to build the boom truss for each antenna and install the boom-to-mast bracket.  At that point, the antennas will be ready to mount on the Fiberglas cross-boom.  Then, I need to tune them and connect up the feedlines. 
Progress is definitely continuing!  Stay tuned!

Wednesday, September 27, 2017

2-M EME Sequencer Modifications Complete

Most ham stations have no need for an external "Sequencer" as the functions of a sequencer are built into the rig itself.  However, it can be an essential piece of equipment for a VHF/UHF station or one used for EME.  What it does is to turn various pieces of equipment ON or OFF in a specified sequence when moving between Transmit and Receive.  This is done to protect some equipment from receiving RF when it is still in receive mode or to protect the transmitter from transmitting before the antenna change-over relay has completed switching the antenna to the transmit position.  Especially when you are dealing with rather high power in VHF/UHF frequencies, NOT using a sequencer can result in serious damage to your equipment.

Take a look at the station equipment diagram above and think about what needs to be turned on (or off) first, second, third and last when moving from Receive to Transmit and back.  If you are in RECEIVE, your LNA is being supplied with 13.8 VDC and the T/R Relay is in RECEIVE.  The Amp is OFF and the Rig is in Receive.  When you press the PTT, footswitch, or the computer tells the system to begin transmitting, FIRST you remove the 13.8 VDC from the LNA to turn it off, then you tell the T/R relay to move to the TRANSMIT position, then you tell the Amp to turn ON, and lastly, you tell the Rig to begin transmitting.  When returning to RECEIVE, all those items need to be performed in the reverse order.  By using a sequencer you can control the order in which all these devices are triggered and you can be sure that the LNA is OFF, the T/R relay is firmly in the transmit position and the amp is turned on BEFORE the Rig begins transmitting.

Many years ago (when planning an earlier EME station) I acquired a Model TRS, TR Sequencer, from Down East Microwave (DEM.)  It was still in the original box in my garage so I had a "NOS" (New, Old Stock) sequencer ready for my current 2-M EME station.  However, I needed to figure out the logic of which piece of equipment to turn ON (or OFF) in what order and how to control that switching.  DEM gives a "matrix" to help you layout the configuration.  There are four sequenced stages each with two separate outputs.  This means you can control up to 8 different pieces of equipment during four different time periods.  The switching time between stages is controlled by an R/C circuit with a user adjustable time constant of about 125 milliseconds.  That means you will have about 1/2 second between transmit and receive (and the reverse) for the full sequence process.

Sequencer Matrix Configuration
I copied the matrix so that I could work on it again and again by scanning it into the computer.  I quickly determined that I needed to control the pieces of equipment shown in the diagram at the top of this Post as well as one other T/R Relay on the Receive line.  That gave me the four sequenced stages and the order of the equipment.  Once that was done, I needed to determine how to control each piece.  For instance, when I wanted the station to be in receive mode, I needed to supply 13.8 VDC to the LNA.  Each stage of the sequencer can control two separate pieces of equipment and can deliver either a High Voltage, a Low Voltage (Ground), or an Open (no contact at all.)  Then, in Transmit mode it can again supply a High, Low or Open to the same piece of equipment.  In this example, the LNA needs a High when in Receive and an Open (no voltage) when in Transmit.  You can see on the Matrix at the right that I have circled the H in Receive and the O in Transmit for the LNA.  (Click on any image for a larger view.)

Inside Sequencer Showing Modification Board on Right
Once the sequence configuration was determined, I needed to modify the stock DEM TRS Sequencer to meet those conditions.  Some of the stock configurations were just what I needed but I had to make four changes to the wiring of the board.  This meant I had to remove the circuit board which was mounted with three nuts to the bottom of the case, remove the power switch plus the ON LED and XMIT LED from the front panel, and twist the board up to where I could un-solder (and re-solder) the connections I needed to change.  Since there were some ELEVEN wires coming from the board to the RCA connectors on the rear panel, this was not very easy.  And, it would have been really helpful to have someone to hold the board in place while I held the solder and soldering iron - Hi!  Still, I got 'er dun!

One change I had to make was to supply a different  High voltage for the T/R Relay than the 13.8 VDC available in the sequencer.  So, I added another RCA jack in an open hole on the back of the sequencer where I can supply the 20 to 28 VDC needed by the T/R relay.  That voltage was internally connected to one side of the second timing stage relay so when activated it would either supply 20-28 VDC to the T/R Relay or remove that voltage.

Sequencer Showing ON Above and XMIT Below
Once the above changes had been made and checked out, I needed to add some circuitry to the sequencer.  My rig (Elecraft K3S) has a provision called TX Inhibit where you can keep the radio from transmitting until the TX Inhibit line is released.  Turning on the menu function of TX INH (Transmit Inhibit Signal) allows you to prevent transmit by holding Pin 7 of the ACC connector Low (or High) through a 2.2-K to 10-K resistor to a 5 VDC supply.  I found a suitable circuit online from KL7UW where I just needed to build a 5 VDC power supply, add a relay, make a few connections and the result would be that the radio would not transmit until the sequencer gave it the proper signal.

I built the 3-terminal regulator power supply and other parts on a small circuit board and installed it inside the sequencer as you can see above.  I also decided it would be helpful to see that this circuit was indeed producing the 5 VDC and that the 20-28 VDC power supply was providing its voltage to the sequencer.  So I added two LEDs to the front panel along with a decal describing what they were indicating.  You can see those in the photos of the front of the sequencer on the right.  The upper photo shows the RECEIVE mode where the sequencer is turned on, 5 VDC is being made by my little power supply (as shown by the Blue LED) and 24 VDC is being sent to the T/R Relay up at the antenna to switch it into Receive mode (as shown by the Green LED.)  The bottom photo shows how the front panel looks when it switches to TRANSMIT.  The 24 VDC is removed so the T/R Relay switches to Transmit, the 5 VDC is still being provided, and the XMIT LED is illuminated to indicate that the sequencer has switched to TRANSMIT Mode.

NOTE: the T/R relay is POWERED ON for Receive.  This is done so that if you should lose power to the relay or the wires get cut or suffer an intermittent connection, etc., the relay will go into the TRANSMIT position and the expensive preamp and the receiver input will be protected.

All that is left now is to run a couple of wires to the K3S ACC Connector and connect them to the appropriate pins on my modification circuit.  Then the LNA, the CX-600NL relay, the T/R Relay, and the amplifier need to be connected to the RCA connectors at the rear of the sequencer.  At that point, the station is ready to turn each piece of equipment ON or OFF in the proper sequence when changing from Transmit to Receive.

Wednesday, September 20, 2017

Building Finally Begins on 2-M Antennas

220 VAC Y-Splitter for 6-M & 2-M amps
OK, Sports Fans, today I began building the 2-M antennas for the EME project.  YAY!

Two 13-L 144-MHz Yagis
But first, last night I built a "Y"-Splitter for my 220 VAC circuit.  I have two large 30-amp 220 VAC outlets in the wall of my shack but felt that it would be nice to have the HF amp plugged into one of them and the 2-M and 6-M amps "share" the other.  So, I built the splitter shown on the left.  Not a hard job but one that really needed to be done because the 220 VAC outlets are behind the operating table and very difficult to reach.  I have to pull out a 2-drawer file cabinet (which has the 6-M and 2-M amps on top of it) in order to reach the wall behind the operating desk.  Not fun!

Today I began the building of the 2-M antennas in earnest.  On the right you can see the shipping tube that contained the two 13-L InnovAntenna 144-MHz yagis.  The two 13el LFA2 2-M yagis were tendered to FedEx on June 29th (of 2016) and delivered to me on July 5th.  That's just 6 days and may have been much less if it wasn't for the weekend and the holiday.  I can't believe how fast InnovAntennas can ship antennas from England right to my house in Hurricane, WV. (Click on any photo to see a larger image.)

Elements Named
Element Center Markings
Once everything was un-boxed and inventoried, I was very pleasantly surprised.  Each end of every boom section was VERY plainly marked as "1", "2", "3", "4", "5", and "6."  Even better, since there were two antennas in the package, one set of booms was marked in Black and the other in Red.  NICE!

Next, each element was plainly marked as "RE", "DE", "D1", "D2", "D3", etc.  WOW!  No need to measure each element to find the correct one.  I am suitably impressed now.

Next I noticed that the elements have three marks near the center of each.  The manual indicates that these marks show EXACTLY where the center of the elements are and the two marks on either side, are spaced perfectly so that you can see them on the outside of the insulated element mounting brackets to know you have the element centered.  (This just keeps getting better and better!)

You can see in the photo on the left how those centering marks work.  When the top piece of the element mounting bracket is installed, the marks on the outside show up nicely so you can perfectly center each element.

The one complaint I have is that the actual written instructions for the antenna leave a good bit up to the builder to figure out on his own.  Luckily I had built an InnovAntenna 6-M beam two years ago and had solved some of those problems.  For example, there is a one metal element mounting bracket (all the rest are plastic) and no indication in the manual of where this goes.  From the 6-M antenna build I knew that this was a grounding bracket for the Driven Element loop.  Things like metric measurements, "P" clips, "RivNut inserts", "Jubilee" clips, and so on can cause some confusion but Mr. Google is your friend in these circumstances.  ("Jubilee" clips are "hose clamps.")

Marks Center Elements
The first thing I did was to assemble the first two boom sections.  The boom is square tubing and there are short pieces of round tube that slide inside the square tubing.  Those short pieces are plainly marked with tape that are numbered to match the pieces of the boom where they fit.  During manufacture, they were drilled in those locations so there is no problem in lining them up.  Yes, the short round pieces are also marked in Black and Red to denote the two separate antennas!

Never-Seez on Boom Joints
I coated the round pieces with Never-Seez and they slipped right in place.  Just as I had completed the first joint, Bob, W8OM, stopped by to drop off a contribution to VK9MA.  He noticed (as I had noticed) that the two square boom pieces were not perfectly aligned.  I said I could take one off and turn it around but Bob suggested I just loosen both and see if they would twist into place.  Yep!  That did it!  Bob's 'da Man today!

After the boom pieces were in place and supported on plastic saw horses, I began the process of installing the elements.  Since the elements were labeled and the centers were marked, this process proceeded at light-speed.  I just laid down one of the element clamp halves, placed the element on it, put the other half of the clamp on top, smeared some Never-Seez on the end of the metric Cap Bolts, and screwed the bolts (with an Allen wrench) into the "RivNut" inserts that were already installed in the boom.  Notice there was NO MEASURING to figure out where to mount the elements.  The "RivNut" inserts were already in the boom and I just had to screw in the bolts.  Easy-Peasy! 

 I found that I could pick up the two halves of the element clamp, two cap screws, the next element, smear on the Never-Seez and install the element in about 3-4 minutes.  It went SO fast I was getting dizzy!  I did double (and triple) check the element names to make sure they were in the right order as well as the centering marks.  Before completely tightening down the elements, I placed a large metal square alongside the boom and made sure the elements were square to the boom. 

Antenna #1 Nearly Completed
Never-Seez on Bolts
The driven element loop took a little longer to install as there is a C-shaped piece of tubing that slips into each side of the two DE ends.  This is held in place with "Jubilee" clips (hose clamps.)  And, the measurement from the inside of one "C-end" to the inside of the other is nominally 908mm.  I have a carpenter's rule that is marked in mm so that made this part of the project simple.  Adjusting the length of that loop by sliding that "C-piece" in or out is how the antenna is tuned.  This will need to be done with the antenna in its operating location at a later time.  I also used Never-Seez on mounting these "C-pieces" to insure good conductivity and prevent the metal from seizing over time.

There is also a "Truss" assembly that I need to construct and install to support the 26.26-foot length of the antenna.  Also, the boom-to-mast bracket needs to be installed.  This was not done today because it requires balancing the antenna and I'll leave that for another day.

So, today was a VERY good day on the EME project.  Antenna No. 1 is pretty much complete.  Building Antenna No. 2 should go a little faster now that I have a work flow established and all the necessary tools in place.  I carried the antenna around to the EME tower and just laid it on the roof so that the deer won't trample it in the yard.  Hopefully we get no strong storms before I finish the mounting - Hi!

Monday, September 4, 2017

Serial PTT Circuit

In the spring of 2009 I purchased N8LP's LP-Pan Panadapter and needed a better computer in order to run the SDR programs like NaP3 which could utilize that hardware.  I decided I would build myself a speedy computer to do just that.  I researched and purchased all the parts necessary and then on July 3rd I broke my right leg really bad.  I was in a wheelchair for 4 months after spending about 16 days in the hospital.  During all this the computer parts just got shoved under the bench and left there for about 7 years!  Recently a friend put it all together and I have a nice (essentially new) XP Pro SP3 computer with 4 GB of RAM. Since XP is really not supported anymore, I decided to utilize this computer for my digital operations thus keeping those separate from the computer I use for Internet surfing, email, etc.

Serial PTT Circuit
In setting up that newly-built computer to do this, I find that I need some way to allow that computer to key the PTT of the Elecraft K3S.  My normal station setup has the microKEYER II connected to the K3S and the Windows 7 computer.  So, I purchased a 2-port Serial PCI controller card and installed it in the XP computer.  That gives me two COM ports that I can use for various things - one of which will be to key the Footswitch input of the microKEYER II.  This will cause the K3S to go into transmit when the WSJT software wants it to transmit.

Completed Wiring of the Circuit
A little searching on the Internet found a suitable circuit (shown on the left) and I only needed to acquire a couple of diodes and a transistor to build it.  Luckily there is still a Radio Shack outlet in Kanawha City and they had an MPS2222A transistor and a pair of 1N4001 diodes in stock.  I already had the resistor, the DB-9 plug, and the cable in my junk box.

It did not take much time to wire up the parts and you can see the completed Serial PTT circuit on the right (click on any image to see it larger.)  I chose to use the RTS line but I could have used DTR just as easily.  I only need to tell the WSJT software the COM Port number and click on the RTS button to allow the software to communicate with the microKEYER II.

A quick check of the circuit by telling the WSJT program which COM port to use and plugging the cable into the Footswitch input of the microKEYER II and, VOILA!  I can now key the K3S from the newly-built XP Pro computer - SUCCESS!