Coax Jumper Tester

     This is a Coax Jumper Tester for testing those short lengths of coax cable that we ham radio operators use to connect our equipment such as connecting the radio to the tuner, the radio to a coax switch, the radio to an oscilloscope, etc.  Testing with a multi-meter can be difficult because the alligator clips on the test leads tend to fall off very easily and they don't provide a solid connection.  This tester eliminates that problem and gives you a more complete test.
     Operating this unit is quite simple.  Take the coax jumper that you want to test and screw the coax connectors to each of the two connectors on the front of the box.  Connect the red/black zip cord to a 12 VDC power source.  First, flip the power switch on, then flip the test switch to the UP position.  This tests the center conductor for continuity.  While this part of the coax is under test, wiggle the coax to see if the indicator light blinks or flickers.  If it does, then you have a bad solder connection.  If the light remains solidly on, then your solder connection is good.  Now flip the test switch to the DOWN position.  Again, wiggle the coax around and see if the indicator light flickers or blinks.  If the light flickers or blinks, the solder connection is bad.  You will have to repair the bad solder connection on the jumper then test it again.
     Here is the list of components:

2    SO-239 chassis-mount coax connectors
1    DPDT toggle switch
1    SPST toggle switch
2    12 VDC incandescent pilot lamps (You can use LEDs if you like.)
1     Fuse holder
1     3-amp glass tube fuse
1     6 x 4 x 2" plastic project box
3 ft.  #18 red/black zip cord (You can make the cord as long as you need.)
5     6-32 x 1/2" Philips head screws
5     6-32 nuts
Various lengths of #18 hook-up wire
4     red fork terminals

     This blogger does not accept PDF files, so I had to take a photo of the schematic in order to get it posted. 
     Your comments and suggestions are welcome.

73,

John Gercken, AA9UF

Getting Back To CW After 8 Years.

     For many years I had doggedly kept trying to improve my skills as a CW (Morse Code) operator in Ham Radio.  It seemed that the more I practiced the worse I got at copying.  Sending was not an issue, but my copy of anything beyond 12 wpm was beyond what my feeble brain could do.
     I did manage to pass my 20 wpm code test to qualify for my Extra Class ham radio license, but it took 3 tries to get there.  I finally passed on the 3rd try.  After jumping that hurdle, I never tried keeping up the 20 wpm speed because I was just not comfortable copying at that speed.  My brain was just not wired for it.  I tried some QSOs at speeds approaching 20 wpm but I felt exhausted once I got done.  I thought to myself..."Is why we say we "work" a station?  This is not my idea of fun!"
     So, I went back to my old comfortable speed of 12 wpm.  Much to my chagrin, I kept running into high-speed operators coming back to me at the speed of light, expecting me to copy.  I refused to even try and either signed off or went to another  part of the band.  Sometimes I would say "NO QRS, NO QSO." but they still came back at their speed of light, ignoring my request.  At one point I even joined a CW club called FISTS who claimed that they would slow down for slower operators.  I quickly found out that they fell into the same bad habit of creeping up to the speed of light just like all the other hot-shot operators.
     In frustration, I finally sold all 3 of my CW keys and automatic keyers and concentrated my efforts in the digital modes such as PSK31, RTTY, Feld Hell and whatever others I could find on the air.  I was a much happier camper.
     But now, things have changed again.  My oldest granddaughter, Julianna, age 9, is studying for her Technician License and seems to have a keen interest in CW.  Well, like a good grandpa, I bought her the MFJ Morse Tutor so she could practice.  Since I had been CW-free for 8 years, I knew that my CW skills were pretty rusty by this time.  So, I bought a Vibroplex iambic key and started listening to CW signals on the air and I did some keying with the rig power turned way down and the tuner on the dummy load setting to get my fist and brain used to the idea of CW again.
     I decided that the best thing to do would be to stay the hell out of the Extra Class portion of the CW band on 40 meters.  That way the chances of me running into a speed-of-light operator would be minimized.  So far, after 4 QSOs, I have been pleasantly surprised and pleased at my progress and I actually ENJOYED it! GASP!  I have no intention to attempt 20 wpm, tho.  I will stay right where I am comfortable.

A Better Way To Anchor The MFJ-2990 Vertical Antenna.

     I have 2 of the MFJ-2990 Vertical HF antennas and here is my method of anchoring them.  First, I use the MFJ-1903 Tilt-Over base.  This allows me to raise and lower the antenna without any help.  Don't try to raise it by trying to balance it vertically unless you have a second man to help position it on your mast.  Using the Tilt-Over base is the way to go.
     Here are my suggestions on guy ropes.  Use 3/16" black dacron rope.  Tie one end of it at an anchor point about 2/3 of the way up the antenna.  Tie the other end to a clothes line rope tensioner

     Next, I inserted a carabiner into the end of the screen door spring and attached the carabiner to the rope tensioner.  At the bottom of the screen door spring I looped a 4 ft. length of 1/8" wire rope through it and fastened it with small u-bolts specifically made for wire rope.  At the other end of the wire rope, I looped it through the ring on the anchor stake and secured it with u-bolts.

     Why do I use the 4 ft. of wire rope?  I have had rabbits, birds and even mice chew through the dacron rope if it is tied at the ground stake.  The critters can't chew through stainless steel. I have seen Robins peck at the dacron rope thinking it is a worm.

     This is the anchor that I use on the antenna.  It is available from DX Engineering.

    This is a close-up of the tensioner and spring assembly.  This setup works well because the spring keeps tension on the rope and also lets the vertical sway in the wind to some degree.  In the past, I had problems with guy ropes breaking when the wind got too strong because the antenna would jerk on the guy rope.  The spring prevents that from happening.

     One little tip...an easy way to thread the dacron rope through the tensioner is to take a piece of #12 copper wire about 8" long and make a 1/4" diameter loop in one end, just enough to get the dacron rope through.  Don't tie the dacron rope to the copper wire because the knot will not go through the tensioner. Poke the end without the loop down through the top end of the tensioner while keeping a hold of the end of the dacron rope to keep it from slipping through the loop on the copper wire.  You might need a vice-grip to grab onto the copper wire and pull it through.

     Adjusting the tension on the rope is easy.  To make it tighter, just pull the rope through the tensioner.  To loosen it, pull on the insert inside the steel loop of the tensioner to release the tensioner's grip on the rope.  The rope is held in place by 3 ball bearings in the top of it.

     The only downside of the tensioner is that the ball bearings are not stainless steel and tend to rust.  I don't know how hard those bearings are to remove, but I would like to find some stainless steel bearings to replace them with.

73,

John, AA9UF