Coax Stub Filters

11/04/10 —  Installed the final 2 coax filter stubs:  a CS-1 on 80m and a CS-9 for 160m.  Here’s what the installation looks like in the antenna switching shed.

Coax Stub Filters installed at SixPack on antenna ports:

    * 10 meters – CS-6 (1/2 WL-open 10m) & CS-4 (1/2 WL-open 20m)

    * 15 meters – CS-3 (1/4 WL-shorted 40m)

    * 20 meters – CS-4 (1/2 WL-open 20m) & CS-5 (1/4 WL-shorted 20m)

    * 40 meters – CS-3 (1/4 WL-shorted 40m) & CS-7 (1/2 WL-shorted 15m)

    * 80 meters – CS-1 (1/4 WL-shorted 80m)

    * 160 meters – CS-9 (1/4 VL-shorted 160m)  

10/23/10 — More work on stub filters.  Added CS-3 and CS-7 to 40 meters.

Tested to determine cross-band interference.  I used the lower C51XR for all 10, 15, 20 & 40 tests, and used both the 80m shunt tower and the 80m dipole on both transmit & receive.  Transmit mode CW, power out 1.5kW. Receive mode CW, filters 6.0kHz.

Here is the matrix:  

RIGHT RADIO RX BAND1015204080160
10X<S0<S0, avoid harmonic>S9+50<S0, avoid harmonic>S8nilnil
15nilX<S0, avoid harmonic>S8nil, avoid harmonic>S9nilnil
20nilnilXnil, avoid harmonic>S9nilnil
40nilnilnilXnil, avoid harmonicnil
80nilnilnilnilX<S3, avoid harmonic >S9+20

These results pleased me for first attempts at coax stub filters.

10/19/10 — Continued working on stub filters.  Added CS-5 to 20 meters, and installed CS-6 & CS-4 to 10 meters.

10/16/10 — Found burnt barrel connector in top 20m antenna feedline (it had to be 120 feet off the ground).  Replaced it and corrected the intermittent high SWR on that antenna.

10/06/10 — Tilted over Tower #3 and realigned the cubical quad to correct its heading.  It slipped on the mast during a storm last year.

09/29/10 — Began building and implementing coax stub filters on the output of SixPack #1 to Tower #1.  I have MUCH to learn in this area.  Using an AIM4170, I cut two pieces of RG-213 to 1/4 WL at 7.150 MHz.  One I made into a CS-3 and installed on the 15 meter port of the SixPack, and the other I made into a CS-4 and installed on the 20 meter port of the SixPack.

For reference, I’m using Managing Interstation Interference 2nd edition by W2VJN as well as K1TTT’s online Technical Reference and his online copy of K2TR Coax Stub filters article.  I used the K2TR drawing, and cross-referenced it to the table on page 46 of Managing Interstation Interference .  Here is the drawing, with the notations from page 46 superimposed.

Now I have to get more RG-213, more UHF ‘tees’, and spend more time learning and tweaking!

Another good source of info is “Some Q&A About Coax and Stubs for Your HF Station
By Jim Brown K9YC

Shunts and Beverage antenna system

09/25/10 — Finished the last of my 4 beverage antenna by installing the wire for Europe.  Worked on a sticky relay in the antenna switch.  Cleaned up the shack a bit, as a first step toward the CQ WW group’s arrival late next month.

09/20/10 — Built a Magic-T splitter for the beverage antenna system.  Installed an A/B relay to select either the 80m dipole or 80m shunt fed-tower.  Replaced the RF bypass capacitors in a lightning damaged SixPack.

Went through my paper QSL cards to update my DXCC totals, and found several new ones that I will send to ARRL HQ.

09/16/10 — Completed tuning the 80 meter shunt feed.  My goal was to have it resonant at 3.6MHz.  I think I was pretty successful with the tuning.  The shunt wire is spaced 36 inches from the tower, and the shorting bar is about 27 feet up.  

09/11/10 — Installed the permanent shunt feed system on the tower.  Built the necessary standoffs to mount the vacuum variable cap in the tuning box.  Assembled everything with copper strap for low inductance.  Silver soldered 4″ copper strap to the ground ring at the tower base and connected to the base of the tower as well as the coax shield on the shunt feed.  Used an AIM 4170c to get baseline readings.  It looks like I need to raise the shorting bar about 12 to 15 inches up the tower.  It will have to wait until next week.

09/10/10 — Completed the beverage at 270 and 315 degrees.  Installed antenna switch at central beverage switching point.  Installed F connectors, and hooked up a receiver.  Gave it a try.  Heard BU2AQ at 1045 UTC on 80m.  Could not even discern any signal there if listening on the transmit dipole at 75 ft.

09/06/10 — Continued to work on beverage antenna system.  Figured out a way to also have a 480 ft beverage at 90 degrees.  Set more 4×4-12 ft posts.  Built 4 transformers using the W8JI design.  Buried feed line to all 4 beverage feed points.  I sure like the radial burying plow!  It is coming in very handy!


09/05/10 — A very pleasant surprise!  KG5VK paid me a visit this afternoon.  As a first-time visitor, I gave him the nickel tour.  Then we talked multi-op strategy.  I’ve got several items to do in and around the station now!

09/04/10 — Began the expansion of my beverage antenna system.  Set several 4×4-12 ft posts.  Strung 800 ft beverage at 270 degrees and 485 ft beverage at 315 degrees.  Cleared underbrush to extend former 285 ft with goal of at least 500 ft at 45 degrees.  Still have to construct the transformers and place the ground rods at both ends of each beverage.  Used my radial plow and buried feedline & control wires from shack to central beverage switching point.


With help from K5RUS, we also worked on shunt feed on tower for 80m.  Still in experimental mode – we did locate the approximate feed point and determined approximate capacitor value.  Now I’m ready to build the final tuning assembly and secure the shunt wire more securely to the tower.

Also sanded and applied 2 coats of polyurethane to desktop for multiplier operating position.  Replaced feedline from multi position to antenna switch shed.

08/30/10 — Finally repaired my TopTen Band Decoder/Yaesu with source driver mods.  It was damaged in the May 2009 lightning fiasco.  I just had not made it a priority.  It is now on Radio 1 (left), and automatically switches the ICE 419 bandpass filter between the FT-1000MP and AL-1500, and the SixPack for antenna selection.

08/28/10 — Finished burying radials this morning, with a total of 40 radials, most about 125 feet long. A few had to be shorter. In all, used 5,000 feet of wire.  Silver soldered the radials to the ring of #4 solid copper wire around the base of the tower.  Installed the shunt wire up the tower to 75 ft, and put the shorting bar at 36 ft.  Now I have to build the tuning network and put in a weatherproof box.

08/26/10 —  Buried another 16 radials this afternoon.

08/25/10 — Began burying 1/4 wavelength (~125 ft) radials around my 120 ft tower.  Got 14 done (1,750 ft of wire).  I’m installing 36 radials, 10 degree spacing.  The ends of the wire are 21.6 ft apart.  The goal is to shunt feed the tower on 80m and 160m.  This project began with the purchase of 5,500 ft of 12 gauge solid THHN wire and 2 vacuum variable caps at Dayton in May.

08/23/10 — Modified my middle-buster plow to be a radial/cable burying plow, complete with wire roll holder and dispenser tube.  It only took about 2 hours .




Spring Construction and Work

Late May — Aquired a spare 8877 “pull” for the AL-1500.

Dayton 2010 — I made the trip with K5ER and KC5WA.  I always enjoy the fleamarket and Mendelson’s downtown.  Attended CTU for the 4th consecutive year.  Won the CTU eyeball sprint, edging out N9NB by only a few points.  Enjoyed Wed thru Sat nights in the Contest Super Suite.  Attended the 18th annual Contest Dinner; congrats to Louisiana Contest Club member Don Hill AA5AU for his induction to CQ Hall of Fame.

I always seem to bring home work from Dayton.  I bought the ‘stuff’ to: 1) shunt feed my tower on 80m and 160m (vacuum variable capacitors, 5,500 feet of 12 AWG for radials); 2) enhance my beverage receiving antenna system; 3) continue streamlining control cabling in the antenna switching shed;  and 4) be LOUDER and HEAR better!

05/08/10 — Today I installed the frame and bearing portion of the 1st TIC ring rotor at 85′.  My C-31XR will reside on it.  Looks like it will get completed sometime after returning from Dayton.  

04/14/10 — I pulled control wiring for the 2 new TIC ring rotators thru conduit from the antenna switching shed to Tower #1.  Also made up the cables from the shed to the shack.

Station Building Continues

02/28/10 Constructed my first beverage antenna.  It is 285 feet, oriented at 45 degrees.  Average height above ground is 5 feet.  My homebrew feedpoint transformer is of ON4UN design on a FT-114-43 core.  I used the design from the 3rd edition of Low Band DXing by ON4UN as found on page 7-16, figure 7-17.

Now only time will tell if it works!  Right now at 23:32 UTC on 28Feb2010, I hear EA6DX calling CQ on 3.506.


02/23/10 — Made a deal to acquire (2) Tic Ringrotors model 1022D.  Now I’ll be able to rotate the lower 2 antenna!  I hope to get them on the tower before really hot weather gets here.

K3 upgrades!!!

01/30/11 — Placed an order with Elecraft for 1.8kHz and 250Hz 8-pole filters for the K3.  Should receive them at weeks end.  I plan to go with 2.8, 2.1, 1.8, 400 & 250 8-poles in the main receiver.  I’ll have a 13, 6, and 1000 on hand as well.

Coasting the rest of May

05/30/09 — Installed coax to top C51XR; installed power and control wires to M2 Orion 2800.  Tested rotator- it appears to have survived the lightning strike.  Also tested all feedlines, control lines, etc. – all test OK.

05/26/09 — On Tuesday May 26, the station was severely damaged by a lightning strike.  Apparently entering via the AC power mains, very little gear that was interconnected survived.  As it turns out, another ham ½ mile down the road took a direct hit on his tower, which appears then to have back fed thru his solar power/battery inverter system and then to the power transformer to his home then down the lines toward my home.  


05/25/09 — Installed connectors on shack end of hardline.  Installed SixPack.  Installed terminal strips for control wiring junctions from 4 StackMatches.  Installed feedline up tower to middle C-31XR.

05/18/09 — Installed the new StackMatch, made up the control cables for the four StackMatches.  Climbed up to the bottom C51XR and installed the feedlines in a temporary fashion.  Now need to install connectors on the shack end of the hardline.

05/12/09 to 05/17/09 — Attended CTU and Dayton Hamvention.  Acquired a used AL-1500, another used StackMatch, several connectors, some repair parts for 3 Heil headsets, EZNEC 5.0+.  Participated in the Kansas City DX clubs CW Pileup event for the first time.   

Antenna Party

05/09/09 — Antenna party!  With a group of friends and a crane, we mounted the 3 large Force 12 antenna to Tower 1.  Certainly no one in our group had ever handled antenna as large as the C51XRs.  I thought the crane would be safer and save time – however it was on site for 7 hours.  W5KGT and WX5CW were up the tower first to change out the top section (I had pre-assembled a complete top section with rotator, thrust bearings, guy brackets, and mast.) and mount the top C51XR.  On the ground, we had much difficulty tuning the 40m portion of the 1st C51XR; took 1.5 hours, with the crane lifting and lowering the antenna a couple of dozen times.  We also had difficulty with the crane boom being in the way of the elements as the 2 C51XR were raised and mounted.  The C31XR install was pretty easy.  W5WZ and W5PEM were on the tower to mount the lower 2 antenna – with W5WZ working on a tower for the first time.  A nearby late afternoon thunderstorm brought everyone down the tower before the feedline could be run. 

05/04/09 thru 05/08/09 — Wow!  What a week!  Many final finishing touches from gathering final nuts and bolts, assembling comlete top section, installing last PL259s, installing baluns, assembly of 40m sections of both C51XR, verifying lengths of coax for the up the tower runs, gathering tools, electrical tape, etc, etc ad nauseam.  I did the very best that I could to plan ahead so the install would be smooth.

05/03/09 — Climbed a tower for first time – my tower – to the top!  Assembled 2/3rds of the C31XR.  Made a mast plate for the C51XR boom truss cables.  Made 2 plates to sidemount the C31.  Met with a crane company foreman to evaluate the antenna raising next Saturday.  Found a broken element tip on one C51XR – will order tubing tomorrow.  Wound the final 15m helical hairpin.  Assembled the last balun for a F12 antenna.

05/02/09 — Helped take down my F12 C31XR from a tower at K5ER and put my KLM KT34XA up in its place.  The C31XR will reside as my middle antenna at 85′, locked down to Japan.

April – T-minus 30 days until antenna stacking

04/25/09 — Assembled 11 LMR400 flex coax jumpers for rotator loops with PL259s.  Installed baluns on first C51XR.  Primed and painted mast.  Fit the boom-to-mast cradle to the top C51XR.

04/23/09 — Pulled control wiring in conduit.  1 – 12/2 UF; 4 – 18/4 w/grd; 3 – 18/4; 2 – RG59, a total of 2,000 feet of control wire.

04/18/09 — Cut 11 lengths @ 125 feet of LMR400 type coax for my StackMatch feeds to the antenna.  Installed PL259s on one end of each cable, using the K3LR method of soldering the shield to the connector body. During the past week, I’ve continued gathering the myriad of bolts & nuts, truss cable, electrical tape, etc. that we will need to install the antennas.  I borrowed an AIM4170, swept both antenna on 10, 15, & 20 — they do look and perform in a reasonable manner, considering they are only 3 feet above ground.

04/06/09 — Assembled the second Force 12 C-51XR.  Now both C-51’s need the 40m linear elements installed and tuned, all 4 bands baluns and feed lines installed, 20m driven elements lengthened for separate feedlines, and the truss cables inspected.  Then, a thorough inspection of each antenna, and they will be ready to fly!

04/05/09 — Installed three StackMatch relay boxes in telco pedastal box at tower base.  Parked M2 Orion 2800 at 0 degrees with South stop.  Installed studs in 2800, grade 8 bolts in mast clamp.

04/04/09 — Assembled the first Force 12 C-51XR, and laid out the parts for the second one.  The antenna party is getting really close now!  My daughter painted the 3/4″ plywood in the antenna switch shed.

Two Busy Months


3/28/09 — Pulled and pushed six runs of 1/2″ hardline through the 200 feet underground 4″ conduit to tower. Modified telco pedastal box to support StackMatches.  Prepared 4″ conduit between pedastal and tower.  Mounted 3/4″ plywood backer on wall at feedline distribution point.

3/25/09 — Acquired another 2,000 feet of 1/2″ hardline.  Now I can put unbroken runs from the shack to the tower.  I have decided to mount the StackMatches at ground level at the base of the tower.  Also acquired 1,000 feet of 4-18AWG with tape and braid shield to use as control wiring.

3/14/09 — Gave a presentation on Antenna Stacking during the Louisiana Contest Club meeting & forum at the Rayne LA hamfest.  Met John WE3C at LCC meeting.  After discussion, now I’m not sure about mounting stacking relays up the tower.  Decidedly undecided, again.

3/13/09 — Have begun checking inventory of antenna & parts to ensure all will be on hand to assemble and mount on the tower.

3/6/09 — Visited W5WMU where I spent four hours (midnight to 4am, 80m & 160m) operating in the ARRL DX SSB contest.  My wife and I were on the way to New Orleans for a 5-day Carribean cruise.  She even slept at W5WMU!

2/16/09 — Received from JefaTech 2,000 ft LMR400 type and 500 ft LMR400 flex coax.  Have decided to install my 4 StackMatches in an enclosure on the tower just below the middle set of guys, roughly 75 ft up.  This will allow the individual antenna feed lines from the StackMatches to be about 50′ long, instead of 120′.  11 times 70’= a good savings in both money and dB!