Wednesday, June 17, 2015

Field Day 2015

The end of June is on the horizon!  It is almost Field Day time.

My local club is composed of many like minded Field Day maniacs.  We all live and breath field day for most of the year.  Our K3's get up rooted from their normally comfortable shacks to serve as contact machines for the 24 hour period.  Our fleet of Honda generators get fueled for the task.  Everything Ham Radio gets removed from our storage locker and taken to the field.

Our usual configuration includes a Mosely TA33 at the top of a 40 foot Rohn tower that is painstakingly installed and lovingly tied down for the possible stormy weather we sometimes incur.  This year we have decided to go with all wire for simplicity. We have a host of 1/2 wave dipoles at the ready.  We will operate 3A from a local park with a GOTA station on site.We do our best to maximize the extra available points, including invitations to our elected official and served agencies.  We even get the Boy Scouts to come out for a lesson in radio and a possibility of earning a new merit badge.

So come listen for K9OR (3A IL) and WM9Q (GOTA).  We will be happy for the contacts.  For my friends across the water (where ever you are), your contacts count as well so listen out for us.

73 for now,

Sunday, November 16, 2014

Low Band Receiving Loops and the Evolution of the Trapped Inverted L

The chill in the air tells me winter is on the way.  With winter comes low band fun!!!  This winter I am sporting a new Antenna Dinamica (AD - Terminated loop receiving antenna.

I ordered the antenna last winter but only recently got to put it up.  I installed a short pole in the back yard and mounted a Hygain CD45II Rotator on top of it. On top of the rotator, I installed 10 ft pipe (1 1/2" aluminum electrical conduit) and the AD loop.  Remember, this loop is a directional antenna so it needs to be pointed at the transmitting station.  Because it is terminated, it is a broadband antenna so it works great on 160, 80, 60 and 40 meters.

My main low band transmitting antenna is a trapped inverted L.  I made the trap from RG400 coax and PVC pipe.  The trap is tuned to the low end of the 80 meter band.  The antenna sits on a DX Engineering radial plate ( and 20 radials varying in length  from 20 to 125 ft.  The impedance of this antenna works out to being about 17 to 18 ohms so I use a 2:1 impedance transformer to get this up to a respectable 35 ohms or so.  I tune this antenna with a Palstar HF-Auto ( antenna tuner.  The antenna works quite well as a transmitting antenna but can be quite noisy for RX.  So I needed something else, hence the AD loop.

Since the AD loop presents a loss instead of gain, I have installed a DX Engineering preamplifier ( inline at the receiver.  I feed the antenna with RG-6 coax that has negligible loss on 160 and 80 meters.  Therefore, having the preamplifier at the RX instead of the antenna is not a real issue.  The beauty of the DX Engineering preamp is the noise figure, at 3.5dB it is fairly decent. The low coax loss does little to ruin that noise figure. Initial tests of the antenna involved tuning in local AM broadcast stations and rotating the CD45II.  First thing I noticed was I could effectively shut off a station by pointing the antenna away from it.  WOW!!  On the air tests on 80 meters was rewarding as well.  C21GC was on the air, couldn't even hear it above the high noise at my location on the inverted L, the AD loop pulled the signal out of the noise and got me a fine new country on 80 meter CW.

So back to the inverted L....  I have really spent a lot of time with this antenna.  I initially started with only a 130 ft wire and no transformer. When attempting to tune the antenna with the HF-Auto on 160 things were great with 100 watts.  When attempting to tune the antenna on 80 meters the Palstar was really unhappy.  I used a RF Experts AA54 antenna analyzer ( to find an alarmingly high impedance on 80...  So what I learned, 1/2 wave long wires are inherently high impedance beasts and probably not the best antennas to attempt to tune with an auto tuner.  Even worse, when I tired to apply high power (1Kw) to the antenna on 160, the tuner SMOKED!!!  So what else I learned,  17 ohm impedances are tough on even the best of tuners at high power levels.  I started thinking of what was required to get the 160 meter impedance up and the 80 meter impedance down.

Enter the 80 meter trap.

I initially bought a pair of Unadilla ( 80 meter traps.  I did some simulations of the antenna in EZNEC and determined the appropriate spot to install the trap.  So the newly configured wire was hoisted into the air and it was time to test.  The data from the AA54 was quite promising.  The resonance points closely matched my EZNEC simulations and the impedance looked good on 80 meters now ( it was still pretty low impedance on 160).  I tuned the antenna with the Palstar and all was good.  I tuned the amp into the dummy load and then applied 1KW of 80 meter power to the antenna.  Ok not bad, life was good things were happy.  So now its time to try a contact...  I found a station and sent my call,  no answer, tried again, no answer but this time I got an SWR alarm from my LP100 watt meter and the HF-Auto takes off on a tune cycle.  OK what has happened.  I pulled the coax off the back of the Palstar and attached it to the AA54 antenna analyzer.  I ran a 160 meter sweep and saw no problems.  I ran an 80 meter sweep and noticed the SWR was extremely high.  I ran a wider sweep and saw that my resonance dip had moved from roughly 3.55 MHz to some where around 6 MHz.  NOW WHAT!!!

 I waited for the light of the next day and pulled down the inverted L wire to find a large crack in the side of my trap.  I replaced the trap and hoisted the antenna back in the air just hoping I had a bad trap.  On a lark, I disconnected the trap inductor and measure the capacitor with an ohm meter to find it measured 11 ohms!!!  Back to EZNEC, I inserted an 11 ohm resistor where the trap was and re-ran my simulation and matched exactly the results I saw with the antenna analyzer.

So with the antenna back in its original functional state, I made a second attempt at power application.  Long story short, the trap burnt again - almost instantly. I contacted Unadilla about power handling prediction for the trap only to be told that they were not appropriate for the application.  Seems that these traps were designed years ago when output powers were lower and few hams owned amplifiers.  For most applications, these traps are fine... just not mine.

Enter the coaxial trap....  I used a piece of RG400 and 2 3/8" PVC pipe to build the trap.  The design data was calculated using a piece of software called "Coax Trap" written by VE6YP (  The PVC pipe was capped off using pipe caps with eyebolts fastened to the centers.  Stainless steel hardware was used through out.  The trap was tuned to the low end of 80 meters using an MFJ259 with the grid dip coils (MFJ-66) by adjusting
the lay of the coils on the PVC form.   The trap was waterproofed using self sealing rubber tape.  The trap was installed in place of the now broken Unadilla trap and the antenna was hoisted into place.  The new antenna was subjected to repeated applications of 1Kw on 80 meters and has survived.

Still we have an issue with 160M.  I want to run higher power into the antenna on 160 with out blowing up the tuner.  So I ordered a balun designs ( 25 to 50 ohm unun.  I installed the transformer and all is now fine up to 500 watts.  Not sure if I want to attempt any more power and possibly damage my tuner again.  I may later just replace the auto tuner with a manual one that will be more forgiving of my mistakes.

So why so much power.  Inverted L's are great antennas but are hopelessly inefficient due to the low radiation resistance without a very extensive ground system.  I estimate that I am burning roughly 1/2 to 2/3's of my power heating my ground system.  I already have about 2000 feet of wire in the ground system and my XYL is not amenable to me copper plating our yard.  So sadly I am dealing with the effficiency problem by burning more power.  All in the pusuit of a good country count on 160 from a residential lot.

Until next time


Sunday, September 21, 2014

Titan DX followup and the AV640

It has been quite a while since I have updated this blog.  I wanted to update the state of affairs for the Titan for those that have been following.  I would also like to talk a bit about the Hygain AV640.  This winter was extremely hard on all of my equipment.

The Titan met its unfortunate demise one day this past winter.  We had some cold temperatures and high winds (57 to 60MPH gusts) that just were to much for this great antenna.  I went outside one morning to find this fine antenna bent into a shape that can best be describe as "banana".   I pulled the antenna down and laid it on my roof until temperatures were more positive... literally. 

I really liked the Titan.  It is an awesome concept being a vertical dipole.  I never could get the models to even come close to predicting anything that resembled the real antenna performance.   You really can go wrong with this antenna as long as you can keep it out of high winds.

So what did I replace my Titan with... a Hygain AV640 Patriot of course!!  While not a vertical dipole, this antenna is another great design.  I have several friends in the area that have these verticals.  A couple of these guys have extremely high DXCC country counts with the little gems so I was enticed.

This antenna is several parallel 3/8 wave full length/loaded (depending on the band) verticals with 7 80" counterpoise radials.  It has a matching transformer at the base that improves the match to a 50 ohm coax.  The wind survival spec is better than that listed for the Gap but we will see how well it survives this coming winter

Assembly of the antenna takes time and patience.  Typical of all things Starksville, there will likely be missing and/or wrong parts that will need to be replaced/remade/invented.  Go through the parts list and inspect carefully before you get started with assembly.  Never assume that factory tightened/assembled parts were done correctly... double check everything.  Once you get this gem put together, you will be pleased with the performance.

W9DXCC was this weekend here in the Schaumburg.  Two days of mingling with budding and expert DXers was fun and educational.  All the talk of dxpeditions and massive pileups put me in the mood to go and find some remote island to visit for a week or so.

Well off to go warm the amplifier up...

until next time,


Monday, May 20, 2013

Titan Dx part 3 - the final part

he Titan is in the air.  My intent was to mount the antenna to a currently installed chimney mount.  Unfortunately, the chimney mount was in a state of disrepair from several years of weather exposure.  The antenna was placed on a 15 foot pole which placed the base of the antenna about 4 feet above the roof line.  A guy kit was secured from gap and a set of 3 guys were installed.  The wind survival of the antenna appears to be pretty good but time will tell.  The antenna is extremely top heavy so I would certainly recommend a guy kit for all but the most shielded of installations.

For my antenna, I did not utilize the 40/10 meter "hoop".  Instead, I fashioned 2 wires of length equal to what would have made up the 10 and 40 meter portions of the hoop.  The SWR on all bands but 30M is respectable.  I still have some experimentation to do to improve the 30M SWR.  I have not tried this antenna beyond SWR testing on 80 meters.  On 80 I have this antenna tuned for the extreme low end of the band  and I get good VSWR on the lower 50KHz of the band.  It was a bit lower than I wanted but I can live with it.

I spoke with the Gap folks this past weekend in Dayton.  They suggested that I increase the amount of overlap between the longest lower tuning rod and the rod that it is connected to.  This is supposedly the portion that resonates both the 20 and 30 meter sections.  I will see what I can do.  It is not a priority as this antenna is intended to be a multiplier antenna in an SO2R contest setup and 30 m is not going to be used.

First impressions of the antenna are positive.  I have made various contacts on 10 through 40 using the antenna both state side and DX.   How does it compare to a Steppir.....  not even in the same league!!!  Compared to my dipole, the antenna hears about as well for the most part.  I will continue to experiment and may report back in future blogs.

OK back to the modeling.  As I pointed out earlier, I spoke with the folks from Gap with respect to modeling as well.  They attempted to simulate the antenna with Eznec as well and were equally in successful.  It was explained that the close spaced rods just make this antenna impossible to simulate even with NEC4.  As it stands, I will end my attempts as it seems futile.  I will enjoy the antenna as it is.

Until next time,

Thursday, February 21, 2013

Titan DX part 2

I have been toiling over the models for the Titan for some time now.  I promised some results here but I am not willing to release what I have learned until I am sure of the accuracy.  Currently the models show some real promise but are not yet verified.  I am still unable to simulate the 80 meter operation of this antenna which disappoints me a great deal. 

The primary problem in modeling this antenna is the feed method.  The coaxial cable supplied by Gap runs the length of the antenna but the shield is split at the "gap" to provide the feed.  The 80 meter tuning capacitor is connected between the center conductor and shield at the very top of the antenna. The center conductor then ties to the very top of the antenna.  I have been using the capacitance of the coaxial cable in series with the feed point to complete the feed connection.  At this point, I see a number of VSWR nulls at approximately the correct frequencies (within 1 to 2 MHz) but no null for the 80 meter band.   I am still working on the models to improve the results. 

The 3D antenna patterns at the VSWR nulls are not bad at the higher frequencies.  The gains are roughly 2.6dBi for 10, 12,and 15 meters in the models current state.  The remaining bands display either 0 or negative gains at this point and that is the reason for the questioning the accuracy of the model. 

I will continue to explore and hopefully report results very soon.

Until next time

Thursday, January 17, 2013

Titan DX

So I purchased a used Gap Titan DX off of EBAY.  The previous owner was located about 2 hours south of me so I was able to pick the antenna up from his home and bring it back to my QTH.  The 80 Meter portion was tuned for 3.8MHz but a quick call to GAP Antennas put a new capacitor in the mail that should put me down closer to the 3.55MHz that I would like to center on for CW and RTTY.  Of course I have a 3 element STEPPIR on a 50 foot tower so this will be my second antenna setup.  My XYL is THRILLED!!!! ;-)  After I put up the elevated guy system, she said no more towers in the yard.  THIS IS NOT A TOWER!!! ;-)

The documentation with the antenna is fairly detailed with out a lot of drawings.  It seems fairly easy to put together but then again I am fortunate in the fact that this antenna has been put up before and has some of the more complex sections already put together. I suppose I may be singing a different tune once I actually put the pieces together.  I expect to get my exercise when it comes to tuning the antenna for 40 meters.  If you are not familiar with the Titan DX, the counterpoise loop tunes 40 meters.

I placed an order for  a guy kit from Gap Antenna, a coax ground assembly with bulkhead from DX Engineering and some LMR600UF (my go to station coax) and Polyphaser from Antenna Farm.  I plan on mounting the antenna on a chimney mount that is already in place.  The guy kit was purchased because GAP recommends not putting the antenna on a chimney mount with out one!!

The Titan DX is actually a vertical dipole and as such needs no radials to function.  I modeled the antenna in EZNEC and if the results were accurate,  the antenna is not exactly omni-directional on all bands.  Gain wise, the antenna is probably a pretty good performer on 20 and 40 meters but 10 and 15 meters may not be all that great.  On the air time will tell.  Again these results are based on an attempted tape measure derived duplication of the antenna in EZNEC.  I was unable to get the 80 meter cap incorporated into the model so that may also be skewing the results.  I will be enhancing the model as I learn more about EZNEC so I will probably write up some more quantitative results as I improve the model.

I am currently waiting on the delivery of the coax and a warm day to put this thing up so once again I am at the mercy of Illinois weather.

Thanks for reading my first post for 2013.  Comments are always welcome.

Until next time

Saturday, December 8, 2012

160Meter and 10Meter RTTY Contests and Band Cops

Yup I ran them both!

I spent Friday and Saturday night running the 160M contest.  I ran low power with my umbrella vertical.  As compared to last year with about the same amount of effort, I was able to complete about 50% more QSO's in about 13 hours operating time total.  Quite an accomplishment for me at 346 total.  I had added another 8 radials to my radial field so I am up to 18 now and about 2000' of copper on the ground.  The efficiency of the antenna has improved for sure.  I am pretty pleased at the performance. 

Unfortunately, I am not happy with my receiving loop.  Not the antenna itself but the placement of the antenna.  Right now it is in my back yard about 3 feet above the ground.  It allows me to hear well but not well enough.  I am able to hear local stations work DX that I can barely hear above the noise floor.  The Flex 5K hears very well on other bands so I am pretty sure my loop needs some elevation to function better.  I could switch over to the umbrella for receive but the noise is horrendous with that vertical in my suburban location.  Even during the contest, I felt that I was being heard better than I could hear.  So back to the testing grounds with the loop.

Sunday morning was spent on the 10 Meter RTTY contest.  Quite a contest, but with the conditions it felt like I was operating in the contest that no one bothered to participate in!!  The morning started with a YL from ZS land  that I monitored rag chewing with someone from W5 land.  The band was open to South Africa to be sure.  Shortly there after, stations started popping up here and there in the RTTY section of the band.  There was quite a few DX stations on the air and they were fairly easy to work.  Several state side stations as well.  The contest was fun, any time I am pounding on the RTTY keyboard I am having fun!!  Maybe next year the conditions will be better. 

What the heck is with people?  Why do they insist on jumping on the DXpedition transmit frequency just to agitate people?  Sending UP UP UP and LID and ASS to the poor sole that forget to set his split the first time he transmits is not helpful to any one.  PT0S was an atrocious display of behavior both on the internet and on the air by the self appointed Band Cops.  The same old game of on the air jamming and the internet cluster comments were the worst I have ever  seen.  These people should be ashamed of themselves.  The guys from PT0S did a fantastic job with the circumstances they were dealt.  Get over it band cop and please go away.

Until next time