Tuesday, November 9, 2010

The Antennas

This is the 75m Bazooka on the 25' pole.

This is the 40m Bazooka NVIS @ 7ft. There are 3 wires on the ground that cannot be seen, one directly below the bazooka that is on the PVC pole, and one 6ft on each side of that.  The black rectangle is a horse mat hung up to use as a pitching stop for one of my daughter.

Sunday, September 12, 2010

Amp Supply Company LK-500ZC Rebuild

This project started when I lost a blocking cap on the B+ and it smoked the plate choke.  I have owned the amp for a few years now and knew it had some issues.  The ALO circuit had problems and was bypassed, the fan speed control circuit was not working, and the plate tuning cap had been arced badly and ground down.

With the ALO bypassed I only had plate voltage metering and no current metering at all.  I think the problem with the ALO is a burned resistor that is used as a shunt for the sensing circuit.  This makes tune up a questionable process, but with the forgiving nature of 3-500Z Eimacs I used the amp anyway.  The fan speed was controlled by a light dimmer I installed on the rear to vary the speed of the fan.  I am uncertain of why the original fan speed circuit was bypassed and the switch for high/low was missing.

During dis-assembly I noticed the band switch had the 15m possition burned.  I guess it's a good thing I never used the amp for 15m!

I have removed all components from the chassis and cleaned it. 

I have ordered new blocking caps and installed them along with the new plate choke.

And the new E.F. Johnson Plate tuning cap.
The stem is longer than needed for this amp and I will have to cut it down.

More to come as the project progresses....................................

Sunday, August 15, 2010

Just put the finishing touches on a 75m BAZOOKA!

I used the upper end of the band for the designed area of operating and have a 2:1 SWR from 3.810-3.980

I used Belden 8267 for the coaxial section and the remaining portion of the antenna is made from the 10ga wire that my old dipole was made from.

This is the center support and insulator made from a PVC conduit T. 

I milled the "collar" from the bottom and mounted a SO-239 chassis connector and drilled the top for the eye bolt to hang it from.
After soldering the connections I glued the caps on.  I also put some glue on the outer jacket of the coax to help strengthen the antenna.

With the cover in place I taped the coax and caps together with electrical tape to help strengthen that area of the antenna. (The tape is not shown.)

To connect the wire to the coax, I cut about 3inches longer than needed.  I stripped the outer jacket and folded the braid back over the coax then I stripped the inner insulation off.  Next, I wrapped the inner conductor and wire end together and soldered.  Then I folded the braid back over that joint, twisted it, and soldered it onto the previous joint.

Time will tell if this is a mechanically sound antenna.  I was a bit surprised by the narrower bandwidth. The bazooka I built with RG-6 for 40m covers the entire band, but the entire length of it is RG-6 coax.


I have epoxy potted the center with 5 minute epoxy.  This helps to hold the coax in the conduit body and seals it from the elements.

The bandwidth is narrower than my 40m bazooka, which is to be expected.  It is the same for any antenna, as the frequency lowers the bandwidth gets narrow.  It is somewhat a function of length to diameter ratio.

Friday, August 13, 2010

My Station Rig

Here is the Yaesu Ft-767GX.

This is a good old rig!  I have had a IC-746(original) with the DSP and I have a IC-706MKIIG in the mobile and the 767 is my favorite rig so far.

Wednesday, August 11, 2010

Antenna Issues

I was mowing the other day and caught the guy line holding the outer post of my dipole setup. The antennas started to whip and one of the 160m legs broke at the insulator. I have cut the 160m section from the center insulator and now only have a 75m dipole. I think I will build a 75m bazooka and replace the setup with that.

Wednesday, May 19, 2010

Double Bazooka

I have been looking at trying some different antennae. Field Day is coming up and I am working on some double bazooka antenna builds. This antenna has good bandwidth and is rather simple to build. Some designs claim coverage of the entire voice portion of a band without a tuner.

I have RG-6 to build them from and purchased some PVC conduit T enclosures that have the open panel on one side. I think this will allow me to put the SO-329 connector on them and solder inside the box. I am hoping it will allow me to solder inside and seal the feed point.

I cut down one of the outlets to be flush with the enclosure and mounted the SO-239 on it. I have PVC plugs with holes in them to pass the RG-6 through.

Now the math!

460/f-MHz=overall length of the antenna
325/f-MHz=length of 1/4wave shorted stub in center

What does all that mean? Well, the bazooka can be make in different ways. The one thing that stays constant is the coaxial 1/4 wave stub in the middle. I have seen the ends made of 450 ohm ladder line, 300 line, and good old wire like a dipole. I will be using one continuous piece of RG-6 from one end to the other with the center and outer shield shorted at the 1/4 wave point. Just remember to figure an electrical quarter wave using the velocity factor of the line used. The quarter wave shorted stub is where most of the broad banding of this antenna comes from. The use of balanced lines on the ends may add some broadening by changing the length to diameter ratio. The simple wire would likely not add much if any broadening.

The jacket and shield only are stripped back to allow connection to the feed. The center conductor and shield are shorted at the 1/4 point to create the broadband stub. The center conductor is one piece from one end to the other, do not cut it. The total length is found from the formula previously mentioned.


Saturday, March 13, 2010

On The Air

I have been on the air more and on the computer less, so I haven't posted lately.  I have been active mostly on 75m and 40m.  I did run into a friend on 160m a few nights ago.  I was tuning across the band and heard "Otis", NN2E, and we had a QSO for a few minutes.  I was happy to see the half wave dipole still doing it's thing.

I did do a modification to an old D-104 mic.  I used an MRF 102 JFET to impedance match the element to the FT-767.  I have gotten good reports with it and everyone has said the audio is clean and clear.  I have also wired a Sure Beta Green BG 4.1 electret mic to the rig.  This mic has an internal preamp that operates on a AA battery, so I don't need a bias voltage from the rig.  I have also gotten good reports with it and I like it better than the D-104 because of the convenience of using a mic stand with a boom arm.  This allows me to keep the mic in a location that is good for audio and out of the way of the computer.

I am still debating weather or not to bring the amp to the new operating position.  I will have to run a 220vac circuit to the position and figure out where to put the thing.  Every night on 75m the static is getting closer to the summer time levels so I keep leaning toward putting the amp inline.

It is good to have the radio up and running again.

Sunday, February 28, 2010

IARU Region 2 and Radio Club de Chile Request Amateurs to Keep Emergency Frequencies Clear

“We would appreciate if amateurs would leave free the frequencies used by RECNA, as well as the usual IARU Region 2 frequencies on in 20, 40, and 80 meters.”


Other Frequencies of interest may be:


Tuesday, February 23, 2010

Getting back on the air...finally!

I have the FT-767GX up and running.  At first I only had an NVIS on 40m, but today I got the 75m/160m dipole repaired and some feedline ran to the operating position.  I have half wave dipoles for those bands. 

My brother-in-law, KB9TZU, just upgraded to general and put a bazooka on the air for 75m.  He has a 170kHz 1.5/1 bandwidth.  I think I need to build one or two of these.

Thursday, February 4, 2010

Finally, a rig in the house again!

I finally have an HF rig back in the house.  I purchased an FT-767GX at the Collinsville, IL hamfest.  It seems to be a good rig, I am only on 40m at the moment, but will likely get more bands as the weather gets warmer and I can get out and work on things.  I have been getting very good audio reports and the receiver seems good, very quite.

I am using a NVIS antenna that is 7' above the ground with a reflector at ground level.  The antenna is 66', about a foot long, and flat topped on pvc pipe.  Look me up on MIDCARS at 7.258 LSB.

Thursday, January 28, 2010

Icom 9100 HF/50/144/440

Icom finally working on a rig that has dual receive with HF/50/144/440.  I hope it will have a cross band repeat function as well.  It reminds me of my old IC746.

Rigpix.com - IC9100

This is definetely an option for my next purchase.

Wednesday, January 27, 2010

Calling Area HAM's for Field Day 2010

I am looking for a few HAM's to put together a field day station for the 2010 Field Day.  I am located in Ramsey, IL and would like to have another event at the local state park or one of the parks in the town.

I have helped organize field day operations in the past and have had a wonderful time.  Usually with good food, good friends and hopefully good band conditions.

Anyone interested please leave a comment and it will be forwarded to me.

The event will be June 26 & 27, 2010.

Photos from past events: