Saturday, April 30, 2011

40m Double Bazooka build.

I just built another bazooka, this one for 40m.  I used the Carol rg-6 and the same method of build I used before with one exception;  this time I used 1/2" cpvc with caps on it to create a tube to enclose the shorting point.  I drilled a hole just large enough for the mixing tip on the epoxy to fit and "injected" the epoxy into the tube.  So far it seems to be a strong joint on the 40m antenna.  I had it in the air last night and most of this morning with winds gusting to around 20mph.

The bandwidth on this antenna has exceeded my expectations.  I have the entire band below 2:1.  This antenna is actually resonant toward the low end of the band so it is hard to get an accurate 1.5:1 bandwidth, unless you are willing to TX out of the amateur spectrum.  (I am not.)

I believe if I trimmed the ends it would put the entire band below 1.5:1.  This antenna is slated to go to WB8CHE so I left the antenna as is so that he could trim it to his preference. I have been using the antenna to make a few contacts and test it out before mailing it to Russ.  I have went from the bottom of the SSB segment to the top without the use of a tuner and get full output from my Yaesu ft-450AT.

Most of the antenna on the 21' pole.  I have the antenna pretty tight just to make sure it will hold together.
The unpainted conduit body at the feed point.
The epoxy filled tube over the shorting point
(Kind of looks like a caterpillar!)
Close up of the epoxy filled cpvc tube over the shorting point.
My method of attaching a rope to the end.
The complete antenna rolled up and ready to go.

 The ends of the antenna are left raw.  During installation the SWR gets checked and the ends can be trimmed to raise the resonant frequency of the antenna.  This antenna is a bit long so that it is resonant more toward the bottom of the band.  This allows the antenna to be tuned for the particular installation.  (Better to trim than figure out how to add!)  After it is tuned, the ends should be sealed with epoxy, or silicone sealant would also work.

Monday, April 25, 2011

10m Bazooka

I am working on some new ideas for building the bazooka antenna.  This one is built with cheap carol RG-6.  This coax has a single aluminum shield without the waterproofing glue so it is easier to work with than the quad shield stuff.  I purchased a 250' spool at Menard's for $30.

I like the conduit bodies for the center but the weak link is the shorting points on each leg.   I am using epoxy and heat shrink on this antenna and yet I think it may not be enough.  If this joint fails the thought occurred to me to use a piece of PVC pipe over the shorting point and fill it with epoxy.  The down fall of this would be the added cost in materials and more epoxy.

This is the center made from a conduit body with a chassis connector installed and a stainless eye bolt, washers, and nuts for supporting the antenna.  The RG-6 has an aluminum shield so I have used crimp eyelets to make the connections to the coaxial connector.  The eyelet going to the center is soldered in place.

Here I have the body filled with 3 oz of 5 minute epoxy, this strengthens the antenna and adds weather resistance.

Here I have one end of the coax stripped back ready for the shield to be twisted around the center conductor and crimped on.

I used a piece of masking tape to mark where the end of the heat shrink tubing needed to be.

I purchased a smaller tube of epoxy with the mixing tip so I could "inject" epoxy under the heat shrink and around the crimp connector that is creating the shorting point.

This is the above connection after "injecting" the epoxy and shrinking the tubing.

This is the center after the epoxy is set and a coat of paint applied.
I wrap the connector with masking tape to keep the paint off the threads.


I put this antenna up on my 21 foot telephone pole to test it and it has 1.5:1 SWR or lower across the entire band.  The shorting points seem to be solid. (I put plenty of tension on it with the ropes on the ends.)  Although the joints seemed strong enough, I am going to use a sleeve and fill that with epoxy to seal and strengthen the next one I build, most likely for 40m or 20m.

As a side note, the 75m bazooka made with RG-213 is still going strong!

Wednesday, April 20, 2011

Saturday, April 16, 2011

The "New" Station Rig

I haven't got around to posting anything about the new rig.  I replaced the FT-767GX with a Yaesu FT-450AT.

The speaker that looks as if it came with the rig is an old center channel speaker from a Sony surround sound system.  Maybe Yaesu should get with Sony, of course that would make it $100 or more.

As you can see, I use Ham Radio Deluxe to control the rig.  Some of the features are not supported but I did write macros that makes them functional.  The menu settings are better accessed by HRD than via the radio and the dimmer, mic gain, volume, DSP, IF shift, meter selection, squelch, RF power, RF gain, keyer speed, QSK delay, VOX delay, and Vox gain are all able to be set on sliders in the software.  Even the software from Yaesu works well, almost like using the rig directly, but is easier to get at menu settings than via the rig.

I am using a serial to USB converter and both programs work great with it.  I have also played with this rig on echolink and it seems to work well.

This is a compact rig, rather small VFO knob, but the buttons are not to tough to get to.  One thing this rig doesn't have, and I don't know why, is an automatic notch filter.  This could have been put in, after all it already has DSP, so why no auto notch is beyond me.  I have good reports on air with it, although I dislike some features or lack of.  The mic gain control is a funny thing, it has three settings instead of a variable control.  I have to run the mic gain on low for SSB and HI for AM.  I checked into the AM Forum on 3.870 and the AM guys liked the audio once I moved to the HI setting on the mic gain.  This is my first "modern" Yaesu since the FT-767 so I was a bit confused by the "IPO".  This is what Yaesu calls their preamp.  In the off position the input amp is operational and in the ON position the input amp is bypassed.  It seemed a bit backward to me after using other HF rigs in the past.  I just think of it as a preamp bypass and my mind keeps it straight.

The DSP has the usual Yaesu features, contour, manual notch, DNR, and width.  All of these do their job well and rather smooth to.

The display is nice, I like the large frequency display and the subtle blue against black is easy on my eyes.  It has a five step dimmer, from off to bright, and an adjustable contrast, so one can adjust to their taste.  The buttons are black with red lettering.  This was an odd color scheme that doesn't contrast well, I would not like it for mobile use, but with all the memory channels would make use of the buttons almost unnecessary.

Speaking of mobile use, I do think this would make an excellent mobile.  It has many memory channels and keeps about every setting imaginable in the memory, DSP, ATT, IPO, and many more.  It's compact size would fit well in a pickup, but most modern cars would be hard pressed to find room for it.

The built in tuner is quick, quiet, and fast.  I was very pleased the first time I hit the tuner and watched it do it's thing.  It also has a warning beep and prevents TX when a match can not be found.

The rig puts out right at 100w on all bands and absolutely does not get warm.  Just take a look at the fan in the photo's above.  I know, that must be loud!  Nope, you barely even hear it.

All in all, the rig is a good performer, but if you are used to a big rig with a large VFO knob you will find it odd to get used to.