Monday, July 11, 2016

This Battlestation is Fully Operational

After I left you on the last post I had decided I was going to run a 240v AC line to my shack as well as a secondary 120v, 20A line for my computer and radio stuff.  The idea was to get all this on line before the IARU HF Championship contest over the weekend so I got up early Friday (before my wife got up and complained that the power was off) and got to work.  It took a whole lot longer than I had planned but the finished product is pretty clean and runs the SB-200 really well.  My idle HV now sits at 2500v instead of 2400v and only sags to 2100v instead of 1800v.  

In my last post I mentioned that I had planned to try out those Svetlana tubes I got at Hamcom last year in my SB-200.  I swapped them out before the contest started and they seemed to tune up just fine, providing about 500W out on all bands with 80w of drive.  I ran the whole contest with this setup.

The conditions were not very good until around local grey line when EU started coming in on 40m and 20m.  Up until then, I was working almost exclusively NA stations which is pretty boring for a DX contest!  Operations were pretty tame and according to N5EIL, the Reverse Beacon Network was reporting only 800 some unique calls operating in the contest which is pretty small number.  None-the-less, I really enjoyed operating with the amp and the new antenna and got about 73,000 points from 440 contacts.  I'm really finding this Gap Titan to work really well on 40, filling in several slots for DXCC on the band.  Until now, I've never had a decent 40m antenna.  Even the dipole I had up in Iowa was too short for any effective operation on the band.  

The only thing that bugged me during the contest was the louder-than-ever AC cooling fan in the SB-200.  Sunday I decided I'd look at fixing it.  It's pretty trivial to remove the fan, just remember to shut the power off and let the amp sit for a while to bleed off the HV.  I took the fan out, oiled it a bit and put it back but in all that, I actually made the fan louder.  I needed a better solution.  I ran to Fry's and picked up a few 80mm 12v computer fans and set to wiring them in.  The easiest way to get 12v DC in the amp is to tap off the filament voltage (6.3v AC) and rectify it. (see image below) I used double sided foam tape to stick the fans on the inside of the tube chamber where the old fan sat and ran the wires through the mounting holes for the old fan.  I hooked up the rectifier on the bottom of the chassis and measured about 15v DC on the output.  Looks like I'll be over-volting the fans a bit but I have spares so if they fail, no big deal.  
Read more about the DC fan and other mods at PA0FRI's SB-200 page
Keep in mind, in order to measure all this stuff I've had to move the amp to the operating position, plug it in, and power it on.  There are LETHAL voltages present inside the cabinet.  I had the fans hooked up and they were spinning.  They were very quiet.  I thought, "hmm how much air is moving now?" and made the (nearly) fatal mistake of sticking my hand inside the chassis to feel the air flow.  I must have let my finger hit the filament clip (+2,500V) because in a moment I saw a flash of plasma, the undeniable sound of arcing, and that scent of lightly burnt flesh.  My left arm went numb for about 10 seconds but I walked away from that incident with a few 2nd degree burns on my middle, and index fingers, and my thumb.  BE CAREFUL AROUND HIGH VOLTAGE!!!  

I almost didn't want to share this bit because it's probably the most stupid thing I have ever done but maybe my tale can help keep someone else from making the same mistake.  

After I left things for a couple hours to nurse my hand (and my mind) I went back (with proper precaution) and luckily the amp survived the event.  I put the Centron tubes back in and buttoned everything up, applied power, and was happy to see that the amp had not been destroyed.  The breakers had tripped which probably prevented the whole thing from being far worse.  Even more, I was happy to see that the Centron tubes were working far better than the Svetlana ones, providing 100w more output on all bands, at half the grid current, which meant I could drive the amp with 100w instead of 80w.  Looks like the NIB tubes will go back on the shelf for backup.  I let the amp sit for an hour or so and I was very pleased with the reduced noise - the amp is no louder than my computer fans now - and cooling performance.  With the old fan, the top of the case would be quite warm to the touch, even when idling and now its only a few degrees over ambient. 

The last thing to do before everything is perfect is to figure out how to keep the room cool.  During the contest, my shack got up to 85 F quite a few times while the rest of the house was in 79 F range.  Unfortunately the only thermostat in the house is in the bedroom, on the other end of the house.  Running the furnace fan helps some but I think I need to balance the vents some more to make it really effective.  Just new house things I guess!

Thursday, July 7, 2016

Burning down the house!

I ran by HRO after work yesterday and picked up the 2kw gas tube for my Alpha Delta lightning protection in anticipation of firing up my SB200 for the big IARU contest this weekend.  The little amp has not been powered up since we moved from Iowa and I was a little apprehensive about turning it on again for the first time.  Luckily my fears were unfounded because it fired right up without any issue.

I made a few new pieces of coax to get me QRO handling capability - I was only using RG58 from my radio to the entry panel - and got everything hooked up.  I started tuning the amp on 20m, and watched the power meter go up...up....up....to almost 700w.  I thought, "Oh wow!  This antenna loads up better than my hex beam!"  And then I adjusted the meter for SWR and saw the failure in my ways.  I was getting 5:1 SWR, something had gone wrong!  I grabbed the antenna analyzer and saw my 20 and 40m SWR were both very high, while the other bands seemed OK.  Connectors on the new coax all seemed fine so it must have been the antenna...

So I went out to inspect and it only took a moment to see what had happened. 

This wire was attached to the bottom of the 20m element on the antenna, dangling between the spreaders for the 40m radial loop.  Apparently this little bitty stuff (and its insulation) can't handle a few hundred watts while touching other metal parts!  The insulation had burned off and caused the 20m element to short out to the 40m element.  I'm lucky I didn't burn anything else up!  I replaced the wire with some much, much heavier stuff with nice thick insulation and rotated the loop a bit so it fell evenly between 2 spreaders, maximizing the space between them.  It shouldn't happen again but I'm going to look into a more sturdy solution that doesn't rely on a flexible wire.

With that all fixed up, the amp was showing me 400w out on 20 and 40, just in time for the 0300z CW Ops mini CWT.  I ran most of the time and walked away with 52 contacts, mostly on 40.  I've been really happy with this antenna on 40m.

I still have those 527b tubes I got at Hamcom last year I'd like to throw in and test so I may do a little post on that tonight or tomorrow if I remember.

So I guess the station is primed and ready for the big contest this weekend.  I hope to hear you all on the air!

Saturday, July 2, 2016

The Cove Antenna Installation: Part 2

I left you last time with my entry box installed and the mast for the Gap was installed.  All that was done the week before Field Day and I wasn't too eager to try putting the antenna up myself so I let things sit for a bit until I got back.  (more on FD in another post?)

So the Tuesday after I got back from Field Day, I went out and looked at the mast and the antenna for a bit trying to devise how I'd get the antenna up myself.  My proposed help was still on the way back from FD and wouldn't be back in the area until Thursday and gosh darn, I just can't wait that long!

I was trying to think of a way to lever it up but that wouldn't work, then I got a ladder out and I thought I'd be able to set it in the mount from the ladder but that much leverage at that height was way too disconcerting so I put that idea to bed.  Finally I thought of the best way to do it: lower the bracket to the ground, mount the antenna to the bracket, then slide the whole thing up to the top.  This worked just fine!

Bad picture... 

I got the antenna analyzer out and got pretty lucky, everything was pretty well tuned at first blush.  I ran the coax back to the shack and the matches were not all that great on 40 and 20.  20 was at about 2:1 with a resonant point somewhere up at 14.5 MHz.  40m was OK just not in the CW portion of the band.  The big loop on the bottom (the "TITAN") is supposed to tune 40 but I couldn't get it to make any difference so I just clipped a bit of wire on the end of that loop and that brought the resonant point down to where it was <2:1 on the cw band.

Nevertheless, the antenna is resonant on all bands pretty well now.  The SWR curve on 17 looks really weird so I wonder if there's a loose connection or something but I'm not too worried about it as most of my operation will probably be 20m and lower during the solar minimum.

I let WSPR run on 5w for a day on 20mr and I can't say I'm upset with the results:


So yeah, I'm ON THE AIR in a serious way!  I also jumped in the CWT on Wednesday night and made a handful of contacts including one with France on 40 which is cool because I've never really had an antenna on 40 that was any good for DX, as this one appears to be.  

Hope to hear you all on the air soon!

Sunday, June 19, 2016

The Cove Antenna Installation: Part 1

I started the installation of my antenna at the new house this weekend.  A kind member of the DFW Contest group gave me a GAP Titan DX vertical for the great price of free.  (as payment, I gave away my fiberglass mast kit to another local ham!)  The antenna isn't in the best of shape, at least one of the elements is in serious need of repair and the coax was pretty roached at the connector end.  Oh well, free is free!  

I started out by digging the hole for the mast, and quickly learned what this "Texas soil" was all about. I knew it was full of clay, but I did not expect this!  Basically 4 inches down, the earth turns unto black tar.  The clay is thick, heavy and it sticks to everything.  I spent as much time digging as I did cleaning my tools.  None the less, I got a hole big enough and deep enough to plant the mast in, albeit a little shallower than the instructions call for.  Filled it up with 4 bags of concrete and that's curing at the moment.  The initial idea was to bury a section of pipe that the mast could slide into but I couldn't find anything the appropriate inner diameter so I just said to hell with it and used the mast as is.  This will put the bottom of the antenna at about 6.5'. It'll be interesting to see how difficult it will be to put the antenna on it.  At 25' long and 25 lbs heavy, it can be a bit unwieldy once its vertical.


While that was curing,  I put the antenna together from the pieces I had and luckily everything seemed to go together OK, but it is a pretty simple antenna structurally.  We'll see if I got all the connections right once its on the mast. I'm not sure of a better way to test it beforehand.

Sunday, I decided, would be the day of no return; I would cut a hole in the wall of the house.  I'm sure we've all been there, trying to decide exactly how we'd go about getting coax into our homes.  I decided this time I'd "do it right."  I got a really nice aluminum NEMA enclosure on eBay for a song and I was very surprised to see it when it got in, it was way bigger than expected!  Yes, there were measurements but you don't know what 12" really looks like until you see it in person.

First thing I did was find the studs in the wall beside my operating desk.  I picked a spot in between and slightly higher than where the outlets sit, hoping to miss any wiring.  My stud finder has a wire detection mode and I didn't see any indications so I just dove in head first and cut the 2" hole through the drywall straight away.  Then the radiant barrier.  Then I saw that I was going to have a problem.

If you don't know, many of the homes in Texas are built with brick exteriors.  I don't know about in the past, but these newer homes are actually built with a brick facade. That is to say that there is an air gap between the outside of the structure and the inside of the brick, and the brick merely floats out on its own, cosmetically.  What this means practically, is that the wall from interior to exterior face, is nearly 8 inches thick!  Naturally my 2" masonry hole saw was not going to be long enough, by about the thickness of a brick.  I had to figure out where I was inside and translate that to the outside, so I could drill from there.  It took a bit of trial and error trying to break through from the inside with a very long screw driver until I figured out a way to get pretty close by measuring from my window frame to my hole.  I could see I was drilling into a T intersection in the brick about 27" from the window, so all I had to do was find that area, poke a hole from outside to see and sure enough, I hit it dead on center.


All was not as well as it could have been though.  The hole saw I bought was not really doing much good with my standard rotary drill so I quickly gave up on that idea and went the brute force direction: drill a bunch of small holes and chisel away until you have a hole big enough to fit the 1.5" PVC pipe.  This made quick (and quiet) work of the job and I was through the brick in no time.  I quickly drilled out the holes for the mounting screws for the NEMA box and bam, I was pretty much done with that.  A little expanding foam stuff and some caulk was all I needed to finish up the job.




I'll have to add a little paint to the opening on the inside and you won't even notice the hole probably. I'll also have to fashion a piece of foam that'll plug the hole up nicely.  I'm ready to get back on HF though, I can tell you that!

Friday, June 17, 2016

SOTABEAMS FT-817 digital audio filter

Last night I got around to installing my own LASERBEAM filter into my FT-817 and it works like a champ!  This will be a great addition to the radio, especially now that the stock filters are becoming hard to come by.  In case you missed it, I'll be offering an installation service for these filters, you can see more info about it by clicking the link on the right side of this page. (I also pasted it below for the lazier ones)




The SOTABEAMS LASERBEAM-817 is a digital audio filter that you can place inside an FT-817 that drastically improves the receive audio of this great little radio.  The filter works in SSB and CW modes.  While the installation is not very difficult, it does require opening the radio and working in close proximity to very very small components.  If you find this challenging, that is where I come in!  I have extensive experience building kits of all kinds, especially Steve Webber's MTR.  You can be sure my LASERBEAM-817 installation will be clean and professional. 

The LASERBEAM-817 will work in any FT-817, even if the OEM filters are installed.

Customers who would like to have a LASERBEAM-817 filter fitted in their 817 will need to send me their radio, preferably using an insured shipping carrier (UPS/DHL/Fedex/USPS).  I will install the filter from my stock and return the radio via USPS Priority mail. The price for this service is $110 which includes the filter, installation, and return shipping. 

To arrange installation of your LASERBEAM-817 filter, please email me directly at laserbeam@w0ea.us and I will issue a Paypal invoice. 

Saturday, June 4, 2016

Settling in

We've finally begun to settle into the new QTH.  Every day I unearth something I thought was lost forever to the black hole of the storage unit.  Let me tell you, I am done with this moving stuff!

Last night I got my workbench set up and operational, I even fired up the soldering iron a bit and wired up a cable so I could charge a battery.  Feels good man!

I'm still working on particulars of my operating position and I have not got my ground system set up or hole drilled for cable passthrough or....  There's still a lot of work to be done.

Here's a reminder of what I'm shooting for


And here is where we sit today (pardon the weird stitching - click on the picture for the 3D photosphere)

So things are coming along pretty well and I'm really happy with it so far.  I decided to lower the bench top so I could use one chair and just roll between desks rather than have another chair to clutter the space.  I think this setup will be really ergonomic and comfortable.

I suppose that is about it for now!  Hamcom is next week here in Dallas so I will probably have a post on that as well as look for an upcoming post on my ground installation and cable passthrough and all the other fun stuff on the list!  Thanks for reading and as always, 73 for now.

Thursday, May 19, 2016

KX2 Order form is live!

Here's the KX2 order form: http://www.elecraft.com/elecraft_prod_list.htm#kx2

Things can get a little pricey with all options configured (~$1200)


And here's a shot of the datasheet with the important specs: