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January 26, 2010

   Well, obviously I haven't been very good about keeping the site updated.  Maybe I will get better at that after the baby arrives and we can't go out as much... or maybe I'll get worse...

   Guess what?.... The test was wrong.  It's a girl!  Her name is Olivia.  We've got the nursery just about entirely put together, there is just the bouncer and something else I don't remember left to assemble.  Aliesha has a giraffe, a zebra and a tree painted on the wall.  The crib, window shade and other things are all Zanzibar themed.  It looks pretty nice!  We have one class of Lamaze to go and she is due on March 5th.

   Pregnancy has been pretty rough on Aliesha and she has been off of work a while already.  She is going to physical therapy to try to keep as much of her mobility as she can.  I hurt my right shoulder at the gym back in August so I go too.  I think I'm getting better now, she won't really do that until March!

   Meanwhile I haven't gotten very far with the radio projects.  I'm trying to get a nice workshop set up instead. That way I can start a project when I get a chance on the workbench and then I can leave it there and it will be as I left it when I get back.  Currently I either use a TV tray in the livingroom, my shack desk (a mess which also gets used for all sorts of other things) or sometimes just my office floor.  So far I have the garage almost cleaned out.  I've put up pegboard on 2 walls and hung up all sorts of stuff.  I have my workbench designed (half on paper half in my head).  Currently there is a small and very makeshift workbench in the garage which the previous owner built.  It has a cold water faucet underneath.  I would like to rip it out and add a hot water faucet and a drain.  then I can put in a utility tub.

   I did start to work on the SM0VPO SSB transmitter.  I tried to build just the oscillator section of the Exciter on a breadboard.  First I collected the IF can from an old radio I got at a hamswap for just this purpose.  I wanted to test the can to make sure I had the right kind so I built a BFO I read about years ago in a Popular Electronics magazine.  It also used a 455khz IF can and it worked the first try.  I built that first because it was simpler with fewer components.  It was just supposed to be a quick test.

   With the BFO working I thought I was on a roll so I took that apart and tried to build the oscillator from the transmitter design.  I didn't get it to work.  I was trying to use 2n2222s when the design called for BC547s.  I ordered a big bag of BC547s off of EBay and tried that.  Still it didn't work.  I was only trying to build the oscillator to start, not the whole Exciter.  I thought the handwound transformers where not part of the oscillator but now I am thinking maybe I was wrong?  Or maybe this design isn't going to work on a breadboard. SM0VPO does state here that Veroboard and breadboard aren't good for RF.  I assume he means the solder type breadboards but I suppose if those don't work then the solderless ones probably don't either.  Still, it seems like I have seen an awful lot of QRP projects on breadboards on the net and my BFO did work. When I get my workbench built maybe I will be brave and just assemble the whole Exciter dead bug style.

   Meanwhile I went ahead and made a permanent version of the BFO using Veroboard.  I needed a short project to actually build something so I did that the other night while watching a movie with Aliesha in the living room.  I would make a project page about it but it's a copyrighted article and there is no site for me to link to.  I wish someone would buy the rights to Popular Electronics back issues and reprint them!  There wasn't a whole lot of point to me building this as the receiver I put it in doesn't really have the selectivity to make a good Ham receiver but I wanted to build it when I was a kid and failed then.

   The BFO project had a few ideas in it for how to optionally make it adjustable.  I found that was pretty much necessary in my cheap little radio.  The option I went with used a variable resistor and I learned a valuable lesson involving variable resistors and RF circuits.  Don't use ones with metal shafts!  The shaft becomes part of the circuit! Any time I grab the nob to adjust it I change it just by holding it.  If I don't want to have to hold it continuously to listen I found I can adjust it by poking the knob with a plastic pen body.  This is not very convenient.  I found a few plastic shaft resistors online but like I said this radio isn't really good enough anyway, thus I don't want to pay shipping. Maybe I'll pick one up at a hamfest or add it to another order one of these days.

   I did have another successful project.  A couple nights ago I assembled a capacitance meter kit I purchased off of SparkFun. Now I can finally check all those capacitors I picked up in Dayton last year.  Most meters I find that can measure in the PF range are expensive but this one is supposed to do 1pf-500uf for about $14!  I tried it with a couple of 10pf capacitors and it worked great.  It seemed a little off when I measured some 47uf ones but it could be my capacitors are off.  They were higher voltage units, maybe they aren't quite the same with the voltage in my little tester.  I don't know I'll try some others when I get a chance.  It isn't that important I suppose anyway, I have testers for higher values already it's the little ones I have had such a hard time with.

   The directions say to put it in a metal box to accurately test the low values.  I've been looking for a tin which will fit both the PC board and the battery plus leave a spot for banana jacks.  Penguin/Altoid tins fit the PC board but that's about it.  The naked board seemed to work when I tried it so I might just give up and mount it to the bottom of the cardboard box SparkFun sent it in.  It's a nice box and this way I wouldn't need the banana jacks or any leads at all, at least for small capacitors which fit the female header it came with.  Also, if the Sparc goons have their way that SparkFun box might be a collectible!

   Now with a good capacitance meter maybe I can save some money and reuse more parts.  Speaking of reusing parts I like to keep plants in my shack but only have a small window.  I keep a grow light on a timer for that.  I had a little CFL grow light in a desklamp until the other day when it died.  This thing had a huge plastic base and it occurred to me there might be interesting parts in there.  The plastic was brittle from being heated for the last 3 years so I was able to easily crack it open without breaking the tubes.  I found a few interesting inductors, a transformer and a couple of power transistors.  I kept it around to rescue the good stuff later.

   A couple of days after that I was listening to Solder Smoke and heard about Michael Rainey's diode only amplifier.  That brought me to his site and I found this.  A QRP transmitter made almost entirely from the components of an old CFL!  And the parts look just about identical!  I know the two transistors are definitely the same.  I don't trust the electrolytics in mine, they look like a bit overheated but if the rest of it checks out I think I need to build this.  Actually I don't know code yet but that is too convenient, I guess it's a sign I need to learn that too.   Of course, I may change my mind when the baby arrives. We'll see...


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