First of all I prepared for the CVARC (local ham club) "show-n-tell" and got totally outclassed by Dave Cripe NM0S... well someday I'll get to his "QRP" greatness.. I think I might have took second place there.. but nice thing about CR is that there was at least two other tables of good projects there.
Lets see.. Had "issues" with the 5W class-A RD15HHF driver amplifier. The issues really were the 0.1 uF "SURE" 0.1 uF "50V" (really 16V) 0805 capacitors. Once I got them to smoke .. and replaced them with surplus Kemet mil 100V leaded (chips inside the package tho) caps... well the amp is as designed.
I think probably more cheap Chinese 0.1 uF's are in my future, though (since I ordered a full roll of 4000 of them off of e-bay this week....!) The solution for that is to parallel a bunch of them. Everywhere in the circuit I had three or more worked/survived.. Two or less...*POOF* (NO MORE POOFTERS!). Weird low pass filters got created on the +12V supply to the FET and then smoke "on the bypass.. fire in the cap" when I got fed up and pushed them. Kemets fixed the situation. More than three cheap Chinese caps seem to about = one good American cap. One American cap $ = 5-6 Chinese. Solution: 4 or more Chinese..
New board (post capacitor fire) looks like this:
New Schematic...
Puts out 7W.. 5W somewhat clean at 700 mA Quiescent (yeah this isn't efficient but could be used at 2-3W *without* low passes and is flat from about 1 MHz to 60 MHz) At 5W about +20 dBm is needed clean it drive it. Gain is 18-19.5 dB across all of HF and into 6 meters.
[C8, C9 were the caps that decided they really rather be LED's.. if you were wondering... they were also the source of my mysterious loss of Drain current with drive and all sorts of other nasty things...]
So that's getting there. I might just do two of these in series for the driver for the AN-762. It'd be a bit of a waste of 24W from the power supply but the "Barack Obama" green police are not after me yet. It's simple and clean. At 100mW out or less it's so clean you wouldn't believe it (2nd harmonic is down like -50 dBc at +20 out).
Also got the X-Tronic "fix and concession goodies" in. What can I say.. hot air unit was less than perfect when I got it. Seller probably knew this. But seller gives out good amounts of freebies to compensate, buyer is okay with that.
New standoffs in place in X-Tronic 4000 "Hot air + Soldering". Guess what? They have only a hot air unit now.. I could have saved $50! UGH!
But I did get a good amount of freebies and the soldering iron with that unit is decent. For most the X-Tronic 4000 + soldering iron is recommended.. Freebies follow:
Nozzles.. this time with the correct set of them. Yes the one I was missing prior to this was the "perfect" one for IC SMT rework. But I do have a whole new set. I got a couple of free replacement heaters. I can't say for sure.. but they are "Gordak" (I think from planet "Ork") replacements for .. well Gordak... and ... well.. Aoyue model numbers.. 850A for example is very Aoyue-ish. Not saying the Aoyue and Gordak are the same.. but they might be?
If so the X-tronic is a better deal, no doubt. X-Tronic is "no doubt" made by Gordak.
I got a schematic leaked to me of the X-Tronic 4000 back board. It's completely analog.. no computer controls the heaters.. so it's safer than I thought to leave it plugged in.. but I still wouldn't because all of the DC supplies are always on to the tune of 12-15W AC. Unplug it after cool-down when not in use! The heat gun and iron both use "K" type thermocouples and LM368 Quad Op-Amp comparitor circuits to control the solder heat; the air gun heat and the fan motor on the heat gun. A second loop shorts off the air gun heat TRIAC but keeps the fan on until the secondary loop says otherwise.. factory cal'ed at 55C on my unit.
The display on the front has some sort of "K" thermocouple to deg C multimeter circuit. I should dig on the part number and find the jumper on it that will change it to deg F. $5 says it has one. (Ok.. I'll not bet.. but it probably does.)
Lastly..
I've needed an impedance bridge for "L" at least for awhile. I'm cheap I don't want to spend $100+shipping on the AADE unit. So I won't. Really, I refuse to. I had all of the parts in my junk box, so I was so cheap I didn't even get the PCB board. But it's probably a good thing as my USB sound card (Chinese, of course) for my netbook has R&L channels wired backwards from WB6DHW's board and the original article's Soundblaster Live! card. That took me a few hours to figure out and fix too.
Anyway.. it's good enough that I can wind my Toroids on it and not bother with the HP LCR bridge at work.. but the HP bridge DID calibrate my loads for this bridge! :O)
I'll give WB6DHW credit. The ICL7660D chip for the negative bias off of the USB 5V (regulated to 3.3V and then made -/+ 3.3V for the LM358 Dual Op-amp by the ICL 7660) was rather clever. Especially since I "stock" that part (and ordered more from e-bay since I'm getting "low".) The +/-3.3V is claimed to be safe for the sound card. Since accidentally disconnecting the Rm load puts +2.0V DC on to one of the channels with no ill effects.. I think that putting the ST 78L33 regulator first wasn't a bad idea after all-- instead of having probably +4.5V DC, +2.0V on a screwup is better on the sound card. The circuit overdrives the heck out of the card as it is.. but if you follow the author's instructions that is alleviated pretty well.
The negative voltage generator is needed since the Op-Amp is being used as a one to one High-Z to Low-Z device (a "power follower") and attempting to do the voltage divider for the + input doesn't work well in this configuration. The ICL7660D does though.
The bridge at 4 KHz is good down to about 50 pF.. L seems to be good to about 100 uH or so.. R.. probably several hundred K ish. Not a bad unit.. very accurate too if you pay attention to the proper impedance of what you are measuring and balance the bridge to 10:1 or better for what your are measuring by adjusting Rm.
Verifying level with a scope makes it more accurate as does taking care to balance the bridge out and set the various "tare" points.
Anyway.. fun stuff this week.. plus I worked to exhaustion at work.. But we are getting that much close to the 100% home brew HF.
Oh, yeah.. I ordered off a 320x240 color TFT panel from China to hook to one of the PIC32MX's I sampled and otherwise have floating around (I very well might interface it to the CUI32 I Have that I *bought*). Note: If you want one, buy a UBW32 instead.. I didn't find out about that one until later.. I don't get the purpose of Sparkfun selling both... Ideally I want to take my "PF" 0.5mm sized PIC32MX795F's with CAN/USB and Ethernet, put them on the 0.5mm Proto's I have coming from (e-bay) Thailand (previously I ordered 0.4mm ones only.. because I didn't realize that PIC32MX's come in both sizes.. well... at least the 7XX's do). This, USB hardware a PHY and Ethernet... hooked to the TFT touch screen.. will be the next logical step for the SDR-Cube Software evolution...
I almost bought a STM32 board (to port SDR-Cube to also) for about $15 more and then I realized that I'd need a $80 JTAG to move to that plus another tool set and learning another tool set. I don't like Microchip and their "stealing" GCC for profit (which they'll deny I am sure, but in my humble opinion is so as long as the are selling "optimized" versions).. but the tools are integrated.. cheaper and more available in the West than the ARM stuff is.. so for now I'm going to remain MIPS/PIC32MX but use the TFT LCD 320x200 module off of the ARM kit (which is in the $50 range.. the display was $30 shipped and has support in the Microchip Graphics Lib...).. It should be a cool project. SDR-Cube in living color.
The SDR-Cube port to that will happen eventually. Support Juha and George in the meantime.. it's a good project and they deserve your support.
If my hacked together version works.. then a port to the Mikroelektronkia $175 (shipped) unit is certainly possible as well.. that could be the "new platform".
I'm thinking the BeagleBoard-xm after than.. with the real DSP... Why not?
TTFN..
Hi, you are right, the X-Tronic 4000 is a rebranded Gordak 952 unit. I found a link to them via searching for Gordak on Google images:
ReplyDeletehttp://www.easychinasupply.com/producttrade/last_pt_pro_open/565355.html
Other than some minor cosmetic, front panel changes, its the same unit.
Oh, and another thing I found out... the temp read out is via the 7107 chip which an A/D that can directly drive LED displays. You'd have to recalibrate the temp sensing circuit. So, for whatever mV increase in C you'd have to adjust for F. And, the 7107 just counts it.
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