I forgot how nice solder mask is, and computer generated traces, etc. I did get the AN-762 built in the last two evenings. Not at all tested yet. Tomorrow evening I'll do the bias regulator tests and then all of my stuff will have to be shelved until after next weekend as I have family commitments until then and I'm getting behind on the sleep again.
But except for somehow nicking one of the bias resistors it turned out picture perfect. The nick on the resistor won't effect how it works, either. The Toroidal transformer is very tight where the center screw goes through the 2N5190 and it's difficult to get it all to fit there without scratching something. No biggie.
Note the 2N6488 pass transistor for the bias circuit mounted upside down to make the pin out the same as the obsolete 2N5989 ... the 2N5190 is on the bottom with the screw started through it. The transformer (the toroidal one) is extremely tight there.. so that is why I nicked up the resistor.. probably when cleaning up the solder joint on the top of the one turn wire. Be careful with this.. but you can't get the two transformers and the silver mica in much farther back than I have them so some mechanical slop will be needed here. The 2N5190 needs to face down and thermally connect with the heat sink-- with silicon heat sink grease and be screwed down to the heat sink, so the screw here is unfortunately necessary.
Like I said, a test of the LM723H "tin can" regulator is next. The "build hints" that come printed out with the kit (I have a scan of them if someone needs it.. e-mail me) state that the regulator can be pre-tested under a small load, say a 15 to 100 Ohm resistor 1/4W ... so that's tomorrow night probably.
Two more views... notice how tight the screw on the 2N5190/Toroidal transformer is. I doubt if there is a good way around it. Overall all looks pretty good though...
After testing the bias circuit with the temporary resistor, I need to mount the MRF-454's and adjust quiescent bias as in the app note... Then I have to decide if I want to rig a couple of connectors on it and test the unit into a dummy load. I could hook up the directional coupler and the 141T to it and see if IMD is in line before I build the filter bank too.. Same deal about power out. I'd also like to get 5W or so out of the SDR-Cube to drive this to 100W+ so I need to build my single Class A RD16HHF driver too.. it is a big project making a 100W HF rig from scratch...
I also decided to try and bypass the 0.1 uF capacitors from the sr63ng with 10 uF tantalums to see if that brought up the audio level. It did. Not as much as I thought it would, but the unexpected pleasant side benefit is that the low audio response is remarkably better and it makes SSB and AM (especially SWL) sound even better than it did. It's sounding great now. Even though I probably only gained 6 dB more in the passband totally.. I can tell the response is flatter. I'll leave it that way for now.
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I got started late tonight as it appears that my XM radio subscription (which was last a three year term starting 3/8/2008, had them for 7+ years) was terminated 6 weeks early.. so I spent a couple of unsuccessful hours trying to get my radio reactivated via an online hit until it's up (and I won't renew) 3/8/11.. didn't do it even thought their computer showed it should work and the hits were getting sent... I don't want to call them either, except to cancel... It seems that many of the horror stories about XM under the new "Howard" regime (Sirius) may be true. Damn shame too as five years ago before the merger (thanks for protecting us Uncle Sam!) it was awesome and well worth the money... not now... monopolies suck--especially "entertainment" ones! I suspect that if I call I'll have to re up or I'll remain dead. I'll remain dead.. hopefully they won't try to reconnect and bill me and send it to collections like I'm reading is happening to many people online. What a bunch of thieves....sigh...
'Till Next Time...
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