Ubuntu is probably the easiest to get up and running the first time out, but Mandriva runs a close second (in my experience) in terms of best first impression.

After you get comfortable with Linux, and if you get the itch to go further, OpenSUSE is probably the next step. Very strong in networking, security and about as stable as it gets. All three are available for the time it takes to download the CD(s) or DVD. All three allow dual boot Linux / Winders.

You'll want 512 megs of RAM and 32 megs of VRAM (depending on how graphical you plan to be) and a 20 gig HDD. If the computer is a 500 MHz PII the Gnome desktop is the better choice, for an 800 MHz PIII or better consider KDE for the GUI. Gnome is the more established desktop and has the greater variety of native apps. But, the market is moving toward KDE and there's a new version due on December 11th.

Could be very cool.

For those considering a recycled PII / 350 or 450 for a peek at Linux, 256 megs of RAM and a 4.3 gig drive will get you there with Xubuntu. The interface is kinda' no-frills but that's a good thing on an older machine. The kernel is the same and just as reliable.

BTW: This message comes to you via OpenSUSE 10.3 / KDE / Firefox.

It works.
 

You want a ton of modulation? Check this out: http://hawkins.pair.com/wlw.shtml

About mid page on the right you'll see a pic of one of the twin modulation transformers WLW used when they were running 50 Gallons Plus 10 dB on 700 kHz. Yeah... Half a megawatt.

Rumor has it that at night in downtown Cincinnati whenever they played something with a strong bass line the streetlights would pulsate slightly in time with the beat. Note the outdoor heatsink for the PA cleverly disguised as a pond...

That's what I call serious modulatin'!

Interesting coincidence... I'm currently considering building a Part 15 AM transmitter-ette to tickle some of my BCB boat ankers with some appropriate tunes from http://www.hylit.com

Been scrounging the web for design ideas. Since I have more tube vintage parts in the junkbox than Oz has Munchkins, hollow state is probably the way I'll go.

Check this out: http://groups.msn.com/GospelRadio/cathodemodulationbycunningham.msnw

Dude claims to have whipped cathode modulation into submission and offers * Super Modulation * up to 125% on peaks. I guess I'll have to take that claim on faith...

For the purposes of this thread I think this link offers the better advice: http://www.montagar.com/~patj/cathmod01.htm

Note that cathode modulation was chosen, but not for technical merit or efficiency... The lack of a proper modulation transformer was the deciding factor. Since I'll be working at much lower power levels I'm thinking plate modulation is in my future. If it was good enough for The Orlons back when, it's good enough for me today.

As for screen or grid modulation, Heath did a bunch of that in the 60's and (if I recall) their smaller rigs were not well regarded for audio quality. The DX-100 and Johnson Viking were, and both are plate modulated. Click here

http://bama.edebris.com/manuals/heath/

for a peek at how Heathkit did low level modulation in the DX-35, DX-40 and DX-60. Transformers were expensive parts when bought new. Still are today, but through the miracle of junque...............

*** Correction ***

R101 and R102 are the emitter current balance resistors for the two pass transistors... Not part of the current sense / current limit circuit. Astron got kinda' fancy on this one and you may need to spend some time poking around with a DMM. Review the TI datasheet for the ua723 here: http://www.ortodoxism.ro/datasheets/texasinstruments/ua723.pdf for a circuit description and application examples. Note that pins 2 and 3 are current sense and limit, trace out from there.

If it were mine I'd likely replace the ua723 as a first step. Chances are that's your boy, and be sure to re-check the output voltage before you connect the rig. Astron used fixed value, hand-selected resistors ('Rx') to set the voltage out and they may need to be revised with a new regulator chip.

Need a schematic? http://bama.edebris.com/manuals/astron/

Most xx723 based regulated supplies use a low value series shunt resistor after the pass transistor(s) to sense the current load and shut down the supply when it's overloaded. In the case of the RS-20A, check R101 --- .1 ohm, 10 watt, wire wound. Should be very easy to find. If that resistor goes higher than normal the supply will shut down on a light load.

If the 'big resistor' tests good, replace the regulator chip. GL.

One Other Thot: Since we're talking loop, I don't see a screaming need to limit yourself with a two dimensional concept... If you have some height in the attic, why not use it? Like... Four V's arranged into a rectangle, or maybe a V on the short sides with a W on the long sides.

Do not park a VW in the attic, just keep those two letters in mind the next time you eyeball the space.

I've been thinking about putting a terminated loop in my attic as an SWL item that might throw a signal well enough for domestic contacts on the upper HF bands... Consider a loop with an 800 ohm non-inductive resistor rated at half your expected TX power equidistant from the feed point on the 18' span.

Feed it with a 4:1 dual core Guanella style current balun into a parallel run of RG-59 or RG-62 arranged like shielded twin lead. Tie the shields together at both ends and wire the center conductors like a balanced feed line. Hang another 4:1 current balun at the radio end and see how it plays. The terminating resistor can be a group of surplus 2 watt carbon items wired in series / parallel (depending on what value(s) you can score on the cheap) into something that an Ohm meter sees as 800, +/- 10% or so. Ten 2 watters will dissipate 20 watts (nominal), a little more with an intermittent duty cycle like CW or SSB --- And I wouldn't recommend running more than 40 - 50 watts into * any * indoor antenna.

You want something balanced that's ground independent like a loop, setting up a terminated loop might give you several bands to play with. Also, don't be afraid to test with a 1:1 balun at the radio end. Could give you another band, could suck boulders. If you're home brewing the baluns this won't cost more than a little time and wire. At the power you'll be running you can probably get away with 1" cores and wire salvaged from CAT-5 Ethernet cable scraps. While you're on that thought, you could build the loop from CAT-5 as well with all conductors in parallel. Think of it as Compu-Geek Litz Wire.

18' x 8' isn't much to work with, and there are two schools of thought on this... One is to arrange the loop with the largest possible enclosed area, the other is to get as much wire in the loop as you can. Visualize bow-ties and tortured rectangles.

If all else fails, think "Kinky Fan Dipole" for 10m, 12m, and maybe 15m.

(?)

An ugly antenna makes more Q's than none at all... Right?

All I know is that I used an OCFD for several years and worked the world on 100 watts without much effort. Start with 137' of wire, cut it 45.5' from one end for the feed point, then use a 4:1 dual-core Guanella current balun 'tween there and the coax. In my case the cores were Type 43 material, 1" OD, and wound with six turns of insulated stranded #18 silver teflon wire. RG-8X made the straight vertical drop to the ground (chosen for less weight). From there it was a pair of PL-259's on a barrel connector and RG-213 back to the rig. Waterproof as needed.

I used the SWR meter in the rig to set it up (I know, that's not the textbook way) and pruned only the long end in small increments until it came up mostly flat on all bands. Never needed to use the internal tuner 'cept at the edges of 40m and 75m. It loaded on Six, but a Ringo works mo'better.

This antenna will not work on 160m or 15m, but otherwise it plays like a Wurlitzer... Including 17m and 12m. I don't use 30m or 60m so I can't comment on that, but as an (almost) all band Wonder Wire it was a good deal. No RF in the shack, never tore up a phone or stereo, used to play radio while connected to the web via dialup without a hitch.

The only reason it came down was thanks to a storm and a neighbor's tree that whacked the 30' telescoping TV mast at the south end. Align the wire North-South and it will throw a nice cloverleaf pattern on 20m that's handy into EU, OZ and South Africa. Worked plenty of 'em...

Easiest way to remember Ohm's Law is to visualize an Optician's eye chart with three letters on it... E at the top, then I and R on the second line.

 E
I R

Imagine covering the value you want to solve for with your hand. Cover the E and you see I x R. Cover the I and it's E / R. Cover the R and it's I / E.

If you prefer using V for voltage, remember the box on top of your TV that plays porn...

 V
C R

BTW: The tests have probably changed by now, but ~12 years ago when I went through there were only four or five formulas to memorize that weren't all that complicated. The calculator I used was a no-frills cheapie. Next time you're at a thrift shop, see if you can score a kid's calculator in pink with Hello Kitty above the display.

That should set the proper tone for the session.........
 

Older analogue scopes in the 60 MHz bandwidth range are becoming very reasonably priced and not that had to find, but, even though they're tons of fun to play with... The only two pieces of repair gear that you really need are a hammer and a decent digital multimeter.

Always keep the hammer closer to your operating position than the DMM and let your gear know that if anything has a problem you'll diagnose the issue with the hammer first.

It's the Zen way.

Assuming a coaxial feed with a reasonably decent 1:1 choke balun at the feedpoint to decouple the feedline...

A resonant flat top dipole will have a characteristic feed point impedance of 72 ohms. The 'textbook' SWR will be close to 1.5:1 at the sweet spot. An inverted V with each leg at 45 degrees relative to a real (or imagined) center support will approach 50 ohms at the feed point. A wide V will have a resonant impedance somewhere between 72 and 50 ohms.

While the inverted V might seem to be the better choice thanks to the better match, there is a trade-off to be considered. The flat top dipole has more wire at a greater height with a larger 'area of influence' (for lack of a better term). This may play better in the real world than the relatively minor loss of coupling efficiency compared to the inverted V.

As a rule of thumb, don't let real estate issues stop you from playing radio. Make the best compromise given what you have to work with. Try to keep the feedpoint as high and in the clear as possible since that's where a dipole has the greatest concentration of RF current. If something needs to be bent make it as close to the end points and as symmetrical as possible.

Very few people can a manage a textbook perfect antenna setup, especially for the lower bands. If your inner purist starts to nag that if you can't do it right it's probably not worth doing at all, remind your inner purist that a bad antenna makes more Q's than no antenna at all.

Want to take a walk on the wild side?

Park a 150 watt incandescent lamp at the top of your 35' support fed through a balun to the coax and see how it plays... Surprise! You'll make Q's.

I've heard the WD-40 'secret formula' is primarily kerosene and coconut oil... Apparently unobtanium tends to be seasonal and was dropped from the final spec.

Sometimes the best 'wire' for a permanent installation comes in the form of copper tubing or roof flashing copper... On the back edge of my radio workspace is a 1/2" copper pipe with one end slit with four cuts. That makes it just a bit larger than the 3-0 copper wire that's slipped inside and 'hose clamped' around the slits. Nice, tight compression connection that's greased inside and the 3-0 copper goes through a 1/2" hole in the wall to three 8' ground rods about 10' apart tucked behind the greenie growie stuff out there.

I've had lightning hits that ate phones and TV antennas, but never anything connected to the pipe.

I've used WD-40 on plenty of rotary switches and potentiometers without any problems, but a better bet is Electrical Grade CRC 2-26. Available in the electrical department of any big-box handy guy store. Cleans as well as WD-40 does but lubricates better and lasts longer.

Avoid excessive overspray, wipe off any runs, drips or other signs of excess, and be sure to give the switch plenty of exercise while it's wet. Also won't hurt to Q-Tip off any oxidation that comes loose and is lying on the contact surfaces. The wick action in the cotton works nicely.

There are folks who will tell you to use only contact cleaner. Wrong. The switch also needs a little lubrication and CRC 2-26 is slippery enough to do the trick without turning the switch into a dust magnet. WD-40 can do the same, but it will evaporate completely within a month or two leaving you with a clean switch that doesn't move as smoothly as it should.

BTW: Check the service manual of an old Tektronix 'scope and you'll find similar advice. Don't lube a switch unless it needs it and avoid overspray as best you can. They do mention WD-40 as tested 'safe' on Tek switches.