Stupid ART-13 Tricks

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WU2D:
Pump it up,

For the final trick, I have to call your attention to CQ Magazine from June 1965 where there is a great ART-13 article. High Power.

This is a great surplus issue by the way and it includes such classics as the R-19/R-508 for 2 Meter AM, Converting the RT-19/ARC-4 to 2M AM and the Collins ARR-15/R105 autotuning Receiver.

Anyway, the name of the article is High Power with the ART-13. Now most people run the ART-13 at around 200Watts input power with 28 VDC, 450 VDC medium V and 1500 VDC on the HV.

This author, Roger Smith K4PFK, refers the reader to an article in QST October 1963 which converts the ART-13 to SSB - Oh My! The article most importantly shows how to beef up the tank for higher power operation. Autotune still works as normal.

Rogers idea was to automatically switch the HV from 1500 VDC to 2500 VDC when you go from voice to CW and to add a bit of negative bias on the 813. Oh darn. CW ONLY

Anyway 500 Watts input at 75% efficiency or 380 Watts output was the result on 80M. Don't forget the fan, a simple muffin fan blowing out right in back of the PA cage is a standard for the ART-13, whatever the power level.

Mike WU2D

KB2WIG:
 I thought the final mod was to add 10 meters.......  If ur interested, ive got the mod,: I havent tried that yet, as I
 Fried parts of BOTH my 13s' and  am going to have to pull the autotune to get to them (cathode resistors in the hf osc) which I dont want to do without  the famous "crank" to re sync the autotune...
 I run my HV with a 1250v. .25 amp  xfermer and one 23uF 5kv  oil can.   the low voltage uses  a 23uF cap also.... ( See the yeasu stick threat....   no mistakes) so the voltages are up there, but within limits....   as far as the real high v opps, the limiting seems to be the 811s; they dont like reel high volt.....    812s??  theres a thought.....  off the top o the head needs more drive than the 811, but lots of power available to mudulate a higer voltaged 813???    hummmm         klc

Bill, KD0HG:
My solution was to key the ART-13 400 volt supply using a 1600 volt-rated horizontal sweep transistor for a TV set in a series pass configuration to the transmitter. It all fit on a little perf board that I added to the supply.

That kills the multipliers, drive and the screen supply to the 813. 100% silent electronic keying.

You can find the article up in a back issue of ER.

Or, you could just use a relay to key the 400 volt DC supply. Piece of cake. Any relay with contacts rated for 240 VAC will work fine, unless you can work better than 30 WPM...Then we start getting into vacuum relay territory...

Bill

WU2D:
Bill,

High side keying sounds like a winner and it sure is simpler to install than Grid Block. Do you run the VFO 100% of the time during keying? Does it include keying the onboard sidetone circuit? I did a TCS up like that one time but used a 555 for sidetone with a HV transistor keying to cathodes to ground while a relay did the HV on the OSC keeping it on 100% during keying - imagine doing that to an innocent TCS.

What was the ER issue with your transistor mod?

KB2WIG - Yes,I forgot the 10M modification! Classic-  I have not tried that one.

Mike WU2D

rpsmith:
Actually the article was in 73 rather than CQ magazine.  I Know..I wrote it back when I was K4PFK in high school.  As I recall Wayne Green paid me $40 for it, which was actually a fair amount of money back in those days for a high school kid!  BTW..I still have the old rig although it's been stored in the shack attic for many years now.

Roger Smith, AK4RS  (ex-K4PFK)

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