Your scariest kluge

Discussion in 'Radio Circuits, Repair & Performance' started by KL7AJ, Jan 5, 2016.

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  1. W2VW

    W2VW XML Subscriber QRZ Page

    1995 nice, well built 4-1000 RF deck (bought it that way) married to a homebrew pair of 4-1000 modulators cathode driven with audio using a Precision Power PPI-300 audio power amp.

    The modulator tube sockets were fastened to angle stock garage door frame material within a 6 foot equipment rack. No covers. Almost killed the cat. Had those cheesy steel flush mount sockets used on Diathermy machines.

    Power supply was a pair of late BC-610 oil filled transformers in parallel with full wave bridge rectifier/swinging choke input. They could take it without hi-pot failure. B+ 5500 volts under load.

    Modulation transformer was surplus from a Raytheon RA-5. 1300 lbs. Used a pile of Wilcox military surplus chokes for modulation reactor. Over 200 uh in total. Got those and tons of other great heavy stuff cleaning out the basement of Atkinson and Smith in Eatontown NJ when Smitty finally pulled the plug.

    Used foot switch to switch TR and high voltage because a kindly old timer suggested that was safer than leaving B+ on and pinching tubes off.

    Never did get that working 100% but I sure could now. Made plenty of AM QSOs with it. Finally went to 833s and half the B+ because I kept running into mobiles. I desperately wanted to use that beast of a modulation transformer as it had a 1:1 ratio.

    Took it apart a year later and moved on to modifying rice boxes for AM and linear amplifiers.

    1993 Second craziest kludge here was 1948 BC-610F retrofitted to 3-500Z final and modulated with a Crest 4001 solid state audio power amp using half of a T-368 power transformer as a modulation xfmr. Had same 200 uh of Wilcox inductors for shunt fed B+ and waaaay too much Heising capacitance.
    Made one contact, pulled it apart and moved 33 miles away.

    Still using large audio power amplifiers for modulators today on my Johnson 500. Learned a lot from those old experiments.
  2. KE4OH

    KE4OH Ham Member QRZ Page

    Ha! I have you all beat for working kludge gear on the air ... I use a Heathkit HR-10B receiver for CW QSOs.

    Okay, so my kludge isn't really dangerous like some of the other stuff. I'll have to say that my favorite is loading up the Viking chassis to be a 10m antenna!! Still laughing about that one.

    73 de Steve KE4OH
  3. KA9UCN

    KA9UCN Ham Member QRZ Page

    Year’s hack I had a corner dedicated to playing with HF transmitting tubes.

    6KV. DC 3.? KVA. CCS capacitive filtered power supply built on a plywood base with casters and 2 1000 vdc supplies capacitive filtered for screen and grid. Built from old color tv transformers all on variacs. I used solid conductor spark plug wire as hook up wire. All open to the air. It made for great fun when bread boarding an amplifier. Back then I was r-um adventuresome. I made a lot of tubes produce RF, had fun and survived. With that set up and a large tube or two. The moto was. It aint good until you can feel the ants crawling on your face.

    I know with some of my past post some wonder. What is wrong with this guy? Now you know the rest of the story.

    Joe KA9UCN
  4. VK6ZGO

    VK6ZGO Ham Member QRZ Page

    Done something very similar to both:-

    In VK6,there were two "Regional Shortwave" services,due to the lack of local MW stations in remote places in the old days.

    The "powers that be" decided to set up a "Radio Australia" transmission to South Africa after VLW/VLX closed down at midnight,using a spare Rhombic pointing in the right direction.
    As it was an "experimental" service,at the switching hut the feeder was diverted to the Rhombic using a "Frankenstein " style knife switch.

    The routine was to call out loudly "I am going to the hut to switch to the RA aerial!"
    One night,I did this,went to the switch hut,grasped the handle of the switch,opened it and drew two beautiful
    blue arcs!
    Needless to say,I returned that switch to its original position extremely fast!
    Someone had missed my call,& decided to do some after hours testing!

    The handle was removed after that,& we used a long stick with a hook on the end to operate the switch.

    The next one is quite some years later:
    Midwinter in Southern VK6 can get a trifle cool----Yeah I know,VEs would be running around in short sleeved shirts!
    Nevertheless,it was cold enough to feel like you had been slapped in the face
    We got to the Tx site,only to find we had left the "fan heater" behind.
    After shivering for a while,we got the idea of running the standby Tx into the Test Load,& soon were snug & warm.
    I felt a bit guilty about that,but rationalised it because we "needed to warm the standby up to operating temperature" before swapping Txs & testing that one to air.
  5. WB5WSV

    WB5WSV Ham Member QRZ Page

    APR-4 Tuning unit, 70-200 MHZ range, with its 30 MHZ IF output going into a Northrop Ventura UHF command receiver with the audio output from the command receiver into the mike input of my stereo system. Since LV DC was required for the command receiver and APR-4 filament and motor drive and HV DC was required for the APR-4 B+, I had all of this spread around the floor of my living room with cobbled together power supplies, the connections of which would break and cause sparks to fly. A young lady walking by looked in through the glass doors of my apartment and smiled.

    This Herculean effort produced the world's worst FM broadcast radio receiver, one capable of receiving multiple stations at the same time.

    I later repeated this experiment using the 26 MHZ IF of an ARR-52 receiver. I managed to get the NOAA weather station.

  6. K6GB

    K6GB XML Subscriber QRZ Page

    I would guess the Tesla coil my cousin and I built was sort of on the air. Fed the primary with 14,500 AC from a neon transformer. Lit up fluorescent tubes at 200 feet, tore up every radio and TV in the neighborhood.
    9A5DLZ likes this.
  7. K3UJ

    K3UJ Ham Member QRZ Page

    I was the "tester" in a custom transformer shop. IE, Hi-potted the insulation, powered the unit up, measured loss, checked output voltages. This was all good sized stuff, up to 100 KVA. One standard item was a little oil filled 10 KVA, 120 in 20 KV out.

    One day the engineer wanted to see how well built they were. Really stress out the insulation. Asked me do a double induced voltage run, meaning run the primary at double the voltage. Now a transformer core will go into saturation not much above its designed primary voltage. The way around this is use a higher frequency.

    We had an MG setup, 240V 10HP motor driving an alternator putting out 400HZ, used this all the time on power distribution transformers. No problem. Hooked it up, used a variac to crank in power to the motor, reading the test units primary feed voltage. Got it up to about 180 or so, then. FLASH Everybody forgot the terminal insulator on our little unit was only rated to maybe 22KV, now we are someplace north of 30. Nice fat arc to ground. Hit the safety switch, kill power to the motor. Oops, there's no contactor on the alternator output, and it's a self activated field. Had to wait for it to spin down. Didn't take that long, but time did stretch.
  8. W8SPL

    W8SPL Ham Member QRZ Page

    In 3rd grade back in the 80's, I made an AM "Spark Gap" transmitter for a school science project... Sounds harmless enough, but it was powered DIRECTLY off the mains w/ a big ballast resistor to limit current to the 12VDC automotive relay I was using as the spark gap; no filters either so I imagine it was quite broadband as arcing tends to be... I'm sure all the hams around me were quite annoyed when I'd practice code after dinner! Never did get anyone to reply back on the AM broadcast band I was listening on :D

    Also found out that the electrical grid is polarized w/ that contraption because I was using an uninsulated strip of tin can & a nail head as the key... Glad I'm not dead from some of the really stupid stuff I played around w/ before I knew better!
    Last edited: Apr 3, 2016
  9. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Shoulda used a 24VDC relay. They work incredibly well at 120VAC.

    Used to do that all the time in emergency situations at work.
  10. G3YRO

    G3YRO Ham Member QRZ Page

    Although our Mains power distribution is all underground here in England, the telephone wires are still mainly in the air, coming from 30ft high wooden poles. (All the new ones are now put underground)

    When I was at University 40 years ago (250 miles from home) there was an unused phone cable from a pole about 100 feet away going to the upstairs of the house I shared . . . so I loaded that up to get me on 160m and 80m !

    And when I first started working up here in the North about 20 years ago, I hadn't sold my house down south. All I had was my little homebrew 160m SSB transceiver in the car and a mobile whip.

    But one day I put up a temporary vertical . . . there are several bridges over the river in Newcastle (some look like those I see in New York in the movies). So I walked part way across the bridge, and dropped 130 ft of wire, then drove down to the car park below, and hooked this quarter wave vertical up to my 160m rig ! (I also hooked up an earth wire to the metal railing that ran along the riverbank.)

    Roger G3YRO
    KC3BZJ likes this.

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