How to repair Heathkit DX-100 Ham Transmitter High Voltage Arching

[@mullioncove1]

Thank you for taking the trouble to make the video : ) My DX100 is OK, but if this happened I would cut out the chassis round the rectifier base to give more clearance. I would not feel happy with the fix shown. God Bless

[@captlarry-3525]

Terry is absolutely correct ! Dust and dirt attract /absorb moisture and together they Conduct Electricty ! Apply 1000 volts and you get arcs. Once a ceramic socket has arced over.. metal deposition occurs . Molten metal is actually in the pores of the ceramic. Either you have to replace the sockets.. or you have to grind away the contaminated layer of porcelein with diamond or carborundum abrasive ( pad or bit). With phenolic sockets a Carbon Path is charred into the plastic. Either way, you have a conductive path which must be mechanically removed ( snip snip) or replace the socket. This is why covering radios with a cloth when not in use is cheap insurance, and why periodic cleaning of the chassis is important. Discharge those caps first with a screwdriver ! BTW this happens with the insulation on High Voltage Relays Too ! Damn hard to find sometimes ! I had a transmitter with half the B+ ( 550 volts dc) on the chassis all the time . Only after I removed a plate relay and turned it upside down.. could I see the carbon path from the relay insulation to ground ...! Nasty. This is why you never want to spill a beer into your running transmitter !

[@scottroberts3801]

Started watching your videos because of amp repair, but I like watching everything because I love learning about all kinds of electrical repair. Thanks for sharing.

[@W4BIN]

I bought my DX-100 used in 1973 and I saw the arc marks on the HV rectifier sockets before I ever plugged it in, so I used two #10 nuts as spacers on each bolt and longer #6 bolts to reassemble, I think I did the same thing for the modulator tubes. There was NO rocking. The 6146 sockets are already recessed, probably for the same reason. (screen Voltage?) I am sure they only arced when lightning hit a power line miles away. My final amplifier oscillated until I soldered down the big shield between the IPA and the final amplifier. Ron W4BIN

[@dhpbear2]

Those sockets look strange. Why those extra contacts? (still too close to the chassis IMHO) I'm surprised Griefkit never noticed this!

[@NebukedNezzer]

I have a lovely dx100b on my operating bench. has fiber washers to space the hv rectifier sockets from chassis. I have installed grid bias regulation so when the modulators are pulling grid current at voice peaks AB2 class. that does not drive up the RF grid bias(grid meter will drop on modulation peaks without that) also when you read the transmitting tube data for 6146b tubes in plate modulation phone service. you are to increase grid drive to 3.5ma/tube or 7ma on the meter(not shown in heath manual). I have a few W3AM phase rotating asymmetry eliminators built from his site info. they really help with strong but not over driven modulation. I use a JT30 mic with the phase rotating asymmetry eliminator in line to the mic input in a box outboard. these are great transmitters. bought mine for 50 bucks with the sideband adapter and had to remove/unmod the for am service. I always get great signal reports on am. I like your work on this transmitter. on 75 meters with 100 watts of carrier at full modulation pep is 385 watts(almost perfect)

[@rciancia]

I am surprised they used bottom mount sockets in there. Drop ins would work much better - but your solution is spot on... perfect as usual - thanks Ron

[@gaylen8467]

Hi Terry, sure miss your guitar amp repair videos. I dont have a Ham, dont use a Ham and never will. Swing back into the light and out of the darkness

[@d-labelectronics]

Soon my friend, just got a hurt amp in the mail. Will be a good one. TD

[@rafaelreyes2589]

Hola que transmisor de eso me recomienda para una estación de radio Broca sister radio station I want to amplifier transmitter AM o FM

[@robertcalkjr.8325]

Nice fix! Thanks Terry.

[@witeshade]

Wow those sockets look incredibly dangerous with such a tiny amount of clearance there. I'm surprised they let that go, even back in the day when safety was a bit less important.

[@VintageTechFan]

I think they designed it with other sockets in mind, then replaced them without realizing the reduced clearance without rechecking.

[@JustinK0RPL]

I think people weren't complete idiots back then. They actually had some common sense.....

[@richarddean1810]

Just a quick guitar item Terry, since you don't play the guitar surely you could capture some guitar level signals sampled into note taker or something you can playback thru the amp, similar to a looping pedal. Then you could have a standard battery of riffs you could demo when you finish a project.

[@johnsimms3957]

What happens if the nylon insulators get hot?

[@d-labelectronics]

Heat rises

[@daviscd3dca261]

Good job mister!!! , Greetings from Chile !!!

[@mikepeine3898]

do you know the value of my 1937 Capehart 112 ? thx ohio

[@Subgunman]

A thouro cleaning around the sockets and a bit of anti corona dope around the HV leads on that tube socket and chassis as well as the nylon spacers. Love the Boat Anker restorations. Nothin beats Hollow State!

[@ChatGPT1111]

Very interesting repair, thanks!

[@tomk1tl]

Another great repair...super job Terry ;-))

[@veerchasm1]

Who else thought they were building Iron Man’s arc reactor?

[@RobertKohut]

Nice!!

[@apollorobb]

73's KC5SRG