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AmpTools/Tech Tips / Re: Heathkit T3 signal tracer
« Last post by goldstache on June 08, 2026, 07:32:31 pm »Thank you so very much for the thoughtful posts!
Here’s where I landed.
So turns out that my shielded cable type mattered.
Went to an RG 70R type, and optical deflection of magic eye was same regardless of AC mains phase input.
Why? Could not say……..
Once the irregularity seemed handled. Wired modern convention
Live/fuse 750ma slow (as I have mains current shunt rig, and won’t be using the heathkit for mains draw)/switch/transformer.
Neut to transformer.
Cap removed, though was good on Sencore.
I did try the no cap first. To see if there was a leakage current. Just to parse what the heck.
Then continued on to the probe discovery.
I’m just using it AF mode. Noise test.
I do have an RF probe, and verified.
I did cap isolate the AF tube from gain pot wiper, had a 10M handy for bias.
And the other oddity has I worked it, was that the unit had a 6x5 present for recto.
In my clamoring for info, noticed heathkit had 2 schemos. Prolly more.
But the other schematic had a 6y5.
And the primarily 12v heated tubes needing the full filament winding, end to end.
The CT was left floating for the 6x5 to one end, to warm.
The 6y5 scheme has that CT at chassis.
Despite having the 6x5 version wired and in place, I decided to 0v that filament CT.
So recto is running
6.3vac - 0v
Instead of the 6.3 -0- ………(6.3v)
Gotta help with some idle noise in unit???
And, all that….
I like it.
It’s really good at finding trash passives (new band name maybe)
Thanks to the both of you. I will carefully read what ya sent a couple times, was just exuberant to share that I got to put to bed…for now.
Here’s where I landed.
So turns out that my shielded cable type mattered.
Went to an RG 70R type, and optical deflection of magic eye was same regardless of AC mains phase input.
Why? Could not say……..
Once the irregularity seemed handled. Wired modern convention
Live/fuse 750ma slow (as I have mains current shunt rig, and won’t be using the heathkit for mains draw)/switch/transformer.
Neut to transformer.
Cap removed, though was good on Sencore.
I did try the no cap first. To see if there was a leakage current. Just to parse what the heck.
Then continued on to the probe discovery.
I’m just using it AF mode. Noise test.
I do have an RF probe, and verified.
I did cap isolate the AF tube from gain pot wiper, had a 10M handy for bias.
And the other oddity has I worked it, was that the unit had a 6x5 present for recto.
In my clamoring for info, noticed heathkit had 2 schemos. Prolly more.
But the other schematic had a 6y5.
And the primarily 12v heated tubes needing the full filament winding, end to end.
The CT was left floating for the 6x5 to one end, to warm.
The 6y5 scheme has that CT at chassis.
Despite having the 6x5 version wired and in place, I decided to 0v that filament CT.
So recto is running
6.3vac - 0v
Instead of the 6.3 -0- ………(6.3v)
Gotta help with some idle noise in unit???
And, all that….
I like it.
It’s really good at finding trash passives (new band name maybe)
Thanks to the both of you. I will carefully read what ya sent a couple times, was just exuberant to share that I got to put to bed…for now.