Hey Scott - I watched bits of the video. I saw the plan to power the plate TX with 240V !! Jeez…..!
I, like you, enjoyed Jim’s points of issue.
John VK6JX
P.S my YC156 amp is going great guns on 160 and 80m. What a great tube.
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On 12 Mar 2025, at 3:03?am, Amp Guy Llc via groups.io <kb1sel@...> wrote:
?I suspect this project will only end with embarrassment for all parties involved.
I do not watch the videos this person publishes. I watch and read only what I know to be correct, With the intent to learn.
Sad thing is there are so many people that think anything they see online is correct.
I just pray no harm is done to anyone or anyone’s property from this mess.
I only know of it from what Jim has told me.
4 minutes of my life wasted.
On 2025-03-11 12:31, Jim VE7RF via groups.io wrote:
Looked at more of the BBI video. He has done the fil choke wrong.
His method will saturate the type 43 cores. ( no bifilar action).
The reason 2 x wires are passed through the core, or 2 x wires used on
a rod is, that the current flows up one wire, through the cathode,
then back down the other wire. The 2 x magnetic fields cancel each
other out..... resulting in zero ferrite saturation.
Also saw where they modified the oem socket, and removed the screen
bypass caps....which were originally above the chassis. He has made
of curved copper straps, so the former grid finger stock is bonded to
the chassis. Grid fingerstock sits on top of the copper straps.
Screen grid is also bonded to the chassis.
IOW: he's gonna try and run it as a high mu triode, with both the
1750 watt rated screen grid.... and the 500 watt rated control
grid, both bonded to the chassis........ no different than a 4-400 or
4-1000 with both grids bonded to the chassis. Problem is, the
control grid in that config dissipates most of the power, with very
little diss on the screen. That's why the high mu triode version
(3-500Z / 3-1000Z) has double the grid diss...vs the tetrode.
A 3x10/15/20 high mu triode has 500 watts of grid diss. That's
for 15/25/30 kw pep out. And typ 750 / 1250 / 1700 watts pep drive.
Now BBI wants to stuff 20 kw of drive into a tube that only has 500
watts of grid diss....... well good luck with that. It requires a
3-6 kw grid.
Apparently, they are gonna run the B+ supply on 240 vac single
phase. Doable, but will require a 250 kva ccs xfmr out in the
street, pad mounted....and a 1000++ amp rated drop wire.
They are gonna find all this out the hard way.
Links:
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[1] /g/ham-amplifiers/message/41063
[2] /mt/111589618/8135091
[3] /g/ham-amplifiers/post
[4] /g/ham-amplifiers/editsub/8135091
[5] /g/ham-amplifiers/leave/12941173/8135091/773995006/xyzzy
