Re: Total insanity....500KW 11m amp being built.
If they grid drive it...... that tube has a whopping 370 pf of input C.?
|
Re: Total insanity....500KW 11m amp being built.
They don’t calculate , they use the trial and error method.
They think it’s normal to loose a doorknob cap, vacuum variable capacitor, tube etc. Swap part with the next size up and repeat.
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Show quoted text
On 2025-03-12 10:28, HaL Mandel via groups.io wrote: When bolting-up the tube sockets for the GU-84b's
I could tell they were some doozies.
Cleaning the silver metal without removing
it from plated instead of solid metal contact
areas required a toothbrush and a pile or two
of Kool-Amp silver plating powder to get the
'low hanging fruit' acceptable.
The big surprise for me were these green glazed
oblong-shaped capacitors with silver metal flat
contacts on each end. They formed a circle around
one of the concentric parts of the sockets.
The grid port, going back through the neutralizing Breuhne bridge
is bypassed, or perhaps better named as "loaded" with a non-inductive
450 ohm, 50 watt 1% resistor that can easily be replaced
or removed as the neutralizing process is analyzed on the bench.
With the cost of all these little specialized pieces taking longer to
agree with myself that the purchase will probably be useful has
gauged my efforts in getting this project 'hot' and making satellite
contacts on 10m.
This is why, looking at the 500MW nuclear reactor experiment
elsewhere, I wonder who performed the calculations for each
and every component, and how did the design choice fare on
a peer review for viability, feasibility and reasonability?
Hal
W4HBM
Links:
------
[1] /g/ham-amplifiers/message/41070
[2] /mt/111589618/8135091
[3] /g/ham-amplifiers/post
[4] /g/ham-amplifiers/editsub/8135091
[5] /g/ham-amplifiers/leave/12941173/8135091/773995006/xyzzy
|
Re: Total insanity....500KW 11m amp being built.
When bolting-up the tube sockets for the GU-84b’s
I could tell they were some doozies.
?
Cleaning the silver metal without removing
it from plated instead of solid metal contact
areas required a toothbrush and a pile or two
of Kool-Amp silver plating powder to get the
‘low hanging fruit’ acceptable.
?
The big surprise for me were these green glazed
oblong-shaped capacitors with silver metal flat
contacts on each end. They formed a circle around
one of the concentric parts of the sockets.
?
?
The grid port, going back through the neutralizing Breuhne bridge
is bypassed, or perhaps better named as “loaded” with a non-inductive
450 ohm, 50 watt 1% resistor that can easily be replaced
or removed as the neutralizing process is analyzed on the bench.
?
With the cost of all these little specialized pieces taking longer to
agree with myself that the purchase will probably be useful has
gauged my efforts in getting this project ‘hot’ and making satellite
contacts on 10m.
?
This is why, looking at the 500MW nuclear reactor experiment
elsewhere, I wonder who performed the calculations for each
and every component, and how did the design choice fare on
a peer review for viability, feasibility and reasonability?
?
Hal
W4HBM
?
|
Re: Total insanity....500KW 11m amp being built.
It appears they have already? been notified that their proposed? cathode driven config...with both screen and grid bonded to the chassis? is fubar, and the poor control grid will vaporize....with 20 kw pep of drive into the 500 watt rated grid.? ?It wouldn't work anyway, their fil choke is a total write off.?
Dunno where? BBI? got this idea that he needed a 4CX-15,000? as a 1400 vdc? screen regulator.? ?A simple? FWB +? resonant choke, and bleeder would easily suffice...and have superb regulation.?
Dunno if they will take the kind advice of some fellow? 11m? builders who explained? this all? to? De Luna + BBI.? ?The other builders have succesfully built grid driven 4CX-5000 amps, complete with screen and bias supplies, then terminated the grid with a grid loading resistor.? ?So far, they have not responded.?
If they do, they? will have to rebuild the $4K? socket...and replace all the screen bypass caps? and unground both the screen and control grid.?
If they don't take the sage advice,? they can kiss the control grid goodbye.?
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Re: Total insanity....500KW 11m amp being built.
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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Show quoted text
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:
------
[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
|
Re: Total insanity....500KW 11m amp being built.
I think Luke and John will get it working before
SpaceX arrives on Mars, both projects have the
potential to make a big BOOM!
?
Here's a theoretical design using a 4CX3000A as a driver:
?
?
Redesigned 100KW PEP 11M AM/SSB Amplifier
1. Block Diagram
-
Exciter: Yaesu FT-101E transceiver (27 MHz, 11-meter band).
-
Intermediate Amplifier: 4CX3000A tetrode amplifying the FT-101E output to drive the 4CW-100,000E.
-
Final Amplifier: 4CW-100,000E tetrode delivering high-power output.
-
Power Supply: High-voltage supplies for both tubes, plus filament and bias.
-
Output Network: Matches the 4CW-100,000E output to a 50-ohm antenna.
-
Cooling: Forced air for the 4CX3000A, water cooling for the 4CW-100,000E.
2. Operating Modes
Component Details
Exciter: Yaesu FT-101E
-
Output Power:
-
Frequency: 27 MHz (11-meter band; assumes modification or original CB capability).
-
Output Impedance: 50 ohms.
-
Modulation: Built-in AM/SSB modulator.
Intermediate Stage: 4CX3000A
The 4CX3000A is a forced-air-cooled tetrode with substantial power capacity, often used in broadcast and industrial applications.
-
Maximum Plate Dissipation: 3,000 W.
-
Plate Voltage: 4–6 kV (typical operating range).
-
Output Power:
-
AM: ~2,000–2,500 W carrier, ~8,000–10,000 W PEP (Class B, 60-70% efficiency).
-
SSB: ~3,000–4,000 W PEP (Class AB1, linear mode).
-
Gain: ~13-15 dB (20-30x power gain).
-
Input Power Required:
-
For 2,000 W output: ~80-100 W (matches FT-101E AM/SSB output).
-
For 3,000–4,000 W PEP: ~120-200 W (slightly above FT-101E SSB output; assumes slight overdrive or additional preamp).
-
Cooling: Forced air (~200-300 CFM, per Eimac specs).
-
Matching: Pi-network to transition from 50 ohms (FT-101E) to the 4CW-100,000E grid impedance.
Design Notes:
-
Operate in Class B for AM efficiency or Class AB1 for SSB linearity.
-
Plate voltage: 5 kV, ~600-800 mA plate current.
-
Screen voltage: 500-700 V.
Final Amplifier: 4CW-100,000E
-
Plate Voltage: 15 kV (conservative, below 20 kV max).
-
Plate Dissipation: 100 kW max (targeting 50-70% of capacity for reliability).
-
Gain: ~15-20 dB (30-100x power gain, depending on conditions).
-
Input Power Required:
-
Cooling: Water-cooled, 20-30 GPM.
Modulation:
Power Supply:
Output Network:
-
Pi-network or tank circuit to match the 4CW-100,000E’s high-impedance output to a 50-ohm antenna.
-
Components: High-voltage capacitors (500 pF, 20 kV) and inductors (~1-2 ?H).
Power Output Forecast
Assumptions:
-
Efficiency:
-
4CX3000A: 60% (Class B, AM), 50% (Class AB1, SSB).
-
4CW-100,000E: 70% (Class C, AM carrier), 60% (Class AB, SSB).
-
Gain:
-
4CX3000A: 14 dB (25x, midpoint of 13-15 dB range).
-
4CW-100,000E: 17 dB (50x, midpoint of 15-20 dB range).
-
Modulation: AM uses plate modulation on the final stage; SSB is linear amplification.
AM Mode:
AM Output:
SSB Mode:
SSB Output:
Final Specifications
-
Frequency: 27 MHz (11-meter band).
-
Power Output:
-
AM: 70 kW RMS (carrier), 280 kW PEP.
-
SSB: 25 kW RMS (average), 100 kW PEP.
-
Exciter: Yaesu FT-101E (50 W AM carrier, 100 W SSB PEP).
-
Intermediate Stage: 4CX3000A (~2,000 W AM carrier, 3,000 W SSB PEP).
-
Final Stage: 4CW-100,000E (70 kW AM carrier, 100 kW SSB PEP).
-
Cooling: Forced air (4CX3000A, 200-300 CFM), water (4CW-100,000E, 20-30 GPM).
-
Power Supply: Multi-voltage (5 kV for 4CX3000A, 15 kV for 4CW-100,000E).
Comparison to a 4CX1500B Driver Design
Practical Notes
-
Tuning: Precise matching networks are critical for stability, especially with the higher drive levels.
-
Linearity: The 4CX3000A in Class AB1 ensures good SSB performance; AM uses Class B in the intermediate stage and Class C in the final stage with plate modulation.
-
Legality: 70 kW AM or 100 kW SSB far exceeds 11-meter limits (4 W AM, 12 W PEP SSB in the U.S.). This is for experimental or licensed high-power use only.
-
Tube Limits: The 4CW-100,000E is pushed near its 100 kW dissipation limit in AM mode (70 kW carrier + modulation peaks); ensure adequate cooling and duty cycle management.
-
Verification: Exact output depends on tuning, tube condition, and drive—consult data sheets for precision.
|
Re: Total insanity....500KW 11m amp being built.
One or more of the readers herein have constructed linear amplifiers
capable of more than the two kilowatts input our tickets say is kosher
for the ham bands.
?
We do so in order to solve a problem with the math, (like the
160 meter issue in the Alpha 77-Sx), or with the power plant
design questions, (such as in the Henry 8K Ultra with the
resonant choke dilemma), etc.
?
One thing I discovered is that the fundamental hurdle for me
has always been The Budget. I’ve got most of the bits sitting
in the Parts shed to start in on a 4CPX5,000A amplifier, but
as I grew older I saw that sinking money into another big
Tetrode is not going to get me anywhere but poorer, and to
think about where Ham Radio has gone recently, spending
the Big Bucks on another amp build just doesn’t seem
to be as fruitful as it used to, in days gone by.
?
The bits and pieces to slam together another crusty amplifier
are not as plentiful, and when they are found, the prices for
them are not as cheap as they once were, even on the
surplus distribution channel.
?
Remember Fair Radio in Lima, Ohio? At one time a builder
could find some top-notch pieces, but as time went by,
the drawers and bins held less and less, until the sales
there didn’t keep the lights lit.
?
Even things like electrolytic or oil-filled filter capacitors
are hard to locate any more, and if you want to build
some big iron, you need to get that HV A.C. into the
D.C. world, and there are some budget hurdles
just in that little corner.
?
When the kids from the U/Mo radio club came out to pick
up most of everything from the “big station,” here, they
looked at the tons of components, and their “big” question
was “What do we do with all that?”? “All that,” is not enough,
any more. Ask most any one who continues to build.
?
Hal Mandel
W4HBM
?
|
Re: Total insanity....500KW 11m amp being built.
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.
BBI: "I'm gonna need my goo drop resized to a bunch of 4-ought wires." Electric Company: "Just how acres is yer grow house gonna be??" He's gonna need his own cooling lake, too. Is this guy one of those uber-rich Texas billionaires that's working on those ultra-miniature fusion nuclear reactors? Rather than watch his videos, I'll save my limited time left on this mortal coil to something more productive, like "I Love Lucy" or Abbott & Costello reruns.
|
Re: Total insanity....500KW 11m amp being built.
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.
toggle quoted message
Show quoted text
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:
------
[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
|
Re: Total insanity....500KW 11m amp being built.
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.?
|
Re: Drake L-7 : galvanometer lighting
No one answered my question. Maybe no one had the answer. ? I bought on (Donald is not going to be happy) ?
? These lamps fit perfectly as replacements. In the L-7 they are powered by 5 V AC. I checked that both alternations light up the diode. I chose the amber color, so it would look like the original lamps were filming. ? This may be useful to others
|
Re: Total insanity....500KW 11m amp being built.
Maybe one should check the design of WLW back in the day w/500KW AM
.. and reportedly they had it up to 800KW just for fun.
Just observ'en.
Andy
On 3/8/2025 12:13 PM, Jim VE7RF via
groups.io wrote:
I'm betting this will be an epic failure.? I'll put money on
it.?
BBI, in his infinite wisdom, is
documenting the....'worlds biggest 11m amplifier' on his U
tube channel. Using the 4CW-100,000E water cooled tetrode.
Teaser video.? 7 mins long.? ? ??
Here is part #1.? ? ?It's? ?2 hrs
and 27 mins long.? ? ?
I found 5 x mistakes so far.? ?This
will be an epic failure.? ?It's? good entertainment though.
20 kw of drive for 500 KW? output.?
?Being built in Victoria Texas......in a welding shop.... by
John? De Luna and BBI.? ?
Here is the detailed Eimac spec
sheet for the 4CW-100,000E? ??
IF they are gonna run it in GG, with
both screen and grid bonded to the chassis, the 500 watt grid
will burn up 1st.
If it's gonna be grid driven, well have fun, esp neutralizing
it.? ?If it's? gonna be cathode driven, like a Collins 30S1,?
have more fun.? On the 30S1, the B+ supply, screen supply, and
the bias supply are all in series, which means the screen and
bias supply have max plate current flowing through em.?
I'm gonna assume 3 phase power to run it.? ?With 500 kw
pep out,? it will suck? 800-900 kva.?
Well he did parallel 4 x 2 uf @ 40 kv oil caps for the B+
filter.? ?With 3 phase power, the raw DC from the 6 x leg
rectifier assy has 5.2 % ripple.? ? With 8 uf of filtering and
20 kv,? total energy in the 4 x caps = 1600 joules = dick on a
770 kw? DC input supply.? Any hum will be? 360 hz. (6F on 3
phase).
The tube requires? 20 gallons per minute? at no more than 70
psi...... just for 100 kw CCS anode dissipation.? My garden hose
only does? 4 gpm.? I would be worried about distilled water
purity, and resistance, and possible super heated? steam
explosions.?
100 kw of diss =? 341,000 BTU's? of heat to get rid of.? ?Do the
maths, that will require one helluva BIG air cooled? and
shrouded radiator to dump that much heat.?
Eimac also warns of an X-ray hazard, when operated > 15 kv.?
? ?The cavity needs to be lined with .020" lead sheeting.?
?
?The folks? building this amp? are in for a rude awakening.?
? They are talking about 250 kw CXR, and swinging to 500
kw....and pep output close to a megawatt.? ?When tuned for close
to a megawatt, the tank eff? with just the 250 kw CXR will be
aprx 25%.? ? Anode diss = 750 kw.? ?Tube rated for 100 kw
diss.??
Calculate the RF? current through the tank coil, and it's aprx?
225 amps.? Shit, even Kintronics doesn't make anything that
big.? ?3" tubing would run hot.? ?The RF current through the
tune and load caps is beyond horrendous.? ?205 amps through the
load cap.? 102 amps through the tune cap.? 80 amps into the TR
relay? + coax.? ?You would have to parallel 3 x Gigavac G52?
spst vac relays to handle that current. 5.7 kv peak across the
connectors, load cap, and TR relay...and coax....with a 1:1?
swr.?
Toss in sundry items like the plate block cap assy, which will
have? 100+ amps through it....... which in this case would have
to be a fixed ceramic vac cap....and this will be end up being?
the project of the decade.?
This amp would work....if they backed down on the insane power
levels.? Dunno what they are gonna use for an ant,? but if it's
a gamma matched yagi with a vac cap, they will be in for more
surprises.? ?The rotor loop will be an? engineering feat in
itself.? ?CM choke....good luck with that, not happening.?
IF they can pull it off, hats off to em.? IMO, they have bitten
off more than they can chew.?
--
"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
Broadcastify Train Scanner:
Youtube Channel:
|
Re: Total insanity....500KW 11m amp being built.
Freakn Crazy!?
Well, if anyone from that specific genre that coild seriously attempt and build such a beast, it would be Luke that could possibly? get away with it.
I wonder who has the.deep pockets to fund this folly??
I never thought of this guy as being any bit of a dummy. He always has seemed fairly smart and I have assumed that he had a good idea of what he is doing. Definately seems sincere and seems like he has enough smarts to understand and figure things out. But you really gotta question whay goes thru a guys head to do some crazy stuff like this and be all into that whole CB style of radio...?
It certainly seems as if there is a few decent talents rising from that crowd and so much more mamy of them aspiring to build stuff. I have found that there are few places on the internet that cater to big homebrewed RF amps without some of these guys being at the top of that game.?
There are some pretty crazy over the top worldwide dx contest stations. I suppose I am biased and can have a greater understanding for a multi-million dollar antenna farm and a bank of flagship contest gear quarter of million watt carrier single 11 meter band amplifier, i kinda just dont get it??
Do you think that BBI has just gotten too full of himself and is just talking a bit out the side of his neck?? Really two and a half hour video??
I will have to check this out. I can always ff thru parts of video. I believe he might actually start this project, will he complete it? I dunno? He must have a benefactor from Dubai or something of that sorts... pass the popcorn please.
|
Total insanity....500KW 11m amp being built.
I'm betting this will be an epic failure.? I'll put money on it.?
BBI, in his infinite wisdom, is documenting the....'worlds biggest 11m amplifier' on his U tube channel. Using the 4CW-100,000E water cooled tetrode.
Teaser video.? 7 mins long.? ? ??
Here is part #1.? ? ?It's? ?2 hrs and 27 mins long.? ? ?
I found 5 x mistakes so far.? ?This will be an epic failure.? ?It's? good entertainment though.
20 kw of drive for 500 KW? output.? ?Being built in Victoria Texas......in a welding shop.... by John? De Luna and BBI.? ?
Here is the detailed Eimac spec sheet for the 4CW-100,000E? ??
IF they are gonna run it in GG, with both screen and grid bonded to the chassis, the 500 watt grid will burn up 1st.
If it's gonna be grid driven, well have fun, esp neutralizing it.? ?If it's? gonna be cathode driven, like a Collins 30S1,? have more fun.? On the 30S1, the B+ supply, screen supply, and the bias supply are all in series, which means the screen and bias supply have max plate current flowing through em.?
I'm gonna assume 3 phase power to run it.? ?With 500 kw pep out,? it will suck? 800-900 kva.?
Well he did parallel 4 x 2 uf @ 40 kv oil caps for the B+ filter.? ?With 3 phase power, the raw DC from the 6 x leg rectifier assy has 5.2 % ripple.? ? With 8 uf of filtering and 20 kv,? total energy in the 4 x caps = 1600 joules = dick on a 770 kw? DC input supply.? Any hum will be? 360 hz. (6F on 3 phase).
The tube requires? 20 gallons per minute? at no more than 70 psi...... just for 100 kw CCS anode dissipation.? My garden hose only does? 4 gpm.? I would be worried about distilled water purity, and resistance, and possible super heated? steam explosions.?
100 kw of diss =? 341,000 BTU's? of heat to get rid of.? ?Do the maths, that will require one helluva BIG air cooled? and shrouded radiator to dump that much heat.?
Eimac also warns of an X-ray hazard, when operated > 15 kv.? ? ?The cavity needs to be lined with .020" lead sheeting.?
?
?The folks? building this amp? are in for a rude awakening.? ? They are talking about 250 kw CXR, and swinging to 500 kw....and pep output close to a megawatt.? ?When tuned for close to a megawatt, the tank eff? with just the 250 kw CXR will be aprx 25%.? ? Anode diss = 750 kw.? ?Tube rated for 100 kw diss.??
Calculate the RF? current through the tank coil, and it's aprx? 225 amps.? Shit, even Kintronics doesn't make anything that big.? ?3" tubing would run hot.? ?The RF current through the tune and load caps is beyond horrendous.? ?205 amps through the load cap.? 102 amps through the tune cap.? 80 amps into the TR relay? + coax.? ?You would have to parallel 3 x Gigavac G52? spst vac relays to handle that current. 5.7 kv peak across the connectors, load cap, and TR relay...and coax....with a 1:1? swr.?
Toss in sundry items like the plate block cap assy, which will have? 100+ amps through it....... which in this case would have to be a fixed ceramic vac cap....and this will be end up being? the project of the decade.?
This amp would work....if they backed down on the insane power levels.? Dunno what they are gonna use for an ant,? but if it's a gamma matched yagi with a vac cap, they will be in for more surprises.? ?The rotor loop will be an? engineering feat in itself.? ?CM choke....good luck with that, not happening.?
IF they can pull it off, hats off to em.? IMO, they have bitten off more than they can chew.?
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Re: Original GM3SEK/G3SEK Tetrode Boards
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Drake L-7 : galvanometer lighting
I'm going to bore you again with my L-7. The 4 lamps that light the two galvanometers are out of order (strange). They are powered by the 5 volts (alternating current) of the filaments of the 3-500Z. ? Have you replaced these fairly classic bayonet lamps? ? 
? by LED lamps?
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Hello ? Thanks Alek for resuming the dialogue. You are the only one who has reported this risk of non-degassing to me. Like me, you are faced with a reduced regulatory RF power ? You had told me /g/ham-amplifiers/message/40898 that the gettering was done by the anodes. If you run 500W PEP only, your tubes will quickly become gassy. They have no separate getters. The gettering is done by the anodes and so they must become red during operation to keep them healthy. This happens in Australia as well where we have 400W PEP limit. At that level, the anodes never get red, so the tubes fail very quickly. You will need to exercise your amplifier at full power regularly to ensure healthy tubes. This risk does not seem to worry the other participants at all. ? Your point is confirmed in this document https://www.w8ji.com/Amplifiers.htm The fastest way to ruin a 3-500Z or other glass electric grid tube is to never expose the anode color for an extended period of time! Storing a 3-500Z tube for many years without using it almost guarantees that a breakdown will occur the first time a high peak voltage is applied to the anode. Since the tubes had not been used for 15 or 20 years, I did not want to expose them to the risk of arcing due to imperfect degassing. So I came up with a solution, which I have outlined, to make the plates glow under a relatively low anode voltage by applying a positive voltage to the grid (actually positive to the cathode). ? I proposed ·???????? To use the SSB position 2500 V 220 mA only to periodically degas the tubes and this without RF ·???????? To use the CW position 1700 V 175 mA during real SSB traffic with RF=500W ? Eventually, I can find a solution so that in CW position the anode current is lower. De la part de Alek Petkovic via groups.io
贰苍惫辞测é?: mardi 4 mars 2025 10:43
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Hi Francois.
I would suggest you leave it as zero bias, without any diodes. As
you say, with just 500W PEP output, the tubes will not get hot
enough to de-gas.
Your solution of running the amp at 220mA without drive is very
good and it will ensure that your tubes are always healthy.
So keep it as it is and don't change the bias. It will work fine
for your application.
73, Alek VK6APK.
On 3/03/2025 11:39 pm, Fran?ois via
groups.io wrote:
toggle quoted message
Show quoted text
So
I went to full voltage tests with the 2 tubes in place. With
zero bias I measure
?
·????????
CW
voltmeter 1700 V measures 236*8=1888 V intensity 175 mA; the
tubes do not redden 298 W (2 tubes)
·????????
SSB
voltmeter 2500 V measures 329*8=2632 V intensity 220 mA; the
tubes redden 550 W (2 tubes)
?
In
low voltage tests 231 W (plate current 390 mA under 592 V)
for one tube redden. The result therefore seems consistent.
?
In
my country (France) the power is limited to 500 W.
·????????
I
could operate the L-7 on the CW position and by limiting the
excitation 500 W RF output.
·????????
Periodically,
run the amp in SSB position, without RF, with just
the 220 mA quiescent current to make the tubes glow and thus
maintain optimal degassing.
?
I
am concerned that by placing diodes in the cathode circuit
to bias the grid slightly negatively, the quiescent current
in SSB mode will not be sufficient
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Hello ? Okay, I got it. It's the receive polarization that I didn't understand. Now it's ok. ? What quiescent currents should I get to and in what mode (SSB/CW), knowing that I want to output 500 W PEP?
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Draw it and take a picture and post that????
Can one of u folks pse help me out here, as I have no clue how to post a simple diagram on here.?
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HaL Mandel
Mike Peace
K6LPM