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Fully operational and wired for 110V operation, has latest firmware version installed. $2500.00 shipped to any US destination (Buyer pays add additional insurance if desired) Includes a 6 month defect guarantee from my ACOM authorized US service/repair center which is now in the process of relocating due to a storm-water disaster emergency so tt this time can only accept a bank wire as Payment. The funds will expedite the relocation process greatly, thanks for looking. Steve Hearns KA2PTE Pending Honorary USMC Corporal Technotronic Dimensions [USA] WWW.TECHNOTRONIC-DIMENSIONS.COM E-Mail: Steve@...

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. https://www.youtube.com/watch?v=jbD0wEPVv3s Here is part #1. It's 2 hrs and 27 mins long. https://www.youtube.com/watch?v=yUa54WgAzEI 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 https://www.relltubes.com/documents/Datasheets/4CW100000E.pdf 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.

Hello Could you help me validate the attached schematic? The goal is to negatively bias the 3-500Z grid using a Zener diode, without passing the cathode current through the Zener diode. The components added to the original schematic are shown in red. The biased wires in the diagram have already been set up in a previous experiment to bake the anodes under low anodic voltage. With the original zero bias wiring, I observe, at rest, 250 mA under 2400 V (2x300 W) which seems exaggerated to me. I'd like your opinion on this schematic before I do something stupid. Could you add to the diagram the diode(s) to be installed in order to limit the effects of an arc which is always possible in a 3-500Z. -- F1AMM Fran?ois

Hello On my Drake amplifier, I would like to install additional hardware using existing threaded rods (3-500Z support spacers). If I measure the thread diameter, I get a reading of 3.3 mm (1/7 inch). The existing nuts measure 6.1 mm (1/4 inch) across the flat. Can you tell me the US thread size for this type of thread? -- F1AMM Fran?ois

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? -- F1AMM Fran?ois

Hello Now that both of my 3-500Zs have been de-gassed, I have a new question. · In the L7 (Drake) the bias is at 0 volts · In the Kenwood TL-522 it is -7.5 V as shown in the following diagram We read a bit of everything http://amfone.net/Amforum/index.php?action=printpage;topic=46759.0 The objective is to put the L-7 into operation in SSB at medium power. -- F1AMM Fran?ois

Hello I am in the process of putting a Drake L 7 amplifier back into operation. I was advised on this forum to bring the anodes of the 3-500Z to red to maintain the quality of the vacuum. After removing the screens to check the equipment and the filaments, I realize that once the screens are put back, there is no way to observe the anodes of the 3-500Z; everything is shielded (no window). How do you observe these anodes? -- F1AMM Fran?ois

The output relay in my Ameritron AL-1500 needs to be changed. I checked with MFJ since they are still selling some Ameritron replacement parts, but no luck. From the user manual, this is "RLY1" and its Ameritron part number is 408-6139. This is a 3PDT, 10A, 12V DC through hole PCB mount relay. Two of the poles are used for RF switching and the third is used for another function. I've searched on Mouser, Digikey, Allied, Newark and E-bay websites without finding anything that might be a satisfactory replacement. Ideally, an original replacement part would be found. This would allay my concern about the contact materials which should be gold or gold plated for the two NC RF contacts to ensure good contact when receiving. Suggestions would be appreciated. 73 de Riki K7NJ