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OK, the 2 (brand new) x Ameritron ALS-606's only put out barely 300w on 6m (and only 400w on 75m). Ready to tear our hair out. Plan C was the new ALS-1306...which actually does work. Cut to the chase. 10 kw CXR out with aprx 600 w of drive. (brand new Coaxial dynamics 25-60 mhz, 10 kw calibrated slug). Line section with the 10 kw slug / meter has the pep kit installed. Line section with 1 kw slug, between ALS-1306 and input to the tube amp....(to measure drive into tube amp). Line section with 25 watt reflected slug between ALS-1306 and input to tube amp....(used for tweaking the PI tuned input, with it's 2 x air variable caps). Jennings ceramic vac tune cap....and a Swiss made (Comet) ceramic vac load cap. All testing done on 50.125 mhz. The big dummy load consist of 32 x 1600 ohm globars (18" long) in parallel to make the 50 ohm commercial DL. 7-16 Din on output of tube amp and also downstream. B+ sagged quite a bit with a CXR. But with every 1 volt AC going in, he has aprx 25 vdc coming out. The line sagged 6 vac from the street, so we lost 150 vdc. Then another 125 vdc through the 40 ohm glitch R. No load B+ was 5900 vdc. Loaded to 3.125 amps of DC plate current, it drops to just 4300 vdc. (It would have been 4575 vdc without the above pair of V drops). Then you have the typ 5-10% drop in the B+ supply anyway. Then the small V drop across any 2 of the 4 x strings of diodes in the FWB. On SSB / CW, it drops very little. This is the difference between a static load....and a dynamic load. Total of 30 uf of filter caps (2 x 60 uf @ 4 kv oil caps in series), so we don't have a huge amount of energy stored in the caps. (522 joules). Plate current = 3.125 amps Grid current = 500 ma Loaded B+ = 4300 vdc DC input = 13,437 watts. Power output = 10 kilowatts. Anode Dissipation = 3437 watts. Eff = 74.4 % Bias can be toggled between 50 ma idle and 200 ma...(Class AB). (toggle switch changes the tap on the series diode string, used for bias). Special thanks to John Lyles, K5PRO, for his assistance on Saturday, conducting some SRF (self resonance freq) tests on some doorknob caps, on his Vector impedance meter. (Old HP 500 khz to 108 mhz unit). We changed out the bypass caps at the cold end of the fil choke. Scott designed and built the HV supply. I designed the unique RF deck. (Scott also built the RF deck). The 80-15m 3CX-6000A7 amp will be the next project....already in the works. I have most of the RF deck designed. https://www.youtube.com/watch?v=W87ySwzL_-I Later.... Jim VE7RF

Hello! Does anyone has the plan for tuned input mod for Dentron Clipperton L ?. I'm also searching for a meter to replace. all the best, s52ow Tilen

On the 3CX-6000A7 triode, the tube is 1st hi-pot tested between the anode and grid (and a temp short between grid and cathode). Then the polarity is reversed. Leakage should be < 5 ua in both cases. On a 3CX-6000A7, a good tube will hi pot test to 25 kv. (On a 3CX-3000A7, it should hi-pot test to 20 kv. A good 3-500Z should hi-pot test to > 12 kv) Then the tube is hi-pot tested between the grid and cathode (and a temp short between the grid and anode). Then the polarity is reversed. A good 3CX-6000A7 should hi-pot test to 5 kv (same 5 kv with the smaller 3CX-3000A7).The hi-pot tester has to be a DC type...and also incorporate current limiting. It's an invaluable tool. It's also used to test vac caps, (fixed and variable, glass and ceramic), vac relays, connectors, disc caps, doorknob caps, and coax connectors, and also cables...and anything else you can think of. It just saves a lot of grief..... knowing that the parts you installed meet spec. (I use the small, compact hi-pot tester sold by Tom Rauch, W8JI, through his business, CTR engineering. It's a 0-15 kv DC unit, and incorporates dual current limiting. It operates on anything from 12-18 vdc. That comes in handy for a hamfest, etc. The unit also has a red led on it to depict leakage current. I use a Fluke 87 DVM, in series with the return leg, for a more accurate reading of leakage current. Both methods work). https://www.youtube.com/watch?v=93kUcNIaps0

Here, all the final wiring has been completed, including the B+ between HV supply and RF deck. Top lid of the HV supply, where the blower outlet is located, was modified, with 4 x pieces of 1" x 1" x 16" thick angle aluminum. New angle pieces located between the blower flange, and underside of the top lid of the HV supply. These 4 x angle pieces will engage the mating air inlet on the bottom lid of the RF deck. 3/8" gasket material sandwiched between the 2 x flat surfaces. This ensures an airtight fit. The angle pieces protruding up, and into the RF deck bottom lid.... 'locks' the 2 x cabinets together, so the RF deck on top can't move about, when it's sitting on the HV supply below it. HV supply is on casters...and is easily rolled about. Testing on the HV supply begins next week, time permitting. Then testing the various misc supplies inside the RF deck, vac relays, fil variac, blower, blower interlock etc, etc..... then the entire combo together, as one ensemble. Tube airflow requirements are 204 cfm @ .4" pressure (with a 104 deg F inlet air temp) for the rated 6 kw CCS anode dissipation. The EBM Papst blower used on this 6m amplifier is rated for 320 cfm @ .9" pressure. With the 50% increase in airflow, the anode dissipation is increased by 20%....to 7200 watts CCS. With a more sane 77 deg F inlet air temp, the anode dissipation is further increased to 7900 watts CCS. When the cfm is increased by 50% (1.5), the pressure must be increased by the square of the cfm increase. (1.5 x 1.5 = 2.25). 2.25 x .4" = .9" All that airflow is 1st drawn in through the pair of fingerguards on the HV supply, and past the various HV components, plate xfmr, fil xfmrs, etc, before it gets sucked into the blower intake. That ensures both the HV supply and RF deck remain cool at all times. IF the blower ever failed, the pressure interlock switch would release, and ALL voltages are removed asap. In normal operation, the air pressure in the plenum has to be normal, before any voltages can be applied. IE: both the RF deck + mating HV supply will only function IF the blower is running. The next project is currently in the design phase. Consists of a 3CX-6000A7 operating on 80-40-30-20-17-15m. (6 bands). A variation of that is 160-80-40-20-17-15m. (6 bands). This will be bandswitched (progressively shorting triple wafer model 88/85 switch / model 90 switch) and a bandswitched, manually tuned, PI tuned input. Higher B+ voltage used. Obviously far more complicated than the 6m amp. 10 kw CCS output on data modes / 12 kw pep output on SSB + CW. Stay tuned for further updates. https://www.youtube.com/watch?v=7LKhgOdXVsY

I'm looking for the procedure to peak the tuned input of this amp, it has 2 ceramic trimmer caps at each band circuit 10-160. If anyone can help me with info on how to fine tune the input circuits of this particular amp I'd greatly appreciate hearing from you. I'm not having any issues that I know of but just want to see where its at.

Power supply finally completed. RF deck sitting on top of B+ supply. This is a superb video, that depicts how it all interconnects together. I made an error on the Part 27 writeup. The oem thin aluminum top cover of the larger B+ box was temp used as a template, and laid on top of the new, 1/8" thick, 6061-T6 top cover for the B+ supply. The oem cover used 6-32 screws around it's circumference. The 2 x identical sized sheets were temp overlaid, then C clamped in several places, (between holes), then new holes drilled out. The new EBM Papst blower is a model G2E160-AY47-01. It's heavy, 4 kg (8.8 lbs). Rated for 305 cfm @ .9" pressure...when run on 230 vac / 60 hz. That weight hangs from the new, thicker top lid. Here is the data sheet for the blower. (scroll down for the 60hz performance curve). https://www.mouser.ca/datasheet/2/120/ebm_papst_G2E160AY4701-1879431.pdf Here is the latest part 27 video. Testing will begin next week, time permitting. https://www.youtube.com/watch?v=AO5viYysNsM

Here the German 330 cfm @ .9" EBM Papst blower is installed below the top cover of the B+ power supply. The oem thin top cover of the B+ supply was re-enforced with an identical sized cover, but 1/8" thick 6061-T6..and placed above the oem cover. The blower sits right above the paralleled pair of fil xfmrs. The 3CX-6000A7 requires 204 cfm @ .4" pressure...with a 40 deg C (104 deg F) intake air temp. I carefully calculated with 306 cfm @ .9" pressure, anode dissipation would increase to 7200 watts CCS. And with a more sane 25 deg C (77 deg F) intake air temp, the anode dissipation would increase to 7900 watts CCS. It's an easy tube to cool, due to it's 6.125" OD anode cooler, and it's small diameter...'ceramic stem'...(identical to a 3CX-3000A7). IE: the under fin area of the 3x6 tube is big...a lot bigger than the smaller 3x3 tube. There is a pressure interlock switch incorporated into the RF deck plenum. Until the blower spools up to normal pressure, the interlock has been configured such that the B+ supply will not power on, nor will the filament supply, nor can the RF deck be keyed. It's all carefully interlocked. And if the blower failed during normal operation, the 240 vac primary of the B+ and Fil supply and the key line all go open. IOW, it's a fail safe circuit. https://www.youtube.com/watch?v=ZCwQVE6WA0o

I have a pile of old power supplies I found buried in my back closet. One of them is an old full wave, but not a bridge. One of the stud rectifiers shorted blowing the filter cap up and taking out the 3055. I'm considering taking full wave bridges on each side of the transformer and connecting the positives and negatives together, or should I just get two large 1N devices instead? OTQ, I didn't forget you and the old modems. I've just been busy. On another turn, Anyone ever play with the tuners that are in old VCRs? Is it worth seeing what I can do with one? TIA -Scott

Here the HV wiring is all completed. That's a lot of components in total.... in a big box. The pair of finger guards is to allow intake air to flow past the 17 kva ccs plate xfmr, caps etc.... then into the intake of the EBM PAPST 330 cfm @ 1.0" squirrel cage blower, that will hang below the mating RF deck..with RF deck sitting on top of the newly completed B+ supply...via a membrane between the two cabinets. IE: the blower will hang into the B+ supply. Here is the short 5.30 min video depicting the final HV wiring. https://www.youtube.com/watch?v=LmfoBsAvTIc

I'm sad to report that Leigh Turner, VK5KLT, a regular and very knowledgeable contributor on this forum has become silent key, apparently some time earlier this year. In my last correspondence with him late last year, he reported that he was having serious health issues. In all my dealings with him I found him to be decent beyond reproach, highly intelligent and very skilled in the hobby. My wife and I were going to drive to VK5 around this time last year. Included in that trip would have been a long overdue eyeball QSO with Leigh in North Adelaide. The Covid situation put paid to those plans. Thanks and rest in peace Leigh. 73, Alek VK6APK

Here in Part 25, the series pair of 20 ohm @ 300 watt CCS 'glitch resistors' are finally installed, along with the FWB diode board assy....and also the BUSS HVU-3, HV fuse. HV fuse installed in a pair of silver plated fuse holders, that also have end retainers built into the fuse holders. Once fuse inserted into the fuse holders, it does not budge. It can't migrate out in either direction, due to the end stops. The end stops also allow the HV fuse to be mounted vertically, or horizontally. The 40 ohms of total glitch resistance LIMITS any fault current to a 'safe' value, while the HV fuse INTERRUPTS the fault current, and stupid fast, like < 2 msecs. 6000 Vdc / 40 ohms = 150 amps of fault current. 150 amps of fault current will open off the fast, 3 amp rated BUSS HVU-3 fuse super fast...event over. The drawback to the 40 ohm glitch resistor, of course is the 120 vdc V drop across it, when 3 amps of DC plate current flows though it. There is no fix for that. https://www.youtube.com/watch?v=USQ3JqGfj7g

In Part 24, the new FWB rectifier board is built on drilled out perf board. 15 x 1kv @ 10 amp diodes are used in each of the 4 x legs. (60 x diodes in total). https://www.youtube.com/watch?v=ch4lRhRi6-k

Due to the massive backlog of amps in for repair, work on the 6M amp has been delayed. However, some progress made yesterday. Here Scott shows the Installation of the bleeder / Equalization Resistors, meter dropping resistors and plate voltage meter. Still to be installed in B+ supply, is the rectifier board, glitch resistors, HV fuse etc. https://www.youtube.com/watch?v=KxuHVMu01QQ

I didn't realize Will Matney was SK....and that was yrs ago. Didn't he write a book about magnetics ? I just found out abt Will, from another forum last week. He used to post on here quite often.

It has been suggested to me that a 4-250 or 4-400 could be used in a grounded grid amp that is designed to use a 3-500Z. I wonder if anyone here has experience of doing this as I am in the process of acquiring a home brew amp that originally used 2 x 3-500Z. I see the base and filament requirements are the same but can the grids all be strapped together and directly grounded? What would be the bias requirements for ssb operation and cutoff in Rx to achieve by taking the filament CT above ground? Mike. Mike Fleetwood Canberra Australia and Sidcup UK. Worldwide email address is: mfleetwood@...

I have been studying the Service Manual for my TL922 in connection with the bias arrangements. On Page 6 it says "In ssb mode the zener diode is shorted by S3 lowering distortion" Looking at the circuit diagram S3 only appears to change the HT supply at the transformer, lowering the voltage to the rectifiers for CW and from what I can see the 7.5 volt zener diode is in circuit for both modes. Looking at my amp that does appear to be how it is. I thought the 3-500Z was a zero bias triode so just wondering how this all figures out? Mike VK2AMF. Mike Fleetwood Canberra Australia and Sidcup UK. Worldwide email address is: mfleetwood@...

Does the Alpha 86 International model have a manual for it? 73 Ron KK7GO