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Equipment Interconnect cables
17
Hello, In HF service, when running interconnect coax cables from an amplifier outbound, I have always used RG-213 or equivalent from the amp to whatever accessories I was using at the time such as a monitor scope, power meter, ATU, etc. then on to the antenna. Since the interconnect cabling are usually very short lengths, is it acceptable today to use RG-8X for this when running high power or is it standard practice to use the heavier coax? 73, Garry
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Amp builders might be interested in this like 20 dollar gadget. Its marketed as a IGBT tester however it can test any component to 3700 volts upto 5ma. https://www.ebay.com/itm/296767679099?_skw=igbt+tester&itmmeta=01JCF3RQH1VS60KP7SWVR49KF5&hash=item4518bb6a7b%3Ag%3AmPEAAOSwofVnF3Fx&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKkTu8qSspIOpj1Pr%2FkVy2zBH0DDKWrHoBF6DV%2FvDTdUo%2FroUqWTtQDQ1pPLUiVetndgzphdCZp2U2sBLo6monVSnaeG%2BhS0VVQsORMQSsjhfHJRr2lJURzuo33foGqSYJKg7ViuCIwDbgFnYuIJhUoxVhSWEofoPou8ZftmUpkZf4ZSsl90ttfizhkizjAUzOmt526RaEpGfe4u%2FUge6bd21v3EaNxjcY8MBgQUSRx7NN29svRs7p2aNplSB81ckkJrn3BkkvTV9Tj4LyN3ZPkf%7Ctkp%3ABFBMzvji4-Nk&var=594575090972 I have used it to test MOV's Gas tubes, Zeners, leds, capacitors, rectifier diodes, coax connectors etc etc Its really handy when you dont want to pull out the big hypot It operates in two test modes. You connect the device and just push the button and it will indicate the voltage that the DUT flashes over. The other mode is that you can disconnect the DUT and dial in the expected working voltage then it will test at the dialled voltage. I generally start on low voltage and increment up till I hit the flash voltage. The voltage output is very accurate. You can find them on all the Chinese auction sites Its been a fun toy. Maybe one of these days they will make a 10 or 15KV version which would be handy. You can hear from the whine that its using one of those HV switchmode booster modules. It sources 5MA so you can test strings of series zeners when wired in reverse. Very handy.
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I'd like to know if any of you have suggestions as to what caused this HV arc to chassis and hopefully, what to do to prevent it in the future. Amp is a TenTec Centurion. It was at idle when the arc happened; no RF applied. The glitch resistor took the brunt of the discharge, thank goodness. I've replaced it, even though the original still measured the correct resistance, it was visually damaged. The event spooked me...new pair of 3-500Z tubes was in the amp; no apparent damage. The insulator appears to be made of fiberglass. The glitch resistor is on the opposite side of this aluminum panel. The HV feeds through from the resistor via the machine screw. Any thoughts? Thanks, Robin Midgett K4IDC
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During my move from the city to an extreme rural area, I had a Henry 2K-4, along with a spare set of 3-500Zs, gifted to me. I'm presuming the 2K-3 is a more modern looking 2K-3 and I have a '7300, so the thread combining the 2K-3 relay update and the 7300 "tail" is interesting. I am the 3rd keeper of the 2K-4 and was told it was bought after demonstrating its functionality, but "something happened on the way home". I've looked it over closely and the only things I've found were a wolf spider that jumped onto my hand (I said a couple of bad words), a NEMA 5-15P (regular 125VAC plug) on the end of the power cord, the amplifier internally strapped for 240VAC and what seems like a decade of dust covering everything. The dust is now gone, as is the wolf spider. So my hope is that someone had a Halloween special regular outlet hooked up for 240VAC, but everyone else has just been plugging it into a correctly wired 125VAC outlet.. I have not powered up the 2K-4 due to a lack of a 240VAC circuit in the shack. I have the stuff to add a 60A/240VAC sub-panel in the shack, but...other projects are taking priority. Eric WB6TIX
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Plate & Load
6
Been an AMP user for almost 50 years. But have a question. The Plate/load/coil match the tube(s) output impedance to the desired antenna impedance typically 50 ohms. Just like a tuner changes a non 50 ohm antenna to 50 ohms. But I just thought of this. in the antenna tuner the two caps can be and usually are all over the place. And their tuning is typically rather broad. the caps are not super tight. But in an AMP The Plate control is very critical and narrow in optimum setting. And It's level of "C" is almost predictable. You KNOW the 40 meter will have less "C" than 80 meters. And so on through the bands. The load cap is almost in the same position and in almost every amp I have had the optimum was rather broad. Why? Joe WB9SBD
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Econco 3cx3000 Rebuild cost
5
Anyone had any experience in getting a 3cx3000A7 rebuilt with a supplied Eimac Dud? I would be curious if its worth the cost and what the cost is compared to buying a new Penta 3cx3000. I have a few 3cx3000A7 duds from Henry RF heaters as well as 3cx3000F1 ones which I am told Econco can rebuild as a 3000A7. Henry
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Electrical Improvements
10
The revised electical laws regarding grounding of appliances and not using their chassis¡¯ as a.c. returns hit home one day when I was cooking . I was stirring something on the electric stove with a stainless stirring spoon and reached for the ¡®fridge door so I could retrieve an ingredient, and there was some sort of fault and I got knocked on my ass. The fault voltage, later measured was 65 volts from the chassis of the electric stove to the chassis of the refrigerator. I showed this all to my LL¡¯s son and he took a chance on touching the pair of appliances at the same time, too. Sears was there the very next day with a new ¡®fridge and a new stove. Bless someone¡¯s heart¡. Hal Mandel W4HBM
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TL-922A transmits when switched from standby to operate.
19
My TL-922A, which has been working flawlessly for quite some time, is now going into transmit mode as soon as the switch is changed from standby to operate. What has changed is I rearranged the shack, so had all equipment disconnected for two days. The amp stood on end over in the corner of the room for that period of time. Reconnected everything yesterday, and used the TS-890S barefoot for a contact with C21MM (Nauru). The amp was connected but not powered on. When I went to use the amp this morning, this behavior showed up. I have disconnected the RELAY and ALC connections. No change. Powered off and on several times, No change, Disconnected the RF INPUT cable from the TS-890S. No change. Any ideas about what might be causing this and how to fix it? -- Jim McPhee Placitas, NM W5ABA
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RM Italy bla-350 plus reviews
Thinking about buying a bla-350 to use with my ten-tec Omni VI plus. Has anyone used a 350? Is it a decent amp? 73's Mike
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Ok the fellow who gave me the SB-200 to repair now has it in his possession again with no smoke! However, he said that the antenna relay is hanging up just like the problem he has on his AL-80. I know for a fact that it has the Harbach ¡®soft-key¡¯ keying interface installed. The common denominator is his FTDX-10. I am not familiar with that rig at all. I understand it is possible to use 2 ports on the back as a key line. Having said that, is there a software setting that sets the key line or would keep it high? He says he has to shut ¡®everything¡¯ down before it returns to normal. I won¡¯t be able to visit his QTH and examine it myself until sometime in Oct. Is there something else I should also check out when I do go? He is a smart ¡®cookie¡¯ but sometimes he can¡¯t see ¡°the trees for the forest!¡± Thanks in advance. Mod-U-Lator, Mike(y)/W3SLK
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12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 20
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 20 Misc info on how this project goes together. Bottom of RF deck cabinet will hold the blower, fil xfmr, chain drives etc, etc. The HV supply will reside in a separate cabinet, with the pair of 150 lb magnespec plate xfmrs, FWB assy, contactors, 20 x 2500uf lytics etc. https://www.youtube.com/watch?v=-BOYflhiVcE
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RMItaly BLA600
10
Fixing one of these up, had a blown LDMOS FET now ok on CW, but SSB trips a lot of error protect faults related to I think the peak power during modulation input to the amp. It claims > 25W is what brings it into protect and my Kenwood 930S trips it in SSB no matter how low the output is. My KW 850S has better Carrier and FR out controls, so I can bring it down much lower and it seems to be ok with that rigg. This is running on 110V hookup, I get about 450W CW carrier, and most I can see on the average analog power meter is like 200W and thats almost full bars on the amps power bar meter on the front panel, so I am left to believe this is its intended operation without using ALC? The owner of the amp uses an ICOM 706MK2 with no ALC on the AMP, but I believe it does have an ALC output. I have never ran an amp with the ALC from the rigg, but its suppose to I guess limit the spikes I am seeing which also reduces the buckshot side splatter from the inherent IMD they produce? -- Steve Hearns [ KA2PTE ] Technotronic Dimensions, VT [USA] WWW.TECHNOTRONIC-DIMENSIONS.COM E-Mail: Steve@...
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12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 19
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 19 The RF deck is finally completed !! Bias diodes installed.....and also the hb ferrite loaded plate choke. (393 uh, and series resonates at 17.650 hz....and also 30.1 mhz). A pair of .01uf @ 30 kv disc caps installed at cold end of plate choke...along with a 750 pf @ 15 kv doorknob cap assy. (2 x 1500 pf @ 7.5 kv doorknobs in series). This is a thing of beauty, but was one helluva lot of work + effort. 160-80-40-20-15m....that's it. Output side has all been mapped out. No padding used on either vac tune or load caps. On the input side, air caps are padded on 160m only. Vac relay's used for the input + bias, and also 2 x more in parallel for the 12 kw output. Everything is rated for 100% duty cycle, brick on key CXR. Next up is the hb 7500 vdc B+ supply....which gets installed at bottom of the same rack...along with the fil xfmr and Ebm-Papst 330 cfm blower etc. 20 x 2500uf @ 450 vdc lytics will be used in series. (125 uf @ 9 kv)...along with a pair of 7.5 kva CCS identical plate xfmrs, etc. On a side note, I made up several of those ferrite loaded chokes. On my own choke, I made it a bit longer, and it series resonates @ 16.2 mhz.....and also 27.99 mhz. The 16.2 mhz is midpoint between 20+17m. On Scott's amp, due to height restraints, I had to make the choke shorter..... and his 1st series resonance @ 17.650 mhz is midpoint between 20m + 15m. Once the B+ and fil supply are built + installed, final testing and calibration can be done. https://www.youtube.com/watch?v=9ZUrb3vqfSc
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3CX1200Z7 maximum safe grid current
3
I have an AL-1200 with the 3CX1200Z7. The tube has a grid dissipation rating of 50W, but I've found no spec for maximum grid current. On page 5 of the AL-1200 manual it says do not exceed 300ma during normal operation of this amplifier. On page 14 in step 11 of the CW tuning procedure it mentions both 300ma and 250ma. I have been running my AL-1200 at 200ma grid current because I don't want to risk damaging the tube, but I can't get 1500W output on any band at 200ma grid current. I would like to know what is actually the maximum safe grid current for operation of this tube. I noticed the last time Ameritron was advertising the AL-1200, the price was for an amp without the tube. I took this as an indicator that the tube is no longer in production. Is this true? Is anyone re-building the 3CX1200Z7? Thanks! 73, John, K9MM
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Ameritron ALS-1406
3
I have only had my 1406 for a month now. It is performing well. Some one told me that they had a 1406 and that it would do 1500 watts easily. I just tried mine for the first time at that power level. I had a 20 minute qso. They told me that my audio sounded find and the amplifier did not kick out at that power level. Apparently Tom made a very good design, ...again. I accidently got it up to 1600 watts and it did not kick out. I will not do that again. The size of this amplifier with it separate powers supply is huge compared to the other 1500 watt SS amps being sold. I think it is double or triple the size of a Mercury or Acorn SS amp. I did not want to buy either of these other amps because they had computer screens to show the power, VSWR, etc. I did not want something else that could go wrong. The 1406 is just knobs and meters. I prefer that. If someone else here has a 1406, I would love to hear their own comments on its performance for them. My serial number on the 1406 is 00015. :-) Apparently there were few made before they closed.
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Yes, it's a possibility that those capacitors are bad but more likely is that the 80m and/or 160m contacts on the band switch have been burnt away. It is quite common on the 2100Z. Shine a light down into the band switch and check every contact carefully. From memory, it is not easy to pick the burnt contacts at first glance. I can add that it is not a fun job to change the switch. I have done a couple over the years and I'm not keen to do it again. 73 and good luck, Alek VK6APK On 9/08/2024 3:44 pm, vk3acu@... wrote:
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12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 19
Protection Board Installed And Wired. 3CX6000A7 12KW CCS 160-15 Meter Linear Amplifier Here the modified protection board is installed, along with the vac relays, cutoff bias resistors etc. The series bias diodes will be installed next....along with the plate choke etc. https://www.youtube.com/watch?v=33mAWX_N5lw
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AL-1200 input tuning
2
I would like to tweak the input tuning on my AL-1200 to see if I can reduce the VSWR presented to my FTDX101MP. The AL-1200 manual doesn't say anything about this, and doesn't even tell which coil is for which band. I emailed Ameritron about this in 2022 and they told me The bottom coil is 160 and the top is 12/10. I also asked them for the procedure they use to tune the coils during production, but they wouldn't tell me. I asked if I could slide the top cover back just far enough to be able to tune the coils with the amplifier operating, and they said no because of safety concerns. But the amplifier needs to be turned on or there is no way to actuate the input relay to get RF drive to the input circuit. I've been working on tube amps for years and know how to do it safely. Should i just slide the cover back a little or is there a better way to do it on this amp? Thanks! 73, John, K9MM
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Please reply to this message and include an attachment. I don't want to have a discussion here or for this thread to get out of control so please just say hi, attach a picture, and that's it.
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Hi all, I'm in the beginning of planning on replacing the slow mechanical TR switches/relays in my 2K-3. Looking at the schematic it appears pretty straight forward. 12v to each relay. I have three questions about this... 1. Does anyone have an opinion on which vacuum relays to use? 2. How do I sequence them? 3. Ideas on physically mounting them. Any opinions would be appreciated. Thank You very much. Bob W4JFA
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