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FYI: "WARNING: Never mix ammonia with bleach. This causes the release of toxic chlorine gas, which can be deadly." Read ingredients of the products you are mixing. If they have the above in any amount don't mix. Dale, K9VUJ

A local ham dropped in a Yaesu FL-2100Z amp tp me and said that he would like all the PA0FRI mods done to it. See http://www.pa0fri.com/ This is no big problem, as most of the mods are common sense and they are what one would normally do to an amp. However, there is one mod that strikes me as odd. He suggests cutting the grounding wires on VC1, the plate tune capacitor, and running a thick wire or coax from the cold side of VC1 to a ground point at the base of one of the 572B sockets. This seems very odd to me. I don't see how this would enhance stability, having that grounding wire running all that way. Every amp I have seen or built, has the cold end of the capacitor bonded to the nearest point on the chassis. Should one be doing this mod? My feeling is that it should be left alone. Opinions appreciated. Thanks, Alek. VK6APK -- From sunny Binningup Family Businesses: SP Electrical. www.spelectrical.net.au The Velvet Fox. https://www.facebook.com/TheVelvetFox/ Smart Design Electrical. https://www.facebook.com/smartdesignelectrical/ Perth Interiors. https://www.instagram.com/perthinteriors/

HI all, Thanks for reading the mail. I have acquired a home brew amp and power supply that is missing its HV cable. I'd like to change both of them to one style since they are both different. Jack Schutt K9GT originally built this. I'd thought about using SO-239/PL-259's that are Teflon with RG-8 inner conductor cable as the HV wire and packing the PL-259's with RTV-108 and sleeving the wire with GOOD Belden heavy shrink tube with sealant. Does that sound like it would hold 5 KV since that's what Jack built the power supply too? Thanks for the input and reading the mail. Kim Herron W8ZV w8zv@... www.goldenradioservice.com 616-677-3706

All- I have an Amp Supply Company LK800A amplifier that puts out full power. However, I noticed recently that it shows no grid current reading when transmitting on multiple bands. This is odd behavior, as the grid current normally runs ca. 20-50 mA from my past experience. I know the meter is fine, because when I turn the meter switch to measure plate voltage, I get the expected reading. I looked at the meter/ALO board and found that R29 was somewhat charred and had a reading of 180 K ohms. No other parts look visibly damaged. The LK-800 series manual does not have a schematic for this board. I was able to find one at http://www.radiomanual.info/schemi/ACC_PA/Amp_Supply_LK-400_LK-500_series_user_1988.pdf. While the manual is for the LK-400 / LK-500 series, it does have a description of the ALO/Meter board. The resistor R29 is in the grid current metering circuit and is claimed to have a value of 18 ohms (p. 27 and 29). I suspect this is the problem. The other parts on my board seem to match what is listed on p. 29, and the parts list on p. 29 suggests the board works in the LK-800 series amps because it references the heavy resistor R30 as being unique to the LK-800 (and is present on my board). My question - can someone verify that R29 should indeed be 18 ohms? I would hate for there to be a misprint in the manual and find my grid current meter to be blown when I try this out, as I suspect they are very difficult to obtain. Also, do you have any insights as to what would blow this resistor? A current of 120 mA through that resistor would deliver 0.25 watts... I have always kept the grid current low, but I did loan the amplifier out a few years ago and don't know if the other user experienced an issue. Many thanks, -Mark

12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 21 125 uf @ 9kv dc Capacitor Bank for the 7.5 kv B+ supply for the 160-15m 3CX-6000A7 PA. Each cap is 9.8 Amp CCS Ripple Current rated @ 120 hz. .041 ohm per cap ESR...also @ 120 hz. Here the 20 x 2500uf @ 450 vdc caps are mounted....and will be wired in series. These are 95C rated units, made by CDE. Each cap will get a 100K @ 3 watt MOF across it. The entire assy will drop into the base of the cabinet. https://www.youtube.com/watch?v=kMY8q7vJ3Yg

The following items have been added to the Files area of the [email protected] group. /Peter Dahl catalog.pdf By: Jim VE7RF <jim.thom@...> Description: Peter Dahl catalog

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

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

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

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

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

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