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Re: 3CPX800A7 testing questions
If the? tube is rated fo? 3.5 kv, it should hipot? ? a lot more than? ?double that.? ?When driven? ?to max out, the RF? voltage in the? PI? / PI-L? will back feed via the plate block cap...and superimpose itself onto the? tube's? B+? ? DC? voltage.? ?Typ the? total? voltage will be a? little bit less than? double the? key down? loaded? B+? value.?
Any good? 3-500Z? will hi pot test to? 12-16 kv.? ?A? 3CX-3000A7? will? easily? hi pot test to? 20 kv.? ? The? 3x10/15/20? all hi pot test easily to 30 kv.?? Once tube is warmed up? for? 20 mins......with NO B+ applied, then check for shorts? etc.? ?That's when u can get cathode to heater shorts or cathode to grid? shorts.? ?Buddy with the? YC-156? amp went through 12 tubes....? just to get 3? good ones.? ?The 9 bad ones all developed? ?shorts..... but only? after the? heater was on for? 5-10 mins.? If u dont? see any shorts? after? 20 mins... ( test one tube at a time).... then do the hi pot test on each individual tube... removed from? socket, on the bench.? ? Let us know what they hi pot to.? ?Typ hi pot test is run up to aprx 5-10 microamps. Jim? ?VE7RF |
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Dentron MLA 2500B
Doug Renwick
I have a beautiful Dentron MLA 2500B Amplifier that I purchased some years
ago but never turned it on and now will never need to use it. A choice I have is to list the entire untested amp or list the amp (for conversion) and 8875 tubes separately. I know there is still a good market for those tubes as I have sold spares last year. Any advice or interest? Shipping from Canada is not inexpensive. Doug "The difference between stupidity and genius is that genius has its limits." Albert Einstein |
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Re: 3CPX800A7 testing questions
Hello 'Selcor',
Wednesday, March 6, 2019 Thanks a lot for the comprehensive reply. The amp uses this transformer, maybe with a doubler or tripler, it's hard to see without some dismantling. What HT should I test with from the Hi-Pot? Best regards, Chris 2E0ILY mailto:chris@... Ssvnh> Ssvnh> Ssvnh> Ssvnh> Ssvnh> Ssvnh> The 3CPX800A7 is essentially the same as the 3CX800A7. The Ssvnh> main difference is that the 3CPX800A7 is pulse rated and has a Ssvnh> higher arc-over rating. Consequently, it can handle higher Ssvnh> plate voltage. The pulse rated tube has an arc over rating of Ssvnh> 7,000 volts so it can handle 3,500 volts on the plate whereas Ssvnh> the standard tube has an arc-over rating of 5,000 volts and is Ssvnh> limited to 2,500 Volts on the plate. Ssvnh> Ssvnh> Unless the tubes have a direct short cold static testing is Ssvnh> not going to do you too much good. The only surefire way to Ssvnh> test a tube is in the circuit it is designed for or in a test Ssvnh> fixture that is designed to supply the proper operating Ssvnh> voltages etc. Quite often a tube that tests good for shorts Ssvnh> and other defects while cold will fail under test when it has Ssvnh> reached the normal operating temperature. Ssvnh> Ssvnh> Unfortunately, if the tubes have any serious defects you might Ssvnh> run the risk of blowing the amp up. Also, if it has been Ssvnh> sitting for an extended period of time it would be a good idea Ssvnh> to bring the amp up very slowly on a Variac. The electrolytic Ssvnh> caps used in many amps do not do well if they are not Ssvnh> reformed on a regular basis. There is no guarantee that the Ssvnh> caps will do well even if brought up slowly, but you have a Ssvnh> much better chance of things not going up in smoke. The Variac Ssvnh> I use has voltage and current meters so that I can monitor what Ssvnh> is going on. If I see an unexpected sharp rise in current I Ssvnh> can stop before something goes boom. Ssvnh> Ssvnh> 73, Ssvnh> Ssvnh> Steve Ssvnh> Ssvnh> From: ham_amplifiers@... Ssvnh> [mailto:ham_amplifiers@...] Ssvnh> Sent: Tuesday, March 05, 2019 4:02 PM Ssvnh> To: ham_amplifiers@... Ssvnh> Subject: [ham_amplifiers] 3CPX800A7 testing questions Ssvnh> Ssvnh> Ssvnh> 05/03/2019 20:55 Ssvnh> I have acquired an NMR linear amp made by AMP UK using two 3CPX800A7 Ssvnh> tubes. It's bought "as seen and untested" Apart from the RF power Ssvnh> meter smashed and a coupling centre insulator missing on one of the Ssvnh> two 1000pF vac variables all LOOKS well. These tubes are hard to find Ssvnh> and expensive so I want to test them first, as best I can. I have the Ssvnh> usual meters and a decent Hi-Pot tester, what's the safest way to Ssvnh> ensure their functionality before powering it up? I don't have the pin Ssvnh> configuration for them, so if anyone has them, or a link to them I Ssvnh> need that info first :) The amp is designed for 400kHz to 1MHz, so I Ssvnh> am toying with using it on MF at some stage. My Eimac Power Grid Tubes Ssvnh> book doesn't give the pin configuration and surprisingly Googling Ssvnh> hasn't found them either. Thanks. Ssvnh> If the tubes are good I have a bargain, if not I have a good source of Ssvnh> some nice bits. |
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Re: 3CPX800A7 testing questions
Hello Alek,
Wow, that's a comprehensive list, thanks Alek, appreciated :) Best regards, Chris 2E0ILY mailto:chris@... APvbch> APvbch> APvbch> APvbch> APvbch> APvbch> The bible for tubes is here. APvbch> APvbch> APvbch> APvbch> 3CX800A7 is listed. APvbch> APvbch> 73, Alek. VK6APK APvbch> APvbch> On 6/03/2019 5:02 AM, Chris Wilson chris@... [ham_amplifiers] APvbch> wrote: >> >> 05/03/2019 20:55 >> >> I have acquired an NMR linear amp made by AMP UK using two 3CPX800A7 >> tubes. It's bought "as seen and untested" Apart from the RF power >> meter smashed and a coupling centre insulator missing on one of the >> two 1000pF vac variables all LOOKS well. These tubes are hard to find >> and expensive so I want to test them first, as best I can. I have the >> usual meters and a decent Hi-Pot tester, what's the safest way to >> ensure their functionality before powering it up? I don't have the pin >> configuration for them, so if anyone has them, or a link to them I >> need that info first :) The amp is designed for 400kHz to 1MHz, so I >> am toying with using it on MF at some stage. My Eimac Power Grid Tubes >> book doesn't give the pin configuration and surprisingly Googling >> hasn't found them either. Thanks. >> >> If the tubes are good I have a bargain, if not I have a good source of >> some nice bits. >> >> APvbch> APvbch> -- APvbch> From sunny Binningup APvbch> APvbch> Family Businesses: APvbch> SP Electrical. www.spelectrical.net.au APvbch> The Velvet Fox. APvbch> Smart Design Electrical. APvbch> APvbch> Perth Interiors. APvbch> APvbch> APvbch> APvbch> |
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Re: 3CPX800A7 testing questions
¿ªÔÆÌåÓýThe 3CPX800A7 is essentially the same as the 3CX800A7.? The main difference is that the 3CPX800A7 is pulse rated and has a higher arc-over rating.? Consequently, it can handle higher plate voltage.? The pulse rated tube has an arc over rating of 7,000 volts so it can handle 3,500 volts on the plate whereas the standard tube has an arc-over rating of 5,000 volts and is limited to 2,500 Volts on the plate. ? Unless the tubes have a direct short cold static testing is not going to do you too much good.? The only surefire way to test a tube is in the circuit it is designed for or in a test fixture that is designed to supply the proper operating? voltages etc.? Quite often a tube that tests good for shorts and other defects while cold will fail under test when it has reached the normal operating temperature. ? Unfortunately, if the tubes have any serious defects you might run the risk of ¡°blowing¡± the amp up.? Also, if it has been sitting for an extended period of time it would be a good idea to bring the amp up very slowly on a Variac. ?The electrolytic caps used in many amps do not do well if they are not ¡°reformed¡± on a regular basis.? There is no guarantee that the caps will do well even if brought up slowly, but you have a much better chance of things not going up in smoke.? The Variac I use has voltage and current meters so that I can monitor what is going on.? If I see an unexpected sharp rise in current I can stop before something goes boom. ? 73, ? Steve ? From: ham_amplifiers@... [mailto:ham_amplifiers@...]
Sent: Tuesday, March 05, 2019 4:02 PM To: ham_amplifiers@... Subject: [ham_amplifiers] 3CPX800A7 testing questions ? ?
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Re: 3CPX800A7 testing questions
Bob Naylor
I don't know how that went here. Sorry guys. Bob ?WE6C From: "Bob Naylor wotbob01@... [ham_amplifiers]" To: "ham_amplifiers@..." Sent: Tuesday, March 5, 2019 3:01 PM Subject: Re: [ham_amplifiers] 3CPX800A7 testing questions
?
Will wanna keep in contact with you for sure. I know all about finally meeting the love of my life, like you did. Too bad for all of us it took so long. That means we all have to make the most of the years we all have left. Take care and say hi to Deena, Bob From: "Chris Wilson chris@... [ham_amplifiers]" To: ham_amplifiers@... Sent: Tuesday, March 5, 2019 1:31 PM Subject: [ham_amplifiers] 3CPX800A7 testing questions
?
05/03/2019 20:55 I have acquired an NMR linear amp made by AMP UK using two 3CPX800A7 tubes. It's bought "as seen and untested" Apart from the RF power meter smashed and a coupling centre insulator missing on one of the two 1000pF vac variables all LOOKS well. These tubes are hard to find and expensive so I want to test them first, as best I can. I have the usual meters and a decent Hi-Pot tester, what's the safest way to ensure their functionality before powering it up? I don't have the pin configuration for them, so if anyone has them, or a link to them I need that info first :) The amp is designed for 400kHz to 1MHz, so I am toying with using it on MF at some stage. My Eimac Power Grid Tubes book doesn't give the pin configuration and surprisingly Googling hasn't found them either. Thanks. If the tubes are good I have a bargain, if not I have a good source of some nice bits. -- Best Regards, Chris Wilson. mailto: chris@...
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Re: 3CPX800A7 testing questions
Bob Naylor
Will wanna keep in contact with you for sure. I know all about finally meeting the love of my life, like you did. Too bad for all of us it took so long. That means we all have to make the most of the years we all have left. Take care and say hi to Deena, Bob From: "Chris Wilson chris@... [ham_amplifiers]" To: ham_amplifiers@... Sent: Tuesday, March 5, 2019 1:31 PM Subject: [ham_amplifiers] 3CPX800A7 testing questions
?
05/03/2019 20:55 I have acquired an NMR linear amp made by AMP UK using two 3CPX800A7 tubes. It's bought "as seen and untested" Apart from the RF power meter smashed and a coupling centre insulator missing on one of the two 1000pF vac variables all LOOKS well. These tubes are hard to find and expensive so I want to test them first, as best I can. I have the usual meters and a decent Hi-Pot tester, what's the safest way to ensure their functionality before powering it up? I don't have the pin configuration for them, so if anyone has them, or a link to them I need that info first :) The amp is designed for 400kHz to 1MHz, so I am toying with using it on MF at some stage. My Eimac Power Grid Tubes book doesn't give the pin configuration and surprisingly Googling hasn't found them either. Thanks. If the tubes are good I have a bargain, if not I have a good source of some nice bits. -- Best Regards, Chris Wilson. mailto: chris@... |
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Re: 3CPX800A7 testing questions
The bible for tubes is here.
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3CX800A7 is listed. 73, Alek. VK6APK On 6/03/2019 5:02 AM, Chris Wilson chris@... [ham_amplifiers] wrote:
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From sunny Binningup Family Businesses: SP Electrical. www.spelectrical.net.au The Velvet Fox. Smart Design Electrical. Perth Interiors. |
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3CPX800A7 testing questions
05/03/2019 20:55
I have acquired an NMR linear amp made by AMP UK using two 3CPX800A7 tubes. It's bought "as seen and untested" Apart from the RF power meter smashed and a coupling centre insulator missing on one of the two 1000pF vac variables all LOOKS well. These tubes are hard to find and expensive so I want to test them first, as best I can. I have the usual meters and a decent Hi-Pot tester, what's the safest way to ensure their functionality before powering it up? I don't have the pin configuration for them, so if anyone has them, or a link to them I need that info first :) The amp is designed for 400kHz to 1MHz, so I am toying with using it on MF at some stage. My Eimac Power Grid Tubes book doesn't give the pin configuration and surprisingly Googling hasn't found them either. Thanks. If the tubes are good I have a bargain, if not I have a good source of some nice bits. -- Best Regards, Chris Wilson. mailto: chris@... |
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Latest version of C - L - C ... B+ supply
For the lower voltage? ?5490? (under load)? ?B+? supply? for the 3x3 tube,? I re-configured the myriad of? 10,000uf? filter caps.? This also includes the 78 vdc? vdrop, with the? 1.5 A? flowing through the 52 ohm glitch resistor.? It's? still a C - L - C? config,? but it's now? 625 uf -? ?4H choke -? ?1250 uf .? 16 x 10,000 uf caps in series? = 625 uf.? ?So? 3 x 16 =? 48 caps used in total.? 16 caps? b4 the choke..and? 32 caps? used after the choke.? ( 2 x strings of? 16 each, after the choke).? With a 1.5 A? CCS load,? peak to peak ripple at 120 hz =? ?just? 4.3 millivolts. Rms? ripple =? 1.52? millivolts.? =? -131 db? ?ripple redux? @? 120 hz.? The harmonics at? 240 / 360 480? etc, are way below? -131 db..off the chart.? ?It's all gross overkill? anyway.? ?(? it's? -69 db, with the choke shorted, and just the 1875 uf of filter cap) -? adjustable spark gap? across the choke, set for <100 volts.? -? Kilovac? spst,? 25 kv rated, 65A CCS rated vac relay? wired across the choke.? ?Choke can be shorted out at any time with the flip of a switch.? -? with the choke in the circuit, on paper, it appears it takes? 1.5 seconds for the B+? to drop to it's lowest value,? going from 150ma on idle...to? 1.5 Amps max loaded current.? Dead xcr applied.? On? ssb,? it appears to be longer at 1.7 secs.? 16 x 450 vdc =? 7200.? ? ?5777? /? 7200 =? 80%? ? ? 5777 /16 =? ?361 vdc per cap, well? within their 450 vdc ratings.? For the higher? 7700 vdc B+? ?( for the 3x6 /? YC-243).... the? caps are arranged in 2 x groups of? 25....with a? 400 uf? - 4H choke? -? 400 uf? ?CLC config.? ?Again the choke can be shorted out with the flip of a switch. It's all? academic anyway.? ?No? HV connectors used, it's all hard wired with? 213-U.? Jim? ? VE7RF |
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More PSUD-3 updates coming !
Duncan Monro... who is a ham, who wrote the infamous PSUD-2? ?power supply program,? is also going to add a bunch more features to the? upcoming PSUD-3? version.? ?Data? for the? PRIMARY? side of the plate xfmr will now be included,? like the typ....? ?" Min /? MAX / DIFF /? MEAN? /? RMS"? ?format.? That? format is now used for every parameter of a power supply... for both current..and also? voltage.? I had asked him yesterday to include the xfmr primary data.? ? He just replied a hr ago..and said it would be a simple matter to include it? on? PSUD-3.? ?The idea here of course is, if folks had any clue as to the peak current being drawn every? 8.3 msecs, on the? primary, they will now....a real eye opener.? ?Which then results in? V drops across? mains? wiring / breakers / fuses /? contactors / relays / internal wiring , and all the way back out to the sub panel / main panel,? wiring in between / aluminum drop line? from the street, etc, etc.? Another item I have asked him to add / include,? is to express the? 120 hz? ?ripple as .... ' XX DB down'.? ? Which is how it is done commercially...and is a lot easier to relate to / intuative.? IE:? ?P-P? ripple by itself does not mean much to folks.? ?You have to? divide it by 2.828? to? get? RMS ripple.? Then? you have to? use.....? ? 100 x ( rms ripple? /? loaded B+).? to arrive at? %? RMS ripple.... which folks? still cant? really relate to.?? DB down is? simply? ? ?20 X? log ( rms ripple / loaded B+)? ?Dead simple. EG: on my drake L4B, with? 800 ma loaded? at? 2500 vdc,? ?120 hz ripple is? aprx? -31 db.? ?? IF filter C is doubled, the ripple? ?is now? -37db.?? What's? not on PSUD-2 is? ?ripple /? db down for any of the harmonics....which are of course,? way down in level from the? 120 hz? fundamental? ripple.? ?For glass? audio folks, tube audio amp? guru's? etc, the harmonics? will be at? 240/360/480/600/720 hz? etc.... well within the audible pass band.?? Any other ideas? for improvements to? PSUD, lemme? know asap.? Jim? ?VE7RF |
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Re: 'Toll free' gets blasted with 6 kv !
Same here !
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The snakes were good selling when new... out of sight now. Nowadays, a 9 in the pocket... better than nothing ?? I wonder. Don W4DNR Quoting "'Roger (K8RI)' k8ri@... [ham_amplifiers]" <ham_amplifiers@...>: Sold the Pythons in the 70s. Went through a lot of ammo, but one as clean as I kept those, buying one now |
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Re: 'Toll free' gets blasted with 6 kv !
Looks familiar.? I think it was on/in one of those Stainless Steel Delorians:-D Ran on garbage. Neither sold very well.
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That goes in the category (wish I had done differently) with my 2 Colt Pythons. Good to have in a collection. Sold the Pythons in the 70s. Went through a lot of ammo, but one as clean as I kept those, buying one now would probably cost more than both of those new. 73, Roger (K8RI) On 1/15/2019 2:08 PM, 'Scott, KB3JQQ' kb3jqq@... [ham_amplifiers] wrote:
Another item for your perusal --
Roger (K8RI) |
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Re: 'Toll free' gets blasted with 6 kv !
Awesome!
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-----Original Message----- From: 'Scott, KB3JQQ' kb3jqq@... [ham_amplifiers] To: ham_amplifiers@... Sent: Tue, Jan 15, 2019 11:16 am Subject: Re: [ham_amplifiers] 'Toll free' gets blasted with 6 kv !
?
Another item for your perusal
From: "jim.thom@... [ham_amplifiers]" To: ham_amplifiers@... Sent: Tuesday, January 15, 2019 2:04 PM Subject: Re: [ham_amplifiers] 'Toll free' gets blasted with 6 kv ! "whirly gig atom-smasher thingy".? ? ? ? ?That just cracks me right up.? ?Sounds like a great title for a project...for? 73 magazine.? Ever seen those industrial labels, typ on a blue / black back ground, with etched? white letters.? ? ?"whirly gig atom smasher thingy"? complete with skull? + crossbones seems? fitting.? ? Then an? AC/DC? logo on the back end.?
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Re: 'Toll free' gets blasted with 6 kv !
Another item for your perusal From: "jim.thom@... [ham_amplifiers]" To: ham_amplifiers@... Sent: Tuesday, January 15, 2019 2:04 PM Subject: Re: [ham_amplifiers] 'Toll free' gets blasted with 6 kv ! "whirly gig atom-smasher thingy".? ? ? ? ?That just cracks me right up.? ?Sounds like a great title for a project...for? 73 magazine.? Ever seen those industrial labels, typ on a blue / black back ground, with etched? white letters.? ? ?"whirly gig atom smasher thingy"? complete with skull? + crossbones seems? fitting.? ? Then an? AC/DC? logo on the back end.? |
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Re: 'Toll free' gets blasted with 6 kv !
"whirly gig atom-smasher thingy".? ? ? ? ?That just cracks me right up.? ?Sounds like a great title for a project...for? 73 magazine.? Ever seen those industrial labels, typ on a blue / black back ground, with etched? white letters.?
? ?"whirly gig atom smasher thingy"? complete with skull? + crossbones seems? fitting.? ? Then an? AC/DC? logo on the back end.? ? This is the female chassis HV connector.?? ? Mating male plug? for above...used with? RG-213 U.? ? They rate the above? male / female? ?+? 213-U? at? 25 kv? @ 20A? CCS.? ? ( 28 kv test).? ? Sea level rated.? They are a bayonet type arrangement.? ?There is a ton of different versions of the above.... like? for airborne use, etc,? high altitudes,? different? insulation tricks are used.? ?They are no doubt stupid expensive.?? Buddy's? Hippotronics? 0-30 kv? hi-pot tester uses? RG-59? for internal leads to? front panel posts.? 0 microamps leakage? ?with 30 kv..and nothing connected to front panel posts.? ?So have no clue what? RG-59 really high pot tests to.? And if? 213 -U is used with? 25 kv rated connectors..... we can probably assume that 213 by itself....sans connectors is? gonna? ?hi pot test? a helluva lot more than? 59-U.? ? The above company that makes those 25 kv connectors? sez to? ?use a connector / cable? setup that is rated for ?a? full? 25%? more than what you intend to apply to the assy.? On another note, I can't find any listings? for? SHV? connectors that are rated higher than? 5 kv? @? 3A.? ?There may well be a version out there, but I have not found it yet.? The 10 kv rating is the test rating, not the working rating.? I worked it out how? the 3 x cabs will be wired with 213 U...and no connectors used anywhere.? ? ?RG-59? would also suffice,? but I like the idea of a more robust? stranded center conductor..and a bigger clamping setup for the .405"? OD? of 213. .? I have no clue what the foam versions of coax hi -pot test to.? ? ?The solid poly? types like 213 U appear to be the highest..higher than? foam versions.? Re Bob, DD, last I heard, he was tossed into the slammer..but that was a few years back.?? Jim? VE7RF |
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Re: 'Toll free' gets blasted with 6 kv !
My Harris FM20K has high voltage wire encased in steel flex tube.? Impossible to get smacked with it.?
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John Lyles is the real deal.? He's also one HELL of a nice guy.? I'm on a couple lists he frequents. Anything he says, you can take to the bank.? The SHV 'test' to 10 kv.? I rarely use above 6kv....? Although I've built a couple amps with 12 kv on them.? After about 6kv things get very interesting.? Hi voltage really finds ways to jump, arc, spit, etc.? All my Millen connectors are on micarta, pvc, teflon (cutting board pieces) , etc.? I don't mount them to metal, as Jim stated.....? They will arc if you don't use nylon or other non conductive material as your screws.? I wack a 2 inch hole, install a piece of micarta over it, and used to install the Millen in the center.....? The amp that got me had a piece of 10kv rated wire between the amp and power supply.? The insulation became abraded at the point where the Millen and the insulation met....? This gave a point of pretty much ZERO insulation with 6.2 plus kv.? Hand is healing nicely.? The leg.....? It's still an open sore, but definitely healing up.? Walked out to the shop today, fired up the soldering iron and built a vhf ground plane.? That Fing amp is still sitting next to the bench.? --Shane? KD6VXI? On Saturday, January 12, 2019, jim.thom@... [ham_amplifiers] <ham_amplifiers@...> wrote:
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Re: 'Toll free' gets blasted with 6 kv !
<Randy Jan 11 7:32 PM <Another reply from the same guy; obviously the pic isn't attached, but I can post it to the files if you <reallllllly need it. <Here's a photo of a 25 KW FM tube PA transmitter with the external power supply in the white cabinet on <the left. It runs 9500 volts from that to the big blue and black cabinet on the right which is the transmitter <itself. <RV ##? does it show the HV cabling between em ?? ?Post em anyways. Those pix are awe inspiring.? Ok, so when? you local RI shows up one day and asks.. 'what the hell are you up to'?? ? ?Just tell em you are working on a prototype..'atom smasher'.? Jim? VE7RF |
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Re: 'Toll free' gets blasted with 6 kv !
Glad to hear you are still kicking. That makes my foray into getting poked with 408 AC and 540 DC as mere tickles although after the 540 I woke up on the basement floor. I had been working up on the desk.? Never trusted VTVMs with steel handles after that and power supplies where the current was measured across a resistor in line. Voltage was proportional to the plate current.
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73, Roger (K8RI) On 1/4/2019 12:33 PM, Toll Free TollFree1800@... [ham_amplifiers] wrote:
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Roger (K8RI) |
Scott, KB3JQQ