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Re: RG-213 Hi pot ?
Excellent!? That is exactly what I have used for decades when trying to move extremely angry electrical pixies from one place to another.? Sometimes, I have run the 440 through Teflon? tubing before inserting the whole assembly into the braid.
Packard 440 is, by itself, usually sufficient; but, when routed through another layer of insulation, especially when protected by grounded braid from coaxial cable, it is safe for toddlers to play with while doing its job (Not a recommendation!).
Ed. KI6DCB
Although the author has received many significant electrical shocks and burns, among which were several from potentials greater than 30 kV and a few others from RF sources [much] greater than 1 kW PEP, some of which required medical attention, these events have not impaired his ability to have opinions about many things, especially the care and feeding of high-voltage/high-current electrical power sources.? Furthermore, no toddlers were injured in gaining the knowledge and experience required to have this opinion, although many smaller things -- most notably, various insects, bugs, small rodents, several screwdrivers, three or four voltmeters, and one oscilloscope -- have made the ultimate sacrifice in the furtherance of the author's knowledge and experience.? It must be noted that everyone's constellation of experiences is different from that of every other person, and that the author's experiences may not be applicable in any or every other situation.? Your experiences may be substantially different from those of the author of this post. -----Original Message-----
From: donroden@... [ham_amplifiers] To: jim.thom@... [ham_amplifiers] Sent: Fri, May 10, 2019 10:14 am Subject: Re: [ham_amplifiers] RG-213 Hi pot ?
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I'm using neon sign HV wire on a 10,000 volt 30KW FM transmitter
( Inside a run of metallic conduit ) Packard 440 ignition cable is tinned / stranded from Auto Parts stores... you could run it inside a braid stripped from RG8 or RG 58. Don W4DNR Quoting "jim.thom@... [ham_amplifiers]" : > Does anybody know how much max V is on RG-213 ? Like what are the > results if a hi-pot tester used..and say cranked up to the point > where just a few microamps occurs . I have an application where > I need a HV cable, less than 10 ft, that will easily handle 5700 / > 7700 vdc. It will be hardwired at both ends, no HV connectors. > And with braid peeled way back from the center conductor, like 2-4 inches . > The plan was to also wrap some red electrical tape every few > inches along its entire length, to readily identify it as a HV > cable. > > > I have loads of RG-393, but don't want to waste it for this application. > > Tnx.... JIm VE7RF |
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Re: 6 Meters Parasitic for 3-500Z
If? you use? GM3SEK's? ?pi? spreadsheet,? ?you will have some wiggle room.? The trick is to insert a tiny bit
of uh... between plate block cap and C1 main tune cap.? ?The combined tube C? from both tubes? ( anode? to chassis).....? +? that extra? tiny? uh? between? plate block caps..and? C1? tune cap..... will then form a step down? L network.? ? IE:? it will step down the plate load Z..way down.... to a lower value.? ?Then? the PI net will? easily match the lower value.... down to? 50 ohms.? ?Then you won't end up with a sky high loaded? Q.? To pull this off,? you need to measure the pf? ?between either anode..and chassis..... with both tubes plugged into sockets..... and also with all 6 x grid pins? bonded to chassis.? ?Knowing that info..it's then? plugged into the spreadsheet? ?as? ? "stray pf? between anode and chassis".? ? Enter calculated plate load Z... and let it spit out results.? ?You may? well have to increase the loaded Q? on the spreadsheet? to get a C1? value? that your tune cap can handle.? ? ?Then start inserting a tiny bit of? uh,? like? .1 uh....? in the stray uh column for the spreadsheet.? ? It will then spit out the lowered plate load Z the PI net is now trying to match.? ?At that point,? you should also be able to also lower the Q? in the spreadsheet.? Then? try a tiny bit more? uh before the C1 cap.... like say .15 uh..or? even? .17 uh.? ? You want to insert just enough? uh? ?to do the job, and no more.? ?That extra uh? should be made of? strap material...and ditto with the main? 6m? coil? ( between? tune and load cap).?? Same trick is used on the YC-156? to get it to work on 6M....? dues to the c 50 pf? ?between? anode and chassis.? ?YC-156? is? 35 pf as is.... on a wooden bench..... but rises to 50 pf...when bolted to chassis.? The extra 15 pf comes from the proximity of the lower anode fins to the chassis below the fins.? later.... Jim? ?VE7RF? |
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Re: RG-213 Hi pot ?
I'm using neon sign HV wire on a 10,000 volt 30KW FM transmitter
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( Inside a run of metallic conduit ) Packard 440 ignition cable is tinned / stranded from Auto Parts stores... you could run it inside a braid stripped from RG8 or RG 58. Don W4DNR Quoting "jim.thom@... [ham_amplifiers]" <ham_amplifiers@...>: Does anybody know how much max V is on RG-213 ? Like what are the results if a hi-pot tester used..and say cranked up to the point where just a few microamps occurs . I have an application where I need a HV cable, less than 10 ft, that will easily handle 5700 / 7700 vdc. It will be hardwired at both ends, no HV connectors. |
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RG-213 Hi pot ?
Does anybody know how much max V is on? RG-213 ??? Like what are the
results if a hi-pot tester used..and say cranked up to the point where? just a few microamps occurs .???? I have an
application where I need a? HV?cable, less than 10 ft, that will? easily handle 5700 /? 7700? vdc.?? It
will be hardwired at both ends, no HV connectors.
And with braid peeled way back from the center conductor, like? 2-4 inches
.?
The plan was to also wrap some red electrical tape? every few inches? along
its? entire? length, to readily identify it as a HV cable. I have loads of? RG-393, but don't? want to waste it for this application.? ?
?
Tnx....? JIm?? VE7RF |
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Re: 6 Meters Parasitic for 3-500Z
Hello Jim,
Thank for your feedback. Yep resting current is on higher side Eimac recommand 58 mA per tube so your dead on. I finally finding a good combinaison of resistor-L.? The commercial unit was having a big parasitic using 60W non inductive 50 Ohms resistor on each tube..so i reuse it but put a nice wide strap to replace the coil form and it is working 100% now. I ending showing up 1kw with 58 W of drive.? Yes i know it can be more efficient? I play with 2 different L in the pi-network to lower Q but each time i hit the limit of the low value of my 3-30 Pf...stray C was the limit.? So i addend inductance in the Pi-network still it is manageable with the TUNE cap.? The Q was probably in the 20 value but complete redesign of the component placement was the solution i think for better efficiency. HV was 3kv full load. Jim nice to read you as usual and will talk to you soon about the YC156 sitting here and waiting for the 6 meters amp to get out the shop :) 73 Guillaume |
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Re: 6 Meters Parasitic for 3-500Z
##? with? 150ma +? 3500 vdc, idle power =? 525 watts.??
##? I would reduce the idle? current down to? 100 ma.? ............................................................................................................................................................................ ##? The trick is...to? reduce the size of your loop just a TINY bit.? ?IF you reduce it too much, it will go into osc.? ?IF it's too big, then you couple too much power into the pair of resistors.?? ##? Ideally you want...JUST enough loop to suppress the osc, and no more.? It's a delicate balancing act..esp on 6m.? ##? ?5 x 250 ohm, 3 watt MOF's? would result in the same 50 ohms, albeit a lot more power handling capability. MOF's? are not? pure resistive either, they have some built in stray XL to them.? ?I believe KM1H's? fix for that was to? cancel out the XL? with a series? cap.....one cap per resistor.? ?Or 4 x 200 ohm MOF's? with caps. ##? Ideal resistor? would be a? 10-15-20 watt? /? ?50 ohm globar.? ?Carbon comp resistors would also work, then no compensating caps? required.? ? ?Like 4 x 200 ohm CC, or? 5 x 250 ohm CC.? I assume you have the? 3 x grid pins bonded to chassis with strap...per tube ?? Jim? ?VE7RF ?? ? ---In ham_amplifiers@..., <va2na@...> wrote : Hi amp builder, I just finishing a 6 meters amp using a pair of 3-500Z on old Marconi BH-30 case. Everything is working as it should but i can't find the right parasitic supressor setup. I am using large copper loop with 2 X 100 ohms 2W Metal oxide resistor for the last design and at 500W resistor get pretty hot quickly. I try much smaller loop but ending having the amp goes in oscillation as soon as i apply bias hihihi. Amp is running 3500V on the plate and having 150 mA of resting current. Right now? with 17-20W in getting 500W out so it feel very healthy.. i only need to address this parasitic and I will be ready, Need your input here...? if you mention W8ji site and other reference i already take a bunch of reading... Best 73 Guillaume |
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6 Meters Parasitic for 3-500Z
Hi amp builder, I just finishing a 6 meters amp using a pair of 3-500Z on old Marconi BH-30 case. Everything is working as it should but i can't find the right parasitic supressor setup. I am using large copper loop with 2 X 100 ohms 2W Metal oxide resistor for the last design and at 500W resistor get pretty hot quickly. I try much smaller loop but ending having the amp goes in oscillation as soon as i apply bias hihihi. Amp is running 3500V on the plate and having 150 mA of resting current. Right now? with 17-20W in getting 500W out so it feel very healthy.. i only need to adress this parasitic and i will be ready, Need your input here...? if you mention W8ji site and other reference i already take a bunch of reading... Best 73 Guillaume |
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Re: Henry 2k4A problem
¿ªÔÆÌåÓýRF parts replaced the tube. The owner had the optional warranty.? Its back up and running great. C On 4/25/2019 5:26 AM, Alek Petkovic
vk6apk@... [ham_amplifiers] wrote:
? -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 |
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Re: Henry 2k4A problem
Compare it with a known good tube, idle current and PO should be within 20% or so.
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Otherwise use it in a single tube amp until it dies of old age. Carl ----- Original Message -----
From: Alek Petkovic vk6apk@... [ham_amplifiers] To: ham_amplifiers@... Sent: Thursday, April 25, 2019 8:26 AM Subject: Re: [ham_amplifiers] Henry 2k4A problem On 25/04/2019 8:03 PM, jim.thom@... [ham_amplifiers] wrote: <Yeah, I have done that with a 3-500Z which showed a short. I stuck the <shorted element pins across the 12V battery in my car. <It certainly cleared the short and I have kept the tube but I'm too <chicken to plug it in to the amp. :-) <I guess that's a bit silly, as there is surely not a great deal that can <go wrong but it would be nice to hear of other people's success or <failure, before hitting the on switch, in the home brew amp. <73, Alek ## Applying 12 vdc between grid and cathode will usually do one of 2 things. 1) weld it shut. 2) blow it wide open A 12 vdc car battery has enough current capability to do either of the above. Jim VE7RF Yep. It blew it wide open, which I verified with the Ohmmeter and 1000V Megger. The thing I do not know, is how much, if any, of the grid is left intact, inside the valve. Hence the reluctance, to date, to try it in an amplifier. :-) Cheers, Alek. VK6APK -- From sunny Binningup Family Businesses: SP Electrical. www.spelectrical.net.au The Velvet Fox. Smart Design Electrical. Perth Interiors. --- This email has been checked for viruses by AVG. |
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Re: Henry 2k4A problem
¿ªÔÆÌåÓýOn 25/04/2019 8:03 PM, jim.thom@... [ham_amplifiers] wrote:
Yep. It blew it wide open, which I verified with the Ohmmeter and 1000V Megger. The thing I do not know, is how much, if any, of the grid is left intact, inside the valve. Hence the reluctance, to date, to try it in an amplifier. :-) Cheers, Alek. VK6APK -- From sunny Binningup Family Businesses: SP Electrical. The Velvet Fox. Smart Design Electrical. Perth Interiors. |
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Re: Henry 2k4A problem
<Yeah, I have done that with a 3-500Z which showed a short. I stuck the?
<shorted element pins across the 12V battery in my car. <It certainly cleared the short and I have kept the tube but I'm too? <chicken to plug it in to the amp. :-) <I guess that's a bit silly, as there is surely not a great deal that can? <go wrong but it would be nice to hear of other people's success or? <failure, before hitting the on switch, in the home brew amp. <73, Alek ##? Applying 12? vdc? between? grid and cathode? will? usually do one of 2 things. 1)? weld it shut. 2) blow it wide open A? 12 vdc? car battery has enough current capability to do either? of the above.? Jim? ?VE7RF? |
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Re: Henry 2k4A problem
Yeah, I have done that with a 3-500Z which showed a short. I stuck the shorted element pins across the 12V battery in my car.
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It certainly cleared the short and I have kept the tube but I'm too chicken to plug it in to the amp. :-) I guess that's a bit silly, as there is surely not a great deal that can go wrong but it would be nice to hear of other people's success or failure, before hitting the on switch, in the home brew amp. 73, Alek On 17/04/2019 11:08 PM, 'Carl' km1h@... [ham_amplifiers] wrote:
You might be able to blow the short out with a bit of voltage. --
From sunny Binningup Family Businesses: SP Electrical. www.spelectrical.net.au The Velvet Fox. Smart Design Electrical. Perth Interiors. |
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Re: Henry 2k4A problem
You might be able to blow the short out with a bit of voltage.
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Using a variac or a seperate supply, AC or DC, instantaneously apply the voltage; I do it with the tube on the bench, a pair of clip leads and just brush one against a pin and see a momentary spark or meter jump. Start at some low voltage like 10V and increase as needed. No guarantee but Ive been about 50% successful over the decades with Eimac and import tubes. Carl ----- Original Message -----
From: Clark Turner clark@... [ham_amplifiers] To: ham_amplifiers@... Sent: Tuesday, April 16, 2019 3:03 PM Subject: Re: [ham_amplifiers] Henry 2k4A problem Swapped the right tube out and the condition is gone. Looks like a problem in cold start with grid short. C On 4/16/2019 9:04 AM, Clark Turner clark@... [ham_amplifiers] wrote: That is not possible on this brand of amplifier. The filament are in series. C On 4/15/2019 6:28 PM, Alek Petkovic vk6apk@... [ham_amplifiers] wrote: Pull the tubes and turn on from cold. If all ok, insert one tube at a time and retest. If it is a temporary short, as you suggest, then it will surely show itself and you can determine which tube is dodgy. Cheers, Alek. VK6APK PS: Murphy says that the action of pulling the tube and reinserting it, will be sufficient to remove the cold short and you'll never find which tube it was in. Ha ha. On 16/04/2019 6:33 AM, Clark Turner clark@... [ham_amplifiers] wrote: A friend has a 2k4A amp with two 3-500Z tubes(RF parts). It has an odd-- From sunny Binningup Family Businesses: SP Electrical. www.spelectrical.net.au The Velvet Fox. Smart Design Electrical. Perth Interiors. -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 --- This email has been checked for viruses by AVG. |
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Re: Henry 2k4A problem
¿ªÔÆÌåÓýSwapped the right tube out and the condition is gone.? Looks like
a problem in cold start with grid short.? C On 4/16/2019 9:04 AM, Clark Turner
clark@... [ham_amplifiers] wrote:
? -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 |
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Re: Henry 2k4A problem
¿ªÔÆÌåÓýThat is not possible on this brand of amplifier. The filament are
in series.? C On 4/15/2019 6:28 PM, Alek Petkovic
vk6apk@... [ham_amplifiers] wrote:
? -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 |
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Re: Henry 2k4A problem
¿ªÔÆÌåÓýThank you for the reply.? Its sad because the amp will run all
night once the short is cleared.? We will swap out a spare tube
one at a time to find which tube. C On 4/16/2019 2:01 AM,
jim.thom@... [ham_amplifiers] wrote:
? -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 |
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Re: Henry 2k4A problem
<Pull the tubes and turn on from cold. If all ok, insert one tube at a? <time and retest. If it is a temporary short, as you suggest, then it? <will surely show itself and you can determine which tube is dodgy. <Cheers, Alek. <VK6APK ##? Grid? current meter? pegged? backwards...while showing plate current is usually indicative of a grid to cathode short on one of the two? tubes.? ?IF? I remember correctly,? Henry wires the directly heated cathodes in SERIES,? and uses a 10 volt @ 15A? fil xfmr.... same as the? TL-922.? ?The problem with that setup of course is...... when one? tube is removed, the other tube? won't light up !?? ##? To get one tube? to light up,? u require a temp short across the cathode of the 2nd tube.... which won't work, cuz then? you have the full 10 volts? across the remaining tube..which will fry it asap.? ##? whats? needed is? either a single tube test fixture ( or a single tube amp like an? AL-80B)? and a? 5 v? fil xfmr.... or a 2? tube amp like a SB-220 /? L4B...with? both tubes removed, then? insert? each tube from the Henry amp...one at a time, into the test fixture. ##? watch out with using a 5V? @? 30A? fil xmfr on just a single tube...and no fil xfmr step start circuit.? ?W7IUV? fried several? ?single? 4-400's? that way.? ? Cold resistance is just? 1/10th the hot resistance..and with a 30A? fil xmfr being used....will? ?fry the single tube's cathode.? ?This is where a small variac comes in handy when testing flaky tubes.? ##? about the only advantage of running 2 x tubes? in series is the? bifilar can be sized for? 1/2 the current...? IE:? 15A? /? 14 gauge wire..... vs? ?30A? /? 10 gauge wire.? ?Which really isn't worth it when one tube starts to go bad. Jim? VE7RF? ? |
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Re: Henry 2k4A problem
Pull the tubes and turn on from cold. If all ok, insert one tube at a time and retest. If it is a temporary short, as you suggest, then it will surely show itself and you can determine which tube is dodgy.
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Show quoted text
Cheers, Alek. VK6APK PS: Murphy says that the action of pulling the tube and reinserting it, will be sufficient to remove the cold short and you'll never find which tube it was in. Ha ha. On 16/04/2019 6:33 AM, Clark Turner clark@... [ham_amplifiers] wrote:
A friend has a 2k4A amp with two 3-500Z tubes(RF parts). It has an odd --
From sunny Binningup Family Businesses: SP Electrical. www.spelectrical.net.au The Velvet Fox. Smart Design Electrical. Perth Interiors. |
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Henry 2k4A problem
A friend has a 2k4A amp with two 3-500Z tubes(RF parts).? It has an odd problem. When you turn the Amp on, the Grid meter pegs backwards and the plate current shows 200MA.? If you key the mic about 10 times it all of the sudden goes back to 0 grid and 0 plate current as normal.
I have cleaned the relay contacts and am confident they are working I have replaced the Stud mount Zener diode as I had several spares. The amp will run the rest of the night at full power. This condition ONLY happens when you first turn amp on cold. It will never return until amp is off over night and turned back on next day. Possible Grid short on tube that is clearing up after some current is on it?? Any suggestions? C -- Please let me quote you for your parts needs! I offer a discount on Protunes with parts order! Clark Turner 480-695-2898 |