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Re: 'Toll free' gets blasted with 6 kv !
¿ªÔÆÌåÓýI am ashamed to say, I have bitten a couple times by the high voltage in an amp.? Both were from stupidity, but¡one with an explanation! ? Years ago, I built a Heathkit SB220.? Did a super, factory like job (I can solder with the best if ¡®em [Well..used to be able¡palsy now¡.? L] Anywho.? When I fire it up, it didn¡¯t.? WTH!? (Use whatever letter you wish!)? Started by discharging the cap bank, a good deep discharge¡ Then started to probe for voltage loss.? Next thing I remember, I was in the hall, on the floor¡.and I *³ó²¹»å²Ô¡¯³Ù* opened the door.? My right arm was numb and I had a big black spot in my vision. ? Wife came running wanting to know, you guessed it¡¡±WHAT HAPPENED??!!¡±? Not, ¡°Are you ok?¡±? (Remember, I said I was on the floor!}? Women.? SHEESH! ? Long story short, I had made an assumption the cap bank was discharged.? NOT!? For some reason, I had not connected the 2 banks into the amplifier circuit, only 1 bank was connected, but both banks charged.? OOPS!? Luckily (for me) the amp was disconnected from power. ? The 2nd time, well¡.pure and simple stupidity.? A Henry 2KD Classic with a Euro transformer.? Someone had really screwed up the 120/240 wiring and I was trying to finger out which non-colored wire was which.? (Reason I was given the amp, didn¡¯t work.)? Power was on, left hand in my belt, no metal grounds anywhere¡ ? µþ³Ü³Ù¡ ? A VOM with little tiny probes, only 1 inch long with little plastic, nothing handles.? While in a very tight space, my knuckle on my right hand touched a 600 volt line.? HOLY CRAP. Mother of God! J. H. Kerist!? ? Pretty good (sic) burn up my knuckle into the palm of my hand.? Hurt like hell, stunk like a sewer plant, and tears were pouring from my eyes.? This time, the wife did ask me if I was all right.? I think I snapped at her, something like, ¡°Does this look like I am all right?!¡±? She said, ¡°Come dear, let¡¯s get this under some cold water¡±.? (I followed meekly.)? (BTW, my wife of 48 years is a doctor, she know things <> ) ? ? Yes, I am absolutely sure, the ¡®1 hand behind the back¡¯, saved my bacon the 2nd time.? 1st time, no¡? I also now have some nice, top dollar, extra-long, insulated probes for my VOM. ? Oh, the amp works great, with the original tubes still in it, (How old they were I have no idea, amp had the Euro transformer installed in 1989 by Henry¡ªI have the receipt from the repair/modification.? It tunes up to about 1600 watts out.? Never did put new tubes in.? I did try the old tubes in an L-4B and tuned up to 900 watts out, so the humongous high voltage fo the Euro transformer, gave a pretty good boost!? The Henry sits under my radio table, to use in case of an emergency, ie: ?My L7 not working. ? There is my tale of woe (stupidity times 2!) ? {{Did I mention I **hate** high voltage?}} ? Joe ¨C W7RKN ? ? ? From: ham_amplifiers@... [mailto:ham_amplifiers@...] ? One of the *worst* reactions from the old hens here was when I said to always keep one hand in your pocket when dealing with HV.... Which was immediately followed by people that had real-world experience almost being turned into toast by not following that basic rule... |
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Re: 'Toll free' gets blasted with 6 kv !
¿ªÔÆÌåÓýBest wishes to Shane & his family for a speedy recovery. One of the *worst* reactions from the old hens here was when I
said to always keep one hand in your pocket when dealing with
HV.... Which was immediately followed by people that had real-world experience almost being turned into toast by not following that basic rule... FFS, I've got nothing to prove here, not *here* amogst y'all...
although nobody from the hereafter that had a hand on the chassis
when he croaked has checked in to this *(unmoderated) list, and,
presumably, if AG6K was in Hell, he'd have QRMd it by now. Jim... having overthunk the choke thing... methinks that "if" you had 2H in the B+ AND 2H in the B-, THEN the back EMF would equalize.... and, and, well, Hell, what's the point of that? Where ya gonna put the scope leads, the meters... meh... it'd be easier to design a new class of (vacuum-tube) devices to clamp the V... Canadiodes... eh?
73 Randy
On 12/21/2018 8:23 PM,
jim.thom@... [ham_amplifiers] wrote:
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Re: New PSUD-3 now in the works !
? Several emails between me and? Duncan Munro..who is also a ham.? ?All these anomalies are being fixed as we speak.? ?Also, if u do something stupid, like use less than the min inductance for a choke, on a choke input filter, it will let u know asap.
I also asked him to include more stuff, like? express? ripple in db down, which is what's used in the commercial world, which makes more sense? vs? ripple %.? ?Also what? might be included is 3 phase? setups, with 3 x common rectifier configs . Filter ringing will also be addressed.? ? We also need a better stepped load feature, that? depicts a dynamic load better.? ?There is a bunch of more stuff? being looked at.? Stay tuned.? new version will be called? PSUD-3.? But it won't be ready for a while, with all these extra features and other fixes being in the mix.? ?He also has? LTspice, which does depict stuff a bit more accurately..and does stuff like factoring in diode C etc.? ?New version will also include resonating a choke..+ stuff like? RC snubbers across a choke and xfmr sec, etc.? Hams won't use most of this stuff, but the DIY tube audio guys sure do.? ?As is, PSUD is the only thing I have found that will depict rms current into a filter cap...which is? typ? 2.5? X? max plate current.? ? Most of these rinky dink modern day 200 /330 uf caps are only rated for 1.5 to 1.75A? ripple current as is.? ?Which is barely up to the task? for? tube that sucks? 800ma.? ? ? ? ? Jim? VE7RF? |
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Re: 'Toll free' gets blasted with 6 kv !
<Carl Dec 20 3:49 PM < I stopped using those 30-40 years ago even at 2500V < Carl ## OK, I'll? bite.? ?What do you use for hv connectors ???? ##? On a similar note,? buddy with the hipotronics hi pot tester? sez the internal? HV wire? leads? inside the unit? use plane jane? RG-58..to get to the internal panel? positive and negative connectors they use. The unit is? adjustable from 0-15 kv on lower scale....and? 0-30 kv on high scale.? ?At 30 kv... there is zero leakage, none,? zero ua.? ? ?RG-400, with it's? teflon,? ?should be even better than? 58-U.? Heck, even? 213-U should be ok..as long as it's marked every few inches? with red tape? etc.? I have? 200'? of new? 393..so can spare a few feet of it for this latest project..which is a potential? bomb as is..with 800uf? filter cap and? 7700 vdc.? Jim? ?VE7RF? |
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Re: 'Toll free' gets blasted with 6 kv !
I stopped using those 30-40 years ago even at 2500V
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Carl ----- Original Message -----
From: jim.thom@... [ham_amplifiers] To: ham_amplifiers@... Sent: Wednesday, December 19, 2018 10:21 PM Subject: [ham_amplifiers] 'Toll free' gets blasted with 6 kv ! I heard through the grape vine that toll free / aka Shane, / KD6VXI, just about blew his finger off, on a Millen HV connector, with 6 kv on it. Don't ever get near one of those things, when there is B+ on it. Jim VE7RF --- This email has been checked for viruses by AVG. |
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Re: 'Toll free' gets blasted with 6 kv !
Solid-core spark plug wire -- Packard 440 or similar -- is the way to go.? It's extremely durable, reasonably flexible, and good to well over 25 kV.? If you're not comfortable with that, you can easily open up some braided ground strap or strip some coax and run the wire through the [grounded] braid.? With that setup, there's no way that your HV is going to reach out and touch someone.? Unless, of course, you do something stupid and/or careless...
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...Some years ago, I was working on a megawatt-class amplifier.? The driver stage required 6 kV at six Amperes, and there was an issue which required me to disconnect the HV from the driver stage.? The 6 kV supply output was through a maroon, screw-on Millen connector, which was 100% reliable at 6 kV.? I dutifully unscrewed and removed the HV lead from the supply and performed the tests.? When I entered the amplifier to reinstall the lead, everything was fine until the lead got close to the output connector.? The "BANG!" in the enclosed space left me momentarily deaf, and the flash left a black spot in my vision for several minutes.
It turned out that the bleeder string(s) on the 6 kV supply had opened up, leaving about 900 Joules (50 microfarads) to find ground in a few milliseconds.? To this day, I'm very glad that it hit the lead and not my hand; and I always, ALWAYS have used caution -- and chicken sticks -- since that event.
By the way, fixing the bleeder problem solved the issue which started the trouble. Edmund Watts
ed_watts@... -----Original Message-----
From: jim.thom@... [ham_amplifiers] To: ham_amplifiers Sent: Thu, Dec 20, 2018 5:43 am Subject: RE: [ham_amplifiers] 'Toll free' gets blasted with 6 kv !
?
Drake uses em on the back of the L4B? RF deck, but the HV lead? coming out of the loom is like the center conductor + poly off of some 8-U coax? and? it's really short...and max of? 2650 on it..on rx.?
I used the damned things on the hb supply, with 6.7 kv, then sold it to the buddy with the YC-156 amp u see on the pix page.? ?He redid them , this time on the side of the cabs,, and mounted to? some? square? HV? micarta...+ nylon screws.?
When I had it, one day the line V went up to? 247 V..and? B+? rose to a hair under? 7 kv.... and it arced from center to? one of the 2 x SS mounting screws !? ? ?Also, when I got my arm? within 1' of the silicone rubber coated belden 10 kv test prod? wire, all the hair on my arm stood on end, which really? freaked me out.?
Most of
these? HV connectors have one issue or another.? ?Even the Alden ones are not perfect, and are easily pulled out, no locking? provision.? ? The better types use a braid over the dielectric, like? 393 /213? etc, and are configured such that the braid /shield? always makes? contact? 1st..... just b4 the center? conductor? connects.?
On this latest? B+? supply I'm building,? I'm hard wiring all the B+? connections, where the 393 cable goes external? from the HV supply, over to the 2nd cab, which contains the C1 -L-C2? filter, then more? 393 over to the 3rd cab, which contains the RF deck.? Then lugs on the center conductor and braid, strain relief? with a plastic clamp? on a 1" diam stand off, then more strain relief where it exits the cab with those rubber? reducing fittings, that cinch down on the? cabl
e.? ?I'm done with hv connectors,? they all have some kind of? drawback, or are bulky.?
On the inside of the cabs, I used plane jane Belden? 10 kv rated? test prod wire,? 18 gauge, with the silicone rubber insulation...super flexible.? ?Good on the inside of a cab,? but I would not use it external, not robust enough, and silicone rubber is too easily pinched, nicked, etc.? You could slice into it, and the cut slit would self heal, and you would? never know there was a cut into it.?
I have? 200' of 393? coax, with its teflon dielectric over the center conductor and also over the silver plated braid.? ?Then ground the braid at each end.? ?Then a? separate 10 / 8 gauge, insulated wire,? with lugs on each end,? bonding the cabs together.? ?I only need a few? feet for the external? HV wiring.?
<
div>On that YC-156? supply, besides a HV meter in both the HV supply, with its 4 x oil caps etc,? I also had a HV meter in 2nd box, with the? 20 x lytics..and a 3rd? HV meter in the RF deck.? ?IF? HV fuse blows open, the HV meter in the RF deck drops to zero, while the other 2 x hv meters? still reads 6.7 kv.... being on the inboard side of the HV fuse.? ?Also wired 2 x? green neons in series, then wired that mess across the last lytic in the series string, at the cold end.? Works good, and you can see the pair of green? neons? ?from? 50'? away.? ?Good visual? attention getting device.? ?Any box that has HV inside, gets a HV meter.?
Another problem with the millens is there is no provision for strain relief.?
Jim? ?VE7RF?
?? ? ? ? ?
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Re: 'Toll free' gets blasted with 6 kv !
¿ªÔÆÌåÓýYes it is true. I understand he reached around the back of the
amp to deal with some cables and grabbed the B plus line. These
connectors are NOT shielded and neither is the wire.? There is
simply no EXCUSE for this.? TURN THE AMP OFF before working on it
and make sure it has no B plus. I am glad my friend is alive. I
have known him for many years. C On 12/20/2018 9:08 AM, 'Carl'
km1h@... [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: 'Toll free' gets blasted with 6 kv !
Millen rated them to 7 KV
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----- Original Message -----
From: 'Mike Sawyer' w3slk@... [ham_amplifiers] To: ham_amplifiers@... Sent: Thursday, December 20, 2018 5:43 AM Subject: RE: [ham_amplifiers] 'Toll free' gets blasted with 6 kv ! Why would he be crazy enough to do that? Didn¡¯t he know they are only rated for 2~2.5KV????? Mod-U-Lator, Mike(y)/W3SLK From: ham_amplifiers@... [mailto:ham_amplifiers@...] Sent: Wednesday, December 19, 2018 10:21 PM To: ham_amplifiers@... Subject: [ham_amplifiers] 'Toll free' gets blasted with 6 kv ! I heard through the grape vine that toll free / aka Shane, / KD6VXI, just about blew his finger off, on a Millen HV connector, with 6 kv on it. Don't ever get near one of those things, when there is B+ on it. Jim VE7RF --- This email has been checked for viruses by AVG. |
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Re: 'Toll free' gets blasted with 6 kv !
Drake uses em on the back of the L4B? RF deck, but the HV lead? coming out of the loom is like the center conductor + poly off of some 8-U coax? and? it's really short...and max of? 2650 on it..on rx.?
I used the damned things on the hb supply, with 6.7 kv, then sold it to the buddy with the YC-156 amp u see on the pix page.? ?He redid them , this time on the side of the cabs,, and mounted to? some? square? HV? micarta...+ nylon screws.? When I had it, one day the line V went up to? 247 V..and? B+? rose to a hair under? 7 kv.... and it arced from center to? one of the 2 x SS mounting screws !? ? ?Also, when I got my arm? within 1' of the silicone rubber coated belden 10 kv test prod? wire, all the hair on my arm stood on end, which really? freaked me out.? Most of these? HV connectors have one issue or another.? ?Even the Alden ones are not perfect, and are easily pulled out, no locking? provision.? ? The better types use a braid over the dielectric, like? 393 /213? etc, and are configured such that the braid /shield? always makes? contact? 1st..... just b4 the center? conductor? connects.? On this latest? B+? supply I'm building,? I'm hard wiring all the B+? connections, where the 393 cable goes external? from the HV supply, over to the 2nd cab, which contains the C1 -L-C2? filter, then more? 393 over to the 3rd cab, which contains the RF deck.? Then lugs on the center conductor and braid, strain relief? with a plastic clamp? on a 1" diam stand off, then more strain relief where it exits the cab with those rubber? reducing fittings, that cinch down on the? cable.? ?I'm done with hv connectors,? they all have some kind of? drawback, or are bulky.? On the inside of the cabs, I used plane jane Belden? 10 kv rated? test prod wire,? 18 gauge, with the silicone rubber insulation...super flexible.? ?Good on the inside of a cab,? but I would not use it external, not robust enough, and silicone rubber is too easily pinched, nicked, etc.? You could slice into it, and the cut slit would self heal, and you would? never know there was a cut into it.? I have? 200' of 393? coax, with its teflon dielectric over the center conductor and also over the silver plated braid.? ?Then ground the braid at each end.? ?Then a? separate 10 / 8 gauge, insulated wire,? with lugs on each end,? bonding the cabs together.? ?I only need a few? feet for the external? HV wiring.? On that YC-156? supply, besides a HV meter in both the HV supply, with its 4 x oil caps etc,? I also had a HV meter in 2nd box, with the? 20 x lytics..and a 3rd? HV meter in the RF deck.? ?IF? HV fuse blows open, the HV meter in the RF deck drops to zero, while the other 2 x hv meters? still reads 6.7 kv.... being on the inboard side of the HV fuse.? ?Also wired 2 x? green neons in series, then wired that mess across the last lytic in the series string, at the cold end.? Works good, and you can see the pair of green? neons? ?from? 50'? away.? ?Good visual? attention getting device.? ?Any box that has HV inside, gets a HV meter.? Another problem with the millens is there is no provision for strain relief.? Jim? ?VE7RF? ?? ? ? ? ? |
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Re: 'Toll free' gets blasted with 6 kv !
¿ªÔÆÌåÓýWhy would he be crazy enough to do that? Didn¡¯t he know they are only rated for 2~2.5KV????? ? Mod-U-Lator, Mike(y)/W3SLK ? ? ? From: ham_amplifiers@... [mailto:ham_amplifiers@...]
Sent: Wednesday, December 19, 2018 10:21 PM To: ham_amplifiers@... Subject: [ham_amplifiers] 'Toll free' gets blasted with 6 kv ! ? ? I heard through the grape vine that? toll free / aka? Shane,? /? KD6VXI,? just about blew his finger off, on a Millen HV connector, with 6 kv on it.? ?Don't ever get near one of those things, when there is B+ on it.? ? Jim? ?VE7RF |
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Re: 'Toll free' gets blasted with 6 kv !
¿ªÔÆÌåÓýOh no! That is no laughing matter.I have a mate, who, 25 years ago, touched 3kV in his 4-1000A amp. When he came to, he was slammed up against his shack wall, 6 feet from where the amp was. Take care Shane. Best wishes mate. Alek. VK6APK On 20/12/2018 11:21 AM, jim.thom@... [ham_amplifiers] wrote:
-- From sunny Binningup Family Businesses: SP Electrical. The Velvet Fox. Smart Design Electrical. Perth Interiors. |
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New PSUD-3 now in the works !
I keep finding anomalies? with? PSUD-2.? Like when a plane jane? L-C??
filter is used, the +? and? -? peak V? across the? choke is beyond? sky high...
like? 17 +? KV? ! I tried every possible LC config? you can think of, and still get? sky
high? V across the choke.?? Also tried increasing the input Z of the plate xfmr,
and increasing the ESR of the filter caps, lowering the B+, and also? varying the steady state
load on the supply.? Using the stepped load feature of PSUD-2, like idle current
to normal full bore plate current.... or vice versa,? still bad results.? ? Another? issue is when a glitch resistor is used, like typ a HV fuse
inserted? in the B+? line, followed? by the? glitch resistor,? PSUD?? wont
allow? you to insert just the resistor. It wants to see a RC network tacked onto the existing? filter.?? To get
around that,? I used? .01 uf.... which is the smallest value? PSUD-2? allows to
be used.??? The idea being the .01 uf is the? bypass cap at the cold end of the plate choke.???? OK, now
the problems start.? PSUD-2? P-P? ripple? goes nuts, and very ..spiky.?? Once
the C2? cap is increased to .03 uf, then the anomalies and spikes? vanish. ? Also noted is that a C-L network or a? C-R network does not improve the
p-p? ripple at all,? none.?? P-P ripple is the same as just a plane C
filter. ? I was experimenting with both a C-L-C and also a C-R-C? filter setup.?? But
once the additional?? glitch R? +? bypass cap was added to the mix,? ripple
results are spiky. The bypass cap value has to be increased to... fool the? PSUD-2? software.?
? If a HV fuse used, followed by a glitch resistor....and? B+? arcs to
chassis, or the grounded grid inside the triode, then its an eye opener.?? Peak
fault current goes sky high, then HV fuse opens? up? <? 2 msecs later.?? The back emf on the? choke
is? sky high.???? Even if a glitch resistor? +? HV fuse were not used,? and B+
arced,? and mains? breaker /? fuse opened up, this may still explain choke failures? on henry radio amps. ? A? C-R-C network will reduce? the? ripple in half, vs just a? C? filter by
itself.? C filter in the 2nd case would be just the?? C1? +? C2 caps? in
parallel. A? C-L-C? filter? will reduce the ripple down to nothing... like? -113
db.?? Ripple on my drake? supply is? -30 db. ? Duncan? Monro,? M0KGK? responded? a few? hrs ago, that he is working on?
PSUD-3.?? IF any of you that use? PSUD-2? note any screwball? results, he needs
your files asap. The idea is the? offending parameters, anomalies,? can be tested on the new
PSUD-3 version,? before releasing it. ? There are a? few other items that need to be addressed, like?? outputting
ripple results in? peak to peak,? and also in RMS, and also in ¨C XXX? DB.?? For
commercial use, expressing ripple in ¨Cdb is typ.? Although the stepped load feature of?
PSUD is useful, it does not simulate a real world varying load, like you would
have on SSB, AM, or an audio amplifier application.?? IE:? a real world? dynamic load.?? The
stepped? load feature on PSUD-2? either removes the load asap, or slams a load
on asap. Thats? good enough for cw use..and thats it.?? The current version of?
PSUD-2? will depict?? RMS ripple current into the C1? and also C2 caps.?? It¡¯s
the only tool I have found that will at least depict? ripple current into a simple C filter... which is?
typ?? 2 to 2.5? times the loaded DC current.? Which also explains why some caps
will internally heat up using high duty cycle modes like data, AM,?? FM etc,?? and or? dry out
quicker.?? Typ larger value caps also have higher? ripple current ratings.
? Filter ringing, overshoot,? and number of cycles? before the? ringing
subsides..and also? LP filter cutoff? need to be addressed.?? As is,? PSUD-2?
will only handle? single phase power supplies, and only? a choice of 50-60-400 hz.???? 3 phase? would be an excellent addition... but there are
also? typ 3 ways to design the? 3 phase supply.? ? What else that needs to be addressed is? ripple at the harmonic freqs,?
like??? 240 hz, and also? 360,? 480, 600 hz, etc.?? IF in the UK,? Japan etc,
then its 100-200-300-400-500-600 hz.? On single phase,? ripple Freq is? just 2
F.?????? On 3 phase, ripple freq is now? 6F, so ripple is at? 360, 720 hz? etc.
? Hopefully, the anomalies? and enhancements?? will materialize.?? If anybody
has other ideas for? PSUD-3,? Duncan can be reached at duncan@...?? or??????
postmaster@...? ? The idea is to get? PSUD-3? to a pro level.?? Its used by a lot of folks (besides hams)? ?world wide, but as is, it has limitations. ? Jim? VE7RF
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Electrolytics with studs out the bottom, WARNING !
For you folks that come across? ?lytics, like the? 450 vdc variety, that have a threaded stud? (typ? 12mm threads, that stick out the dead center of the bottom of the can by? typ? 1/2")? look out, the threaded stud? will read? zero ohms, between the stud and the NEGATIVE? terminal? ?at the top end of the can !?? Strung in series, the lytics have to be insulated? from each other..and? chassis / ground.? ? Usually? when they have been used,? folks will? drill? an undersized hole, then? tap with a 12mm? tap.... and? typ into? 3/4" wood.? I can see that being a potential? source of either leakage / fire hazard etc.? ?With say? ?300-400? vdc? across? each lytic, the V potential? between? ?studs is also 300-400 vdc.? ?3/4" wood, and loads of spacing between? studs is probably not that big a deal,? except in the case where? 9-25 caps? are used.? ?Typ with 9 caps, they are arranged in a 3x3 matrix, and wired like a snake..in series.? Ditto? with? ?16 x caps in a 4 x4 matrix,? I have seen? 24 caps in a 4 x 6 matrix.? Mine is? 25 caps in a 5x5 matrix.?? The caps? towards the hot end have one helluva lot of? B+ on em... and you don't want studs close to angle aluminum, which is typ what's used to support the 3/4"? wood etc.? You also can have a huge potential? ?if the? 1st and last cap are close to? each other, like adjacent, as is sometimes done on the last row,? done so the? B+ and B-? leads? are also close.... which is? really not a smart idea.? ?Even wired in the normal? snake routine,? Cap? #1 is at hot end.... and? cap? # 10? are adjacent...with a? 2772 V potential? between. their adjacent studs..and as much as? 7700 vdc between cap #1..and any? supporting angle Aluminum on the underside of the UHMW / wood etc.?? Mine are going into? 1" thick? UHMW sheeting, also drilled and tapped for the 12mm stud threads.? ?To support the weight of the? 25 caps ( at 3.3 lbs each =? ?82.5 lbs),? 2" x 2"? angle aluminum? is run down each side of rack, front to back.? ? ?Flat side up.? ?UHMW? sits on top? of the angle Aluminum.? ?Problem is, the rack is? 24" wide and not? 19"? wide.? ?1" UHMW is not as? strong as you think, I tested it with weight, it will flex.? The fix for that is some more? 2x2? angle aluminum running transverse, across the? 24"? width of the UHMW, but underneath the UHMW,? to support it.? ?Those transverse pieces? ?bolt to the underside of the Al pieces that run front to back, down each side of the rack.? But that also leaves a gap? ( = the thickness of the al used? that runs front to back, down each side).? IE:? ?UHMW? won't sit flush to the transverse supporting AL, but? 3/16" to 1/4"? above it.? ?The fix for that is yet another sheet of UHMW,? like? 3/16 -? 1/4"? thick, to fill in the gap, but? 4" narrower, so it sits flush to the edges of the front to back al.? ? It's that OR cut the transverse supporting pieces shorter, so they sit flush? to the edges of the front to back al, then there is no gap.? ?But then the transverse supporting pieces? ?are not supporting the last 2 " of the 1" thick? UHMW? down each side.? 82.5 lbs? (? + misc stuff like? eq resistors +? 50 x 10-32 screws etc, etc ), even though evenly distributed? in a 24 x 24 rack , is a lot of weight to support.? ?Worse is me trying to slide a completed, populated? sheet towards the? top of the? 6' tall rack.? ?Since the front / rear /and both sides are all quick release type,? it's almost? easier to mount the? pre-drilled sheet in the rack 1st, bolt it down, then? start screwing in? ?studs, one at a time, down the middle? row, (#3) ,? then? installing eq resistors etc, then adding the row on either side of center,? ( rows #2 +? #4)... then rows # 1 +? #5? dead last.? ?Then repeat for 2nd bank of? another 25 caps, lower down in the rack.? Then the misc HV fuses, and the? 127 lb dahl choke go in the bottom..or close to the bottom.? From a safety view,? each bank of caps will get it's own dedicated? ?B+ meter.? ? Other cabinet with the 50 ohm glitch assy, B+ fuse, 2 x parallel diode boards, + plate xfmr etc, will? also get a dedicated B+ meter.? ? Each RF deck gets? 1 x B+ meter....so 5 all together.? ?IF the? choke went open, and NC vac relay engaged, so choke is in the circuit,? each bank of caps would be independent, with an open between em..and both? charged up to max B+.? ?IF the B+? fuse just inboard of glitch Resistor opened up, the? B+ meter in the RF deck will read zero... meanwhile both banks of caps have full B+ ..which of course is lethal..since they are still being fed from the plate xmfr and diode boards.? ?Any box I have that has B+? in it, gets a B+ meter.? ?Normally that's one in HV supply..and a 2nd HV meter in the? ?RF deck.? But in this one off case, the filter caps and choke are in a separate rack from the? xfmr + diode boards.. so 3 x racks in all for? the entire mess... for just 1 RF deck.? ?2nd RF deck goes into yet another rack (rack #4).? After this gong show is done, that's it,? no more RF decks and B+ supplies for a while.? ? ?It's? over the top as is.?However, the ends justify the means, lol.? ? |
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Re: C-L-C, bad news
<Randy Nov 25 5:50 PM <Or, would you have to parallel them? I'm thinking that's the right answer. <Randy #? Neither of your?
schemes will work.? ?I? just? went through this with dahl / hammond.? ?However,?
Wire wound resistors can be wound, in such a fashion that they have little or no
inductance, using a criss cross? winding pattern...... end result is not as good
as a globar resistor,? but good enough for a lot of applications.? ?The same
winding pattern doesn't work for a choke, it would kill all the inductance,
which is what we are after.? 2 x 2H? chokes in series = 4H....and? 2 x 2H chokes
in parallel? =? 1H.? ? ?There is no way to get around the back emf
either...except? for a spark gap.? ? When u see the back emf? on? PSUD software,
it swings back and forth in polarity, getting a little weaker each time.? ?On
paper, the spark gap? should trigger on the? 1st back emf, which is always
opposite? polarity..... which is why you see stuff like a rvs connected diode
across a TR relay? coil. The back emf is large, and obviously has more than .7
vdc? to turn the diode on.?? ? ##? But trying to
handle 12-14 kv..and who knows how much? current in the emf,? is dicey use of
diodes.... hence the simple spark gap.? ?Then the gap can be? set real low as
practical, like just a few thousands of an inch.? ?Spark gaps? don't care
whether it is? AC? /? DC? or what the polarity is.... they just fire.? ?And the
only time the spark gap is gonna fire, is if the? B+? 1st? arcs to grid, or
chassis, resulting in 150A? fault current ( limited by the glitch R)? ?which in
turns blows open the HV fuse, just b4 the? glitch R.? ? ##? This? ?4 H? /
127 lb dahl choke is a behemoth.? ?If it wasn't readily available, I would not
have tried this stunt.? ?Playing with PSUD, a simple 10 ohm resistor? ?between 2
x caps... like a C-R-C network? ?works damned good,? ?Ripple is reduced to?
1/3? of the? ? ?C-C config.? ? ?The? choke, in a C-L-C? ?config results in
ripple being reduced? to? 1/550? of the? ?C-C config.... which is beyond gross
max? overkill.? ?
##? A? 10 ohm
resistor,? with? 2-3 A? CCS flowing through it,? develops? 40-90? watts of
heat... no different than a 4 H choke? with 10 ohms DC resistance.? ?But a 10
ohm /? 100-225 watt wire wound is dead simple, dirt cheap..and weighs
nothing.?? Later.... Jim? ?VE7RF |
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Re: 10A07-T vs 6A10 diode
<Alek Petkovic Nov 24 2:43 PM <I have not heard of 10A07s at all but Ebay is full of suppliers selling 10A10 diodes, which coincide with the <specs you quoted. <73, Alek. <VK6APK ##? 10A10's? are sold by? Mouser et all, in the USA.? made by Rectron.? Rated at 1 kv piv? @ 10A. But they only have a 400 A surge rating.? They also require a 1 square inch heat sink on the PC board they are soldered to.? ? Strung in series, you need? 2 square inches, like a 1" tall? x 2"? wide foil on board, with? wire from each? diode terminating dead center in the center of each 1"? square .? ?$48.30? per? 100.? ? ##? The 10A07? spec is here.? ? ? Rated? at? 1 kv? piv? @ 10 A.. BUT this? version has a 600 A? surge.? Made by? ?Diodes incorporated.? ? ? ? ? $42.00? per 100 ##? 6A10's? are still the cheapest... and still have a 400A? surge rating.? ?$15.50? per 100.?? ##? Prices are all over the map, depending on maker etc.? ?Mouser list abt a doz different versions of each type.? ##? all 3 diodes,? 6A10 /? 10A10 / 10A07? ? are the same diam / length / wire gauge out each end.? The 10A versions need the heatsink on a? board, and that's? going quite a bit horizontal 1st, out each end, b4 u do a 90 deg down into the board? / 1 " square heat sink.? ##? IMO,? In practical terms,? if a 6A10? isn't big enough for the job,? 2 x 6A10's in parallel? ?will do the job, and are still a big bang for the $. ... and no heat sink required.? ? 2 x 6A10's would be good for 12 A..and a 800A? surge...and still be cheaper? ?than a single? 10A10 / 10A07.? ##? In my case,? I used? 2 x separate? FWB? assy's.... in parallel .? ?24 x 6A10's per? each of the 4 x legs to make up one assy....? 96 x 6A10's in total.? ? ?And? 96 more for 2nd FWB assy.? ?Both assy's? in parallel.? ##? If I had to do this again,? ?I'd? use 2 x 6A10's? ?in parallel? to make up..."1 big diode".? ? 192? diodes still used either way.? ?Just leave the leads of the? 6A10 long, cuz that; is the heatsink on em.? ##? I use? 4-6 of em in parallel, to make up? one big? ?'safety diode'? that goes between B-..and chassis.? And? 2 more in parallel,? but rvs connected, also wired? B- to chassis.? Then the B-? is never more than? +/-? .7 V? ?from chassis? potential.? ? In the case of a? B+? ?to? chassis? arc, or? anode to grid arc, the? ?1600-2400? A? surge rating of the? paralleled 4-6 x diodes is ample.? The fault current? with? 7700 +? 50 ohm glitch is only? 154 A..and the? HV fuse opens up? in well <? 2 msecs.? Cro-bar the B+? all u want, those paralleled 6A10's never short out.? I usually buy em? by the 100, or? 250 qty.? ?And just use em on everything.? ?They work really good for bias for a GG amp, when loads of em are used in series.? ?My bias board uses? ?49 of em in series, then? tapped? ?with a rotary switch.? Then a big? 43,000 uf? @ 50 vdc? lytic across all? 40 of, then the bias? doesn't budge.? So far, so good.? Jim? ?VE7RF |