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Re: henry 3k/8k choke input HV supply
Then, if we talk 3-phase supply and 6-puls rectifying,
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lets say around 5 kV DC potential, how much glitch C is needed to achieve 1.5 percent ripple? Forgot how to calculate it, must dig out books to do it. 73 Jim SM2EKM --------------------------------------------- pentalab wrote: ### You want to shoot for 1 to 1.5% ripple in a C input HV supply.... then you can also be assured of good dynamic reg. |
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Re: henry 3k/8k choke input HV supply
craxd
Jim,
Yes, your correct on the 3-5% ripple for the plate tranny. I was thinking of the low voltage DC supplies when I wrote that. Sorry, my faux pas. The formulas are written around 5% actually since they feed supplies for all types equipment including test equipment like RF generators, etc. I agree the cleaner the better, but that can be hard to do the lower you go under 5%-3%. More C = More clean, but more current from the tranny and through the rectifiers. Manufacturers design for the bare minimum over the cost of the transformer, and the caps IMHO. The formulas was for the rms tranny current for the secondaries. In other words, it takes 1.8 times (1.8 by Stancor and others, and 2X for 100% duty cycle) the DC load current for a C input full wave bridge at around 5% ripple or less (Hammond says 1.6 X). Now you multiply that by the secondary voltage to get the secondary power, then multiply that by the losses (wire I^2 R and core) found by the efficiency (for large cores around 85%), and that's the primary power since primary power = secondary power plus the losses. After that, multiply by the power factor which is generally 0.9 according to the "Reference Data for Radio Engineers" book. On the resonant choke, I had read a little more since that comversation, and seen the part about designing for a bit above 120 Hz somewhere on the net. To me, it's more worry and complicated than what it's worth. I'll bet it never works the same between each amp they build either. I also never did complete the project after all I read about it. Matching the choke to the caps is about the only way to do it. Also, one would have to run the amp so the rated current would always be where it resonates, or it wouldn't do any good. The reason why the Hammond trannys would run hot is probably where they spec them smaller than the others using the 1.6 X DC current figure. They're the only ones that do it I've seen from a Ton of research I've done on the subject. 1.6 would probably be ok for SSB only. BTW, The group at Wikipedia that deleted the transformer info had me to do a complete new page named transformer design. Take a look, though I've not finished it completely. There's 1-2 from the transformer page helping me with it after all the discussions went over. I'm only going to do the power transformer portion. For audio and RF, others can do it. See; Best, Will --- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote: a 'minor' flash from the sandfilled fuse. Nothing gets blown up. |
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Re: Hi-
pentalab
--- In ham_amplifiers@..., "Hsu" <Jbenson@...> wrote:
ham_amplifiers. Hsu### Yes HSU. We were wondering why it took you so long to find us !! LOL ### You can talk about 811-A's all you want here. And nobody is going to suggest boycotting Chinese made products, Chinese gov't, or Chinese radio amateur's either ! Welcome aboard..... Later.... Jim VE7RF |
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Re: henry 3k/8k choke input HV supply
pentalab
--- In ham_amplifiers@..., "craxd" <craxd1@...> wrote:
Jim, that the transformer can be smaller than one for a capacitor input by a good bit. Most transformer manufacturers give for a choke input, the rms current is 1.2 x DC current, and for a cap input it is 1.65 (Hammond only) to 2 X, with most saying 1.8 X. ### I'm assuming you are refering to PRI AC current ?? Dahl sez for his hypersil C cores... take the DC INPUT power and multiply by 1.21 to calculate PRI KVA power. [21%]. 11% of that comes from a power factor of .9 and the other 10% comes from cores losses. So what's he's telling me is that the ratio of KVA input power to DC watts is 1.21 ### When I measure these old Hammond's [80 lb units designed for choke input supplies, IE: high reactance types] when used in a C input filter set up... I typ get pri KVA is always 1.35 x higher than DC input watts [load of the amp] . ### BTW... all these old hammond xfmr's used a 2 x choke setup.... all of em. The 1st choke was I think, a hammond fixed choke... followed by 2 x oil caps.... followed by a hammond swinging choke... followed by another 2 x oil caps. ### These 80 lb Hammonds were typ 3450-0-3450... and had a 0-110- 115-120 V primary. They were all rated at 2.2 KVA . DC wise.... they were rated for 3000 Vdc @ 500 Ma CCS.... and 750 ma ICAS. Sec DC resistance, end to end was typ 135 ohms. ### One of em... in C input filter... would run hot as hell... running a single 4-1000 @ 1900 w pep output. Two of em would work [then u could run em on 240v} Total weight 160 lbs. Two of em would again run scorching hot.. with a 2 x 4-1000 amp. ### Their biggest drawback is the 3450-0-3450 sec... and the 120 v primary. The turns ratio is a whopping 6900/120= 57.5 !! The difference is the rms voltage of the choke input transformer has to be higher than that of a cap input to match the same DC voltage. A resonant choke has to resonante at the peak current draw, so the cap and chokes (Lcrit) critical value has to match that figure. The only problem, there's no resonance at idle current. You still get the filtering of the choke, it's just not resonant to where the ac portion would be killed down like it is at the peak current. So, Lcit has to be selected at the peak current. See a copy below from a conversation between Peter G3RZP and I from the Amps archives. at 15%, and one at 30% if I recall. I've never heard of 9% regulationbe. ### And big wire to the main panel.. and big contactor's etc. A lot of this V sag is coming from the HUGE peak current every 8.3 msec x dc resistance of all the wiring, contactor's , breaker's,lugs, etc. All that stuff has to be oversized.... or bye bye V regulation.... never mind the plate xfmr/caps. you have a core with a larger window, one with a smaller, and both with the same weight, the smaller would have more core area and thus be capable of more watts out. This holds true especially in C- cores. I always did wish Bill Orr would have never said something about using weight for transformers in his book. ### agreed. I wish Orr would have NEVER mentioned the nonsense about.. "IVS ratings".... Intermittent Voice Service !!! which was based upon unrealistic low duty cycle figures of 25 % [ it's 50% average on any plate current meter]. They also factored in.. I talk... then listen for 15 mins.... during a 5 x way roundatable. They also FORGOT the idling current from the tube[s] ... which throws all the cals out the window ! ### Don't laugh. TEN TEC still brags about their 7 kw IVS rating of the xfmr in their Centurion 2 x 3-500Z amp. They rate the xfmr at 3.5 KVA CCS. The amp is one of these "almost legal limit" jobs by the factory/QST. It will NOT do 1.5 kw output RTTY. It's designed to do 1.2 kw output PEP on ssb... that's it.... just like a stock SB-220. destroy more stuff than need be. ### Easy fix.... install a 50 ohm glitch R. For a 7900 V supply with 135 uf filter cap.... and running up to 3 A of plate current... we used a pair of 100 ohm 225 W CCS wirewound resistor's in parallel. These are cheap... right outa the mouser/digikey catalog. The glitch R assy.... is PRECEDED by a Buss 3 A HV fuse [HVU Sandfilled type] ### I can short the +7900 to chassis.. or anything else.... just a 'minor' flash from the sandfilled fuse. Nothing gets blown up. We tried it 12 times so far in this latest project. A ripple factor of 10% or less is all one really needs. If one sticks with the published formulas by the transformer manufacturers, you can't really go wrong as they did the tests to come up with them.### 10% ripple would sound like crap over the air ! Both Orr and ARRL always have quoted 5% max ripple for cw... and 3% for SSB. Those are still the bare minimum's. A L4B is 3%.. at max load.... so is A SB-220 TL-922. Heck, back then the biggest lytic was only 200 uf @ 450 V. ### You want to shoot for 1 to 1.5% ripple in a C input HV supply.... then you can also be assured of good dynamic reg.
. I've never used a swinging choke in### It would NEVER work. You want the choke and resonating cap to resonate a BIT above 2 F... or aprx 125 hz. You will never see a swinging choke in a resonant choke set up. John Lyles sez they actually ship the resonating caps to the choke builder... who designs/builds the choke around the caps. . If you get the wrong resonant condition, you can get enormous voltages built up too, so this is not anexercise for the guy who isn't experienced in working on HV circuits. Tom, W8JI, has a frightening story about that, which you'll find somehwere in the Amps> ### W8JI scrwed up.... and thought for max ripple reduction... you resonate the entire mess at 120 hz ! If you do that... peak voltages will soar, and the biggest flash over you will ever see. The trick was to resonate it slightly above 120 hz... around 125-128 hz. I read the story. All he had to do was slightly DECREASE the cap value... the 2nd time around. There was no 2nd time around. ## You will notice in the 8K/3K manual... they use 3 x resonating caps in parallel with the choke... when power is 50 hz. When on 60 hz... one cap is removed... and only two are used. later Jim VE7RF |
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Supplier needed
craxd
All,
At one time, I had the address and phone number for a supplier around Dayton or Cinci Ohio for transformer related supplies. They carried paper, varnish, wire, hardware, and lams. EIS I know about, but they dont carry lams. Does anyone on here know who that might be, or have anyone that they might recommend? If so, please let me know off the list. I know there's a lot of suppliers around Los Angeles, CA. That would be no problem. Thanks in advance. Best, Will craxd1 at cerizon.net |
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Re: copper tubing prices. .
Peter Voelpel
For higher power I use 3/8" on 160m, 1/2" on 80+40m, followed by ~3/4" on
the higher bands. I do my silver plating with a homebrew mixture. When I had no other stuff on hand, I once used sugar to fill the copper tube before winding it, gave a nice smell after firing it up at high power, as not all went out that easy ;-). For much less then 8K I built 6 monobands amps 5K out. I always prefer tetrodes... 73 Peter ________________________________ From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of pentalab ### LOL ! I typ use 1/4" 3/8" and 1/2" [6-9-12 mm od] ### chek out what Multronics wants for say 1/2" tubing coil stock... like a 14 uh coil.... you will gag.. and have sticker shock. $8,000 for a new alpha. I can buy a helluva lots parts for $8 K. ### You don't need much tubing to wind a typ tank coil. I used 1/4" for the 160m portion...... 3/8" for the 80-40m coil..... and 1/2" for the 20-17-15m coil. Anybody who is thinking of using these big triodes on 10/12 m... is well advised to use 3/4" tubing... or 1.5" wide strap. [typ 2-3 turns.. 3" ID used on 10/12m] ### They are easy to silver plate too... with "cool amp" from Ore. 3/8" and up will flatten on you, when wound... width is greater than the height. [looks cool] If u want it perfectly round..... fill the tubing with either rocksalt.. or sand b4 u wind the coil. Use an air compressor to blow out the sand when done. With rocksalt..... just toss the completed coil in water... and let it disolve. Later....Jim VE7RF <mailto:ham_amplifiers%40yahoogroups.com> [mailto:ham_amplifiers@... <mailto:ham_amplifiers%40yahoogroups.com> ] On Behalf Of pentalab |
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Re: henry 3k/8k choke input HV supply
craxd
See below,
--- In ham_amplifiers@..., "pentalab" <jim.thomson@...> wrote: ! Jim, My guess for the reason Henry used a choke input power supply was that the transformer can be smaller than one for a capacitor input by a good bit. Most transformer manufacturers give for a choke input, the rms current is 1.2 x DC current, and for a cap input it is 1.65 (Hammond only) to 2 X, with most saying 1.8 X. The difference is the rms voltage of the choke input transformer has to be higher than that of a cap input to match the same DC voltage. A resonant choke has to resonante at the peak current draw, so the cap and chokes (Lcrit) critical value has to match that figure. The only problem, there's no resonance at idle current. You still get the filtering of the choke, it's just not resonant to where the ac portion would be killed down like it is at the peak current. So, Lcit has to be selected at the peak current. See a copy below from a conversation between Peter G3RZP and I from the Amps archives. On transformer regulation, the voltage sag I've found on most all transformers in better built amps runs about 12% to 14% (I always figure 13%). I've never seen the 10% value listed in most books. Heathkit had worse regulation than this in a few models starting at 15%, and one at 30% if I recall. I've never heard of 9% regulation anywhere. I guess you could reach that, but you'd have to have a wheelborrow full of caps, and a lot bigger transformer than need be. You have to watch at sizing transformers by weight as that always don't hold true since it has to do with the design of the core. If you have a core with a larger window, one with a smaller, and both with the same weight, the smaller would have more core area and thus be capable of more watts out. This holds true especially in C-cores. I always did wish Bill Orr would have never said something about using weight for transformers in his book. The problem with a bunch of capacitance is when something shorts, there's a lot of joules of power released at once which can destroy more stuff than need be. A ripple factor of 10% or less is all one really needs. If one sticks with the published formulas by the transformer manufacturers, you can't really go wrong as they did the tests to come up with them. Quote from Amps; Because the critical choke inductance in a choke input filter varies inversely with the current, the swinging choke can have less air gap i.e. less reluctance than a non swinging choke. This means that it needs less wire for any given inductance, and so can be smaller. As the air gap is reduced, so the flux density in the iron goes up - less reluctance - so the number of ampere turns needed to start reducing permeability reduces. Now look at the numbers. Suppose we have a 2kV supply with a bleeder current of say 50mA, which is still 100 watts of heat. Now Terman gives Lcrit>R/1130 = 40,000/1130 = 35.4 Henries for a 60Hz single phase full wave rectifier. At 1 amp, however, we only need 1.77H. So you can see why a swinging choke is used. Interesting question: if the transient performance is so bad, why were swinging chokes considered OK for Class AB and B audio amplifiers used as modulators in AM tx's? Anyway, back to the point. At 120Hz, the reactance of 35.4H is 26.7K If we used a 20H choke, the reactance is 15.08K. Now shunt that with 0.08 microfarad. The result is 1[1/(-jXc) + 1/(jXl)] equivalent to 221.2 Henries, so we've made a small choke look like a much bigger one. the resonant frequency is 125.8Hz. ( f = 1/ 2pi. rt LC) Now this is all rather idealised insofar as no account has been taken of the choke resistance, which will modify the resonant frequency (resonance being defined as the frequency at which the circuit dealt with as a one port looks purely resistive) and the effective inductance. But you can see that adding the 'tuning' capacitor makes the choke look like a much bigger choke. Now if a swinging choke is used, as the current increases, the choke inductance drops, but that doesn't matter as long as the circuit still offers more than critical inductance. My suspicion is that a swinging choke provides worse transient regulation because when the load decreases, until the domains within the magnetic material can start de-aligning, i.e. getting further away from saturation, the choke critical inductance is too low, so the volts start to swing up. In any case, you have a parallel tuned circuit with varying current, so there will be a biggish transient. I would have thought that a fairly big output capacitor would cure this from the viewpoint of the load, but the rectifiers could see a large PIV. I've never used a swinging choke in a tuned choke system, though. Nevertheless, all chokes with iron cores change inductance to some extent as the current varies - some more than others. As Will said, tolerances mean that very careful choice of components is needed if you are to be certain that the choke is tuned HF: if you tune it LF, it will look like a lossy capacitor and the whole thing will revert to a capacitor input filter. If you get the wrong resonant condition, you can get enormous voltages built up too, so this is not an exercise for the guy who isn't experienced in working on HV circuits. Tom, W4JI, has a frightening story about that, which you'll find somehwere in the Amps archives. I find a Variac very useful at this early stage of the game: later, when you want to get realistic loads on the PSU, the Variac isn't such a good idea - they're not renowned for their regulation. 73 Peter G3RZP End quote. Best, Will |
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Re: SB-200 newbie question
Bob Green
OK, I've got the grids of the 572's grounded through 33 ohm resisters in
parallel with 940pf of capacitance. No smoke!!! Plates are NOT glowing!! I'm getting a reading of approx 80-90 ma of plate current as read on the meter. This looks normal, as far as I can remember. Things are looking up! I must be really dense, but I still don't know how to hook up the meter to read grid current though. Can anyone help, PLEASE! 73, Bob Green W6BBL w6bbl@... All email scanned by the latest update of Norton Anti-Virus 2006 and is certified to be 100% virus-free. |
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Re: copper tubing prices. .
pentalab
--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...>
wrote: ### LOL ! I typ use 1/4" 3/8" and 1/2" [6-9-12 mm od] ### chek out what Multronics wants for say 1/2" tubing coil stock... like a 14 uh coil.... you will gag.. and have sticker shock. $8,000 for a new alpha. I can buy a helluva lots parts for $8 K. ### You don't need much tubing to wind a typ tank coil. I used 1/4" for the 160m portion...... 3/8" for the 80-40m coil..... and 1/2" for the 20-17-15m coil. Anybody who is thinking of using these big triodes on 10/12 m... is well advised to use 3/4" tubing... or 1.5" wide strap. [typ 2-3 turns.. 3" ID used on 10/12m] ### They are easy to silver plate too... with "cool amp" from Ore. 3/8" and up will flatten on you, when wound... width is greater than the height. [looks cool] If u want it perfectly round..... fill the tubing with either rocksalt.. or sand b4 u wind the coil. Use an air compressor to blow out the sand when done. With rocksalt..... just toss the completed coil in water... and let it disolve. Later....Jim VE7RF [mailto:ham_amplifiers@...] On Behalf Of pentalab |
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Re: HV Fuses.... and why we need em.
pentalab
--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...>
wrote: glitch resistors and magnetic breakers in the primaries of the transformers is all I need ### You gotta be kidding us right ?? 2 uf or NONE !! ### here in NA... although 3 phase power [typ 12.5 kv /14.4 kv and now 25 kv] is distributed all over town..... only one leg /phase of that appears in residential area's.... where it's dropped down to 240 /120 v [ they all use a grnded CT on the sec] ### Typ pole pig xfmrs are 25/50 kva for multiple homes.. and smaller for a single home in the countryside. How 16 homes can all share the same 50 KVA xfmr [and all have "200 A" service] is beyond me ! ### 3 phase 208v/120v is used for business's.... and condominium's, apartment flats etc. Even there.... each floor will only get 208/120 single phase power... per suite. They make special 208 v electric base board heater's. Stuff like 240 v electric stoves.. and 240V electric hot water tanks/ 240 v electric clothes dryer's.. are used on 208 v.... and just take a little longer to heat up. ### For a single phase RF deck that needs say 6900V @ 3A... a bare minimum of 34 uf will provide barely 3% ripple. A 100 uf filter will provide 1% ripple... and far better DYNAMIC Regulation. ## with a resonant choke set up..[single phase].. you could easily get away with far less uf [for a given amount of ripple]. ### with a 3 phase HV supply... BEFORE any filtering at all.... ripple is just 5%. [50% with a single phase supply] ### ripple freq on single phase is 2F [120 hz] It's 6F [360 hz] with 3 phase......... so if u have 3 phase... you are laughing..and at a huge advantage over us. ### These modern lytics I have been talking about will also have a 360 hz ripple current rating [always lower than the 120 hz rating] ## Dahl plate xfmr's are very low ESR [typ just 8 ohms of DC resistance on the sec]... are of low reactance type... and will easily handle 150-400 uf of filtering [that's right from Dahl himself].... they do. ### IMO 20-24 x 450 V rated lytics [esp the 2" x 4" types] weigh zip ..compared to any choke... and are a dime a doz on the surplus market....new.. in the unopened box. ### for ESSB purposes... 1.5 % ripple is about the max you want. My buddy doubled the uf in his AL-1500... we could all HEAR the difference right away. His HV dynamic regulation improved a whole bunch. His entire amp plays a lot better now. later... Jim VE7RF |
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Re: henry 3k/8k choke input HV supply
pentalab
--- In ham_amplifiers@..., "ad4hk2004" <ad4hk2004@...>
wrote: ### I looked at the 8k/3 k ultra manual I have [same manual does both amps]. On the 8k they use 5 x 20k-100w resistors. Diss is a whopping 300 W CCS..... presumably so the resonant choke filter will work. On the 8 k.. they used a 6000 V xfmr. .9 x 6000 = 5400 vdc no load. ### here's the kicker. IF just one bleeder opens up... the OCV plate V shoots UP to a whopping 6000 x 1.414 = 8484 V !!! Now the poor 3CX-3000A7 [rated for 5 kv] won't like it.... nor anything else in the amp. You are lucking you didn't blow up ur 3k ultra. ### I gave up on choke input HV supplies yrs ago. The resonant choke idea although a good one... is not so simple to implement. ## My feeling is one is better off to use a C input filter. The 8 k ultra's plate xfmr is flaky at best. They could have used just a 3800 vac xfmr..... which would require LESS turns on the sec winding.... which in turn would mean the xfmr coulda used bigger ga wire in the 1st place. ### Dahl does a roaring business selling a 127 lb 10 kva replacement xfmr + mating choke for the 8 k ultra. Stock, the 8k is only good for 2 kw out CCS rtty/ 3.5 kw pep cw/ssb.... then in real fine print on the schematic it sez..."200 w in... 5kw+ out". ### IMO... why put a ton of weight.. in the form of a choke in a HV .... better to put the added weight into the plate xfmr in the 1st place... but that's just my opinion. ### I had some 3 k owners e-mail me a while back.... they were in the 10m contest [where both cw/ssb modes are used the entire weekend]. The poor fellow had forgotten to change the plate V from High... to low... when switching from ssb... to cw. The HV supply bit the dust shortly afterwards. [smoked plate xfmr] ## Henry has gone through so many plate xfmr manufacturer's, I have lost count. The last supplier for the 3k/8k was ECA. And just b4 Henry went "outa business"... they dumped ECA as a plate xfmr supplier ! ## I know several fellows who bought the Henry 16 uf - 7.5 kv rated oil caps.... used em in 4-1000 amps.... and blew up the caps ! With the proliferation of the newer low esr lytics out there [loads of em on the surplus market].. for a new hb project, they can't be beat. The latest bunch I got are 50 miliohm and 10 A CCS ripple current rating.... small things too.... 2500 uf @ 450 vdc... and just 2" diam x 4" long. ## It just seems nuts to me to suck 300 W ccs of bleeder... then another 150 ma @ 5200 Vdc on idle [8k] on top of that. ### The 8k drops from 5400 vdc to 4700 vdc with a typ load. It weighs a whopping 350 lbs too ! Since the alpha 87-A will do 1.5 kw CCS... and the 8k will do just 2 kw CCS... I'd say Henry just lost it... in the weight dept. ### BTW... a Dahl 10 KVA CCS xfmr weighs.. "just 127 lbs" Later......Jim VE7RF
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Re: resistor's as grid fuses ...VS a real grid fuse holder.
Peter Voelpel
Copper tubing is quite expensive overhere now.
10mm diameter is 3,60 Euro/m, 18mm is 6,40 Euro/m. Prices are for small quantities of course. 73 Peter ________________________________ From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of pentalab and it's all dirt cheap....just like copper tubing. |
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Re: Umpteen to zero...
On Oct 2, 2006, at 1:15 PM, ad4hk2004 wrote:
I check in here every few days to count on my mental fingers how manyZzzz Denny == Have you checked the max V rating of Ohmite's 100W resistors? R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org |
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Re: HV Fuses.... and why we need em.
On Oct 2, 2006, at 12:41 PM, pentalab wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:Instantly is pretty soon.the grid current will skyrocket..... hence another reason for a HV fuses are not fast enough to prevent gold sputtering from the grid of an 8877, 3cx800A7, et cetera.You remove the HV on any GG amp... AND drive it, with just a### Fast fuses are called ..."rectifier fuses". The even The SB-220's 120J seems pretty real to me. A Buss HVU series, sandPeak current can go through the roof in under 1mSec. Been there. The original Plywood Box did 14-out PEP on SSB, it used a double 40A breaker and #4 Cu wire. I tuned it up with a 30pps, 30% duty-cycle tuning pulser, and it never tripped the breaker The HV dropped to c. 7800v on an ahhhhhh. What's wrong with that? A bare minimum for justPerhaps an indirectly cathode could be damaged by over-current, but directly-heated cathodes are naturally current limiting. The 8170 in the Plywood Box amp was not damaged during a number of big-bang parasitic oscillations, but I disintegrated a few glitch resistors before I figured out that a glitch-R is Not supposed to be a fuse. . cheers, Jim... R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org |
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Re: HV Fuses.... and why we need em.
Peter Voelpel
What is your reason for that large capacitor?
Are you using single phase at that power level? I only use 2?F maximum or none in my large power supplies, so my glitch resistors and magnetic breakers in the primaries of the transformers is all I need 73 Peter, DF3KV ________________________________ From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of pentalab ## Here's why. The last HV supply I designed used 30 x lytics... EACH is 3700 uf @ 350 V. We ran outa 3700 uf units for the last 5 caps.. so we used 5200 Uf units @ 350 V. ### The entire mess > 135 uf !! Since joules [watt seconds] goes to the SQUARE of the voltage..... u can easily see that the total joules is sky high..... has to be. You want to run 10 x the dc input as b4.... u require 10 x the energy in joules. |
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Re: resistor's as grid fuses ...VS a real grid fuse holder.
pentalab
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
RICH SEZ...Correct. Jim. My thinking on NOT using a fuse holder is that if the fusing element blows, the reason is not a defective fuse, it has to be the whatever that caused the fuse to blow, so a new fuse is not the total repair. Thus, when the fusing element blows, the amplifier has to be disassembled anyway to find the real problem, so a fuse holder would be of no advantage. ### Gimme a break ! The grid fuse could blow for several reasons.... like SKY high swr... accidental overdrive.... underloading, both..... OR if the HV fuse blew open [and with amp being driven, the grid current will wrap around the peg]. ## once the reason for the grid fuse blowing is known.... it can be quickly replaced... in mere seconds flat. Ditto with a cathode fuse. A little longer to replace either of the HV fuses. ### I can stuff a screwdriver into the HV compartment, grnd anything you want, short out caps, short the grid to the cathode... run 15 kw into a dead short, wide open,,, drop a wrench across the 240 v input, have the big Dayton blower crap out, lose air to the tube , lose commerccial AC power from the street, have transients, spikes , surges coming in off the street, overdrive the amp, underload the amp, etc, etc... and you STILL CAN'T blow anything up. I can even lay a dead short across the diode FWB rectifier board.... and not take out any diodes. ### I can also short out the fil xfmr, or short out the + 120 vdc supply for the sped up vac relays, or short out the +12 vdc for the plate choke relay. ### My goal was to make it [RF deck + HV supply] 120% BULLET PROOF!! Next step is to add the spark gap across the Vac load cap. [heck a spark plug in open air.. set to arc at 1.7 kv will work] We might add electronic grid + plate overcurrent protection later on... + a HV sensor [which will inhibit TX... with low, or NO hv present]. ### The beauty of HB designs is.... you can easily add any or all of this stuff in... at any time.... and it's all dirt cheap.... just like copper tubing. Later... Jim VE7RF |
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Umpteen to zero...
ad4hk2004
I check in here every few days to count on my mental fingers how many
times Rich rants on about Tom... Then I go to the other shrine and count how many times Tom mentions Rich... It's umpteen to zero at this point... One of em needs to give it a rest! - busily changing out 20K ohm, 100 watt, resistors in a Henry 3K Ultra PS.... Man a bad PS load resistor can sure contaminate everything when it decides to go open winding and arcs, sputtering crap onto other components... It took a bit of sleuthing to find the correct resistors for replacing... Turns out Newark has em in Ohmite brand... denny / k8do |
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HV Fuses.... and why we need em.
pentalab
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
the grid current will skyrocket..... hence another reason for a fast grid fuse. seems to me, both the plate current and grid current went beserko. instantly... RICH SEZ ..quite soon is more like it ### No, not quite soon,,, grid fuse blows asap ! instantly ! You remove the HV on any GG amp... AND drive it, with just a little bit of power.. you will send the grid current through the roof ! You drive it with full power.... and then lose the HV... the grid current will wrap around the peg 4 x over..... and blow the fast grid fuse. ### Fast fuses are called ..."rectifier fuses". The even faster ones of the bunch are called .."semi conductor fuses". You can even get fast .. "semi conductor fuses" up to 300 A ## You can get super fast fuses in 3agc.. anywhere.. like Mouser/digi key/newark, etc. ### Never had a problem with parasitics destroying a tube.. as long as glitch R installed... grid and cathode fuses... and a HV fuse. RICH SEZ... As I see it, a HV fuse is OBVIATED if the HV xfmr primary is fused. ### DREAM ON RICH Rich ! You gotta be nuts to leave out the HV fuse.... and soley rely on a typ slow breaker in the 240 V primary !!! The fastest breakers known.. are called "controlled Hydraulic magnetic breakers".... and the fastest of them .... still isn't fast enough. ## Here's why. The last HV supply I designed used 30 x lytics... EACH is 3700 uf @ 350 V. We ran outa 3700 uf units for the last 5 caps.. so we used 5200 Uf units @ 350 V. ### The entire mess > 135 uf !! Since joules [watt seconds] goes to the SQUARE of the voltage..... u can easily see that the total joules is sky high..... has to be. You want to run 10 x the dc input as b4.... u require 10 x the energy in joules. ### Even on a SB-220, L4B, AL-1500, etc.... the stored energy in the bank of lytics is just unreal. A Buss HVU series, sand filled fuse [sized right for the job] OR a HB hv fuse [ one fine strand between 2 x insulator's] will blow EXTREMELY FAST......<2- msecs. ### The ONLY way to speed up the primary 240 V fusing.. is to supplement the typ "controlled magnetic hydraulic breakers"... with super fast "semiconductor fuses" ....... or do like you do.... and use a 40 A breaker..... which BARELY handles the average load on unprocessed SSB. Of course, with a grossly undersized breaker.... you only have two options..... pulse tuning... and then straight to unprocessed SSB. Run a dead cxr... even for 2 seconds, just to take some steady state grid/plate/fil V readings.... and ur 40 A breaker will blow open !! To do 14kw out.... you need a 100 A breaker !! ### It's actually 106 A [and that's with 67% tank eff] ### Ur 100' of 4 ga wire has way too much loop resistance for the peak currents on the 240 v line. A bare minimum for just a 30' run is 2 ga. It should be 3 x 000 CU.... regardless of lenght. ### leaving out the simple HV fuse.. and relying on primary breakers is a 100% sure fire way to destroy stuff.. including tubes. RICH SEZ Also, a fuse is not as good as of a peak-current limiter as a glitch R. ### A fuse is NOT a peak limiter at all... never was ! A fuse's job is to INTERUPT CURRENT FLOW... that's it. The job of the glitch R is to LIMIT CURRENT. You need BOTH... and the glitch R should be 50 ohms.... even in a small amp. ### To really do it right... I install a 2nd HV fuse.... located between ONE leg of the plate xfmr sec... and the diode board... with this arrangement... there is NO way you can ever take out the diodes. ### also install one reverse connected 6 A diode ACROSS EACH lytic. ### In a small amp, use a 50 ohm 50 watt wirewound... OR 2 x 25 ohm-25 Watt units in series....[the 2 resistors can be several inches apart.. easier to mount in some apllications.] Later... Jim VE7RF |
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Re: Any idea's on a visual Grid / Cathode fuse indicating device ??
On Oct 2, 2006, at 12:15 AM, pentalab wrote:
--- In ham_amplifiers@..., Steven Grant <w4iiv@...>indeed IFquite soon is more like it As I see it, a HV fuse is obviated if the HV xfmr primary is fused. Also, a fuse is not as good as of a peak-current limiter as a glitch R. R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org |
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