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Re: C-L-C, bad news
I had an old either Navy or Air Force choke that had exactly that.? An adjustable spark gap across the choke.
-----Original Message----- From: jim.thom@... [ham_amplifiers] To: ham_amplifiers Sent: Mon, Nov 19, 2018 7:38 pm Subject: [ham_amplifiers] C-L-C, bad news
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? On paper, the? C-L-C is a superb output filter? for any B+ supply, reducing ripple to low levels.? ?Even with low value caps on either side, and a? ?2-4H? choke used,? it works superb.? ? I tried the? config and the theory works.
Ok, here's the problem.? ?IF the? B+? arcs to chassis, in? the RF deck,? ?or say from? anode to grounded grid, etc, then a huge fault current results.. only limited by the 50 ohm glitch Resistor.? ?2 msecs later, the? HV fuse, located just in board of the? glitch R, opens up.??
Fault current goes from 100 / 134 amps? ( depending on? ?5700 / 7700? config).? ? ?down to? zero....in <? 2msecs flat.? ? The? resulting EMF? from the? 4 H / 127 lb Dahl choke is nothing short? of insane.? ?Like? 10-14 kv.? It also oscillates back and forth in polarity, which charges up / discharges the caps? on either side of the? choke.? ?Current? going into both caps is also insane.? It like ringing a gong..and takes a several seconds to settle down.??
Same deal? ? if a 'normal'? ?L-C? config used, like seen in the old days.? Which explains a lot..like? chokes fried,? excess? B+? onto rectifiers, tube , rf deck, overloaded caps, etc.?
The only fix I can see? working is a HD spark gap across the? choke terminals.?
Jim? ?VE7RF
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C-L-C, bad news
? On paper, the? C-L-C is a superb output filter? for any B+ supply, reducing ripple to low levels.? ?Even with low value caps on either side, and a? ?2-4H? choke used,? it works superb.? ? I tried the? config and the theory works. Ok, here's the problem.? ?IF the? B+? arcs to chassis, in? the RF deck,? ?or say from? anode to grounded grid, etc, then a huge fault current results.. only limited by the 50 ohm glitch Resistor.? ?2 msecs later, the? HV fuse, located just in board of the? glitch R, opens up.?? Fault current goes from 100 / 134 amps? ( depending on? ?5700 / 7700? config).? ? ?down to? zero....in <? 2msecs flat.? ? The? resulting EMF? from the? 4 H / 127 lb Dahl choke is nothing short? of insane.? ?Like? 10-14 kv.? It also oscillates back and forth in polarity, which charges up / discharges the caps? on either side of the? choke.? ?Current? going into both caps is also insane.? It like ringing a gong..and takes a several seconds to settle down.?? Same deal? ? if a 'normal'? ?L-C? config used, like seen in the old days.? Which explains a lot..like? chokes fried,? excess? B+? onto rectifiers, tube , rf deck, overloaded caps, etc.? The only fix I can see? working is a HD spark gap across the? choke terminals.? Jim? ?VE7RF |
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Re: Plate Transformer
Phil Heaton - N4BBQ
¿ªÔÆÌåÓýNot Bryan here, but KF8OD has some great transformer winding info on his QSL.net page. I used his info in building my own. And although it was fun, and I cranked out a decent product, when it gets down to it, its about as cheap to just buy one like Carl suggested. ? 73, Phil ? From: jim.thom@... [ham_amplifiers]
Sent: Monday, November 19, 2018 10:30 To: ham_amplifiers@... Subject: Re: [ham_amplifiers] Plate Transformer ? ? Bryan ? What's the procedure for? re-winding a plate xfmr ??? ?Is the primary? wound 1st, with the sec on top ?? ?What typ goes on the oem xmfrs,? shorted? pri / sec turns, or short from pri to sec... or pri? to casing or sec to casing ?? ? What's? typ used, a custom jig that rotates on it;s axis, and miles of fish tape and wire ?? ?I have never seen it done.? ? Jim? VE7RF ? |
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Re: Plate Transformer
Bryan
What's the procedure for? re-winding a plate xfmr ??? ?Is the primary? wound 1st, with the sec on top ?? ?What typ goes on the oem xmfrs,? shorted? pri / sec turns, or short from pri to sec... or pri? to casing or sec to casing ?? What's? typ used, a custom jig that rotates on it;s axis, and miles of fish tape and wire ?? ?I have never seen it done.? Jim? VE7RF |
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Re: Plate Transformer
Jim, I'm not the one w/ the transformer issue. I advocate ?the?OP rewind what he has. That eliminates the cost of shipping heavy iron. And, rewinding is quick, EASY & dirt cheep. The next best choice is Lou's suggestion -- a HK?SB-22x/HL-2200 HV xfmr, for a bit higher HV (and better IMD3). I would't waste my time/money on anything less. vy 73, Bryan WA7PRC ____________________________________________________________ Subject: Re: Plate Transformer From: ?Jim VE7RF Date: Sat Nov 17, 2018 8:04 am Nov 16 10:25 AM ##? Bryan,? how did u manage to kill? the? L4PS? drake? xfmr ?? I have been beating on one? since I bought it new in 1977.? What was the failure mechanism,? did the sec go open,? or shorted sec turns or what , or something else. Jim? VE7RF |
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Re: Plate Transformer
¿ªÔÆÌåÓý? Joe ¨C W7RKN ? From: ham_amplifiers@... [mailto:ham_amplifiers@...] ? Today at 8:12 AM ? ? ##? which drake site? are u talking? about.? ? The? WB4HFN? site ?? ? or something else?? ? Jim? ?VE7RF |
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Re: Plate Transformer
¿ªÔÆÌåÓýAgain, I would strongly recommend you join the DrakeRadios group for all your L4/L4B needs and questions. ? Joe ¨C W7RKN ? From: ham_amplifiers@... [mailto:ham_amplifiers@...] ? Nov 16 10:25 AM ##? Bryan,? how did u manage to kill? the? L4PS? drake? xfmr ?? ?I have been beating on one? since I bought it new in 1977.? ?What was the failure mechanism,? did the? sec? go open,? or shorted sec turns or what , or something else. ##? What gauge wire was used on the oem? xfmr ?? Jim? ?VE7RF |
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Re: Plate Transformer
<Bryan Swadener Nov 16 10:25 AM <The amplifier in question isn't a Heath SB-220. It's a Drake L4/L7, with a separate HV <PS. <Bryan WA7PRC ##? Bryan,? how did u manage to kill? the? L4PS? drake? xfmr ?? ?I have been beating on one? since I bought it new in 1977.? ?What was the failure mechanism,? did the? sec? go open,? or shorted sec turns or what , or something else. ##? What gauge wire was used on the oem? xfmr ?? Jim? ?VE7RF |
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Re: Plate Transformer
Rewinding your transformer yourself is the BEST plan. Cost is about 1/3 paying someone to rewind it or replacing it (plus the cost of shipping heavy iron). And, it's quick, easy, CHEEPest, and fun..?I keep mentioning it because... it's true. The amplifier in question isn't a Heath SB-220. It's a Drake L4/L7, with a separate HV PS. Bryan WA7PRC |
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Re: Plate Transformer
BOTH of the ones I mentioned are SUITABLE if they fit and there is no rule that the SB-220 has to run at 1200-1300W out. A little more or less cant be heard.
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OTOH the one you suggested is for the senior series amps that are capable of ~ 2200W. First it wont fit; plus serious overkill even mounted externally; and way expensive. Another little problem is that it is not directly compatible with the SB-220 PS circuit OTOH Part 406-1572 was designed for a 1200W output amp and is 23# and only $142.60 which is the same as you spent not counting labor preparing and the actual winding. That is not something most hams want to do even tho you keep mentioning it on other forums over and over. Part 146-1248-1 is used for both the AL-800 and 800H, is 33# and costs $247. Others can decide which is the better deal. Carl ----- Original Message -----
From: Bryan Swadener bswadener@... [ham_amplifiers] To: ham_amplifiers@... Sent: Thursday, November 15, 2018 8:43 AM Subject: Re: [ham_amplifiers] Plate Transformer The only Ameritron transformer that's suitable for a pair of 3-500Zs is the #406-1418-1D (2570V/0.8A) unit. At $403, it's nearly 3X the cost of rewinding a DOA xfmr. My total cost to rewind a ¡Ý 3KVA xfmr was about $140. It was easy & fun, too. Bryan WA7PRC ________________________________________________________________________ Subject: Re: Plate Transformer From: Carl Date: Wed Nov 14, 2018 6:43 pm ((PST)) Has anyone looked at the AL-572 or AL 800 transformer as an alternative? Ones from Ameritron tend to be far cheaper than others. Carl ----- Original Message ----- From: Lou W1QJ To: ham_amplifiers@... Sent: Sunday, November 11, 2018 3:44 PM Subject: Re: [ham_amplifiers] Plate Transformer Gary, it¡¯s probably cheaper to retrofit an SB220 transformer. I¡¯ve done it several times and have a schematic detailing the simple conversion. On Sunday, November 11, 2018, [email protected] wrote: Hello, Does anyone know of a source to have a plate transformer in a L-4/L-7 power supply rewound? Thanks & 73, Garry - K4OR --- This email has been checked for viruses by AVG. |
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Re: Plate Transformer
The only Ameritron transformer that's suitable for a pair of 3-500Zs is the #406-1418-1D (2570V/0.8A) unit. At $403, it's nearly 3X the cost of rewinding a DOA xfmr. My total cost to rewind a ¡Ý 3KVA xfmr was about $140. It was easy & fun, too. Bryan WA7PRC ________________________________________________________________________ Subject: Re: Plate Transformer From: Carl Date: Wed Nov 14, 2018 6:43 pm ((PST)) Has anyone looked at the AL-572 or AL 800 transformer as an alternative? Ones from Ameritron tend to be far cheaper than others. Carl ----- Original Message ----- From: Lou W1QJ Sent: Sunday, November 11, 2018 3:44 PM Subject: Re: [ham_amplifiers] Plate Transformer Gary, it¡¯s probably cheaper to retrofit an SB220 transformer.? I¡¯ve done it? several times and have a schematic detailing the simple conversion. On Sunday, November 11, 2018, k4or@...?wrote: Hello, Does anyone know of a source to have a plate transformer in a L-4/L-7 power supply rewound? Thanks & 73, Garry - K4OR |
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Re: Plate Transformer
Has anyone looked at the AL-572 or AL 800 transformer as an alternative? Ones from Ameritron tend to be far cheaper than others.
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Carl ----- Original Message -----
From: Gudguyham@... [ham_amplifiers] To: ham_amplifiers@... Cc: ham_amplifiers@... Sent: Sunday, November 11, 2018 3:44 PM Subject: Re: [ham_amplifiers] Plate Transformer Gary, it¡¯s probably cheaper to retrofit an SB220 transformer. I¡¯ve done it several times and have a schematic detailing the simple conversion. Sent from AOL Mobile Mail Get the new AOL app: mail.mobile.aol.com On Sunday, November 11, 2018, k4or@... [ham_amplifiers] <ham_amplifiers@...> wrote: Hello, Does anyone know of a source to have a plate transformer in a L-4/L-7 power supply rewound? Thanks & 73, Garry - K4OR --- This email has been checked for viruses by AVG. |
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Re: 40 and 50 A SSR
<Jeff Blaine Nov 13 4:45 PM <A SSR is a great gadget to use when wanting to avoid relay arcing.? The SSR switches at the zero voltage <point and will survive when a relay may die fast - i found that out when using a capacitor in a motor lead <as a form of speed control.? After replacing a couple of relays and spending a lot of time messing with <snubber solutions that did not do a very good job, tried the SSR and it was a winner. <What SSR is not good at - high surge conditions.? I've used SSR as on the mains switch to amps before <and in the event of a glitch even huge "400A" rated one are not reliable.? For those, a big contactor-type <relay was the bullet proof solution. ###? I looked at? SSR's in depth, years ago.? I didn't even see? any surge ratings anywhere on the few spec sheets I had at the time.? ?I did look at the? 40 +? 70A? variety.? What you want, IF? you use them, is a? SSR that has a ZERO? VOLTAGE? cross? on TURN ON............and a? ?ZERO? CURRENT cross? on SHUT? DOWN.? ##? Most are just? zero voltage? turn on..and off.? ?Fine for most ham applications, since the B+? supply is typ turned off with? amp in stand by mode anyway.? ?Don't be running full bore? CXR? /? FM? /? ?data? modes, and reach over and? shut the supply off..via the SSR....? the back? emf? ?from the primary? of the plate xfmr will fry the? SSR's.... and? some heavy duty MOV's? are required on the pri.?? ##? My problem with the SSR's? ?is they all required a huge heatsink.? ?Checked my notes? just now and the P+B? types? required? one? square foot of heat sink for EACH? ?SSR.? ? And? TWO? SSR's? were required, one for? each leg of the? 240.? ?And that doesn't mean? placing them an inch apart on the chassis either.? There was also an? issue with leakage across them.? Like? typ? 10? microamps or more.? ? My electrician ham buddy here in town said that in Canada, all these SSR's? had to have a supplemental? ?fuse? / breaker in front of them.? In the P+B catalog at the time,? they showed? typ applications for? ?SSR's.? The example they used depicted a? 150 HP? electric motor, run on 600 volt? 3 phase...... and the start up current was TRIPLE the running loaded current.? ?The ensuing mess of? SSR's? was something else to behold on their diagram.? ?P+B? sez? they could be wired in series for more voltage....? and paralleled..for more? current..and also both series / parallel.? ? ?In the above case of the? 150 HP motor, run on? 600 V? 3 phase.. they used a mess of? SSR's in parallel and series to do the job.? ? I think the biggest? SSR they had in the catalog at the time were either 70A..or? 110 Amp.? ?I looked at their? wiring diagram, and all the various potential leakage paths... and the? series / parallel mess..for each phase...(? 6-9? per phase) .. and thought to myself....? ?what a bitch to trouble shoot, if just any one of the 18-27? x? SSR's? ?were to crap out.? ? ?Dunno if they fail? open / shorted? or either.? ?Then all the? control circuitry? to? switch on /off..simultaneously,..all? ?18-27 of em.?? ##? In the end,? I ended up using a simple? DPST? contactor? for that? ?B+? project at the time.? ?I have also paralleled? DPST? and also esp? 3PDT? ?contactors for more current? handling capability.? ?In those? 2 x cases,? a paralleled 3PDT? contactor is used in each of the hot legs of the incoming 240 line.? ?If? no room inside the box,? then the contactors? are located in an external? box, like a small electrical box, like a 8x8x4? or? 10x10x6? type... with a control cable to run it.? ##? 135 A? ?3 pole? contactors, with? 220 v solenoids? (? will run on anything from 208-240).. are? still available, new in box, for $50, from one of the surplus electrical dealers in usa.? ? ?You can see pix of em on the? 3x6 pix page..under my callsign.? 3 were used, and each had all 3 contacts paralleled? ?with simple? 1x1? angle aluminum.? One contactor in each leg of the 240 line.? 3rd one did the step start.? ##? I also bought a bunch of? 3PDT? contactors on sale years ago? from sson, made by prestolite.? ?Rated at? 300A per pole.? The in /outs on all 6 x connections all? came with? built in? cu buss? bar...so the contactor is simply bolted right to?one of the? 230 V inputs on the big dahl xfmr... since the dahl uses? 3/8" bolts.? ?The cu buss bar uses? 5/16"? ?holes..so drilled one out to? 3/8".?? ##? One of the commercial? ham? ?tube? amps, did use a pair of? SSR's on the input, with a zero V cross..and? no step start.? ?The? zero V cross? allows for? 8.3 Msec? ?ramp on time.? Think it was a ten tec, but not sure.? Jim? ?VE7RF? |
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Re: 40 and 50 A SSR
¿ªÔÆÌåÓýA SSR is a great gadget to use when wanting to avoid relay arcing.? The SSR switches at the zero voltage point and will survive when a relay may die fast - i found that out when using a capacitor in a motor lead as a form of speed control.? After replacing a couple of relays and spending a lot of time messing with snubber solutions that did not do a very good job, tried the SSR and it was a winner. What SSR is not good at - high surge conditions.? I've used SSR
as on the mains switch to amps before and in the event of a glitch
even huge "400A" rated one are not reliable.? For those, a big
contactor-type relay was the bullet proof solution. 73/jeff/ac0c alpha-charlie-zero-charlie On 13-Nov-18 4:56 PM, n2lym
n2lym@... [ham_amplifiers] wrote:
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Re: Plate Transformer
Rewinding is easy and CHEAP... My first rewind was HV --> LV for a 13.8V/30A PS that I built in the 80s and still use today. My latest rewind was LV --> HV for a 3.5-4KV/1.5A amplifier PS. Information is everywhere. Manfred XQ6FOD has good info about magnetics (http://ludens.cl/Electron/Magnet.html) and practical transformer re/winding info (http://ludens.cl/Electron/trafos/trafos.html). Materials are everywhere. I found 10# of 18 AWG polyimide (Kapton?) coated wire for about $40 and NMN333 "paper" for about $100. I had enough for at least TWO transformers. A local transformer/motor shop vacuum-impregnated the rewound xmfr free-gratis. Bottom line: I wound-up w/ a xfmr that can supply > 3KVA (at 100% D/C) for 25% of the cost of a 600VA xfmr. vy 73, Bryan WA7PRC -------------------------------------------- From: Lou W1QJ Subject: [ham_amplifiers] Plate Transformer Date: Mon Nov 12, 2018 9:02 am Gary Brown is shutting down, his business is for sale. -------------------------------------------- From: Roy KO4LM: Subject: [ham_amplifiers] Plate Transformer Date: Sunday, November 11, 2018, 2:56 PM try Transformer Rewind Service - Gary Brown WZ1M? 478 Forest Avenue Orono, ME 04473 Roy KO4LM -------------------------------------------- Hello, Does anyone know of a source to have a plate transformer in a L-4/L-7 power supply rewound? Thanks & 73,Garry - K4OR |