Re: [Drakelist] L-7 blew circuit breaker when turned on, what's up?
It looks like we have it working now, please disregard prior message. 73, Bill --- On Sat, 6/5/10, Bill Dzurilla wrote: > From: Bill Dzurilla > Subject: L-7 blew circuit breaker when turned on, what's up? > To: drakelist@zerobeat.net > Date: Saturday, June 5, 2010, 11:44 AM > Hi, > > I have arrived in Europe and the L-7 seems to have made it > without damage, at least no visual damage. > > The amp was wired for 220v when I had it in the USA. > Upon arrival here, I switched the USA AC plug for a European > plug. But as soon as I turned on the amp, the house > circuit breaker blew. My first thought was that I had > incorrectly installed the plug, but I have checked with an > ohm meter and no sign of a short. There is infinite > resistance between each pin of the AC plug and ground, and > there is infinite resistance between each of the two pins > when the amp's on/off switch is turned off. When > switched on, resistance between the two pins is about 1 ohm, > which I believe is as it should be. > > There should be no polarity issue between the 2 pins, > correct? > > Any thoughts on what might be wrong and how to test it > safely before applying AC power again? > > 73, > Bill NZ5N/OM9ACA > > > > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] L-7 blew circuit breaker when turned on, what's up?
Hi, I have arrived in Europe and the L-7 seems to have made it without damage, at least no visual damage. The amp was wired for 220v when I had it in the USA. Upon arrival here, I switched the USA AC plug for a European plug. But as soon as I turned on the amp, the house circuit breaker blew. My first thought was that I had incorrectly installed the plug, but I have checked with an ohm meter and no sign of a short. There is infinite resistance between each pin of the AC plug and ground, and there is infinite resistance between each of the two pins when the amp's on/off switch is turned off. When switched on, resistance between the two pins is about 1 ohm, which I believe is as it should be. There should be no polarity issue between the 2 pins, correct? Any thoughts on what might be wrong and how to test it safely before applying AC power again? 73, Bill NZ5N/OM9ACA ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Repacement for R12 fuse resistor on L-4B and L-7 power supply?
OK, a local ham kindly gave me a spare glitch resistor as a replacement for R12, and the Drake has been repaired, tested, and then packed for the trip. The homebrew 5m amp has been reconnected to its internal HV p/s, tested, and then packed. I may never find out what caused R12 to blow, because I'm disinclined to mess with the power supply switch again. Sure would be nice to get higher voltage on the 6m amp, because I'm sure the 3-500Z would give me double the current 350w output with a better p/s, but c'est la vie. Thanks to all who responded, both on the forum and offline. 73, Bill --- On Mon, 5/31/10, Bill Dzurilla wrote: > From: Bill Dzurilla > Subject: Repacement for R12 fuse resistor on L-4B and L-7 power supply? > To: drakelist@zerobeat.net > Date: Monday, May 31, 2010, 3:04 PM > Well, I have determined that the > cause of my power supply problem is R12, the .82 ohm 2 watt > resistor on the B+ output of the power supply. It is > visibly damaged. > > I have searched this list and elsewhere and it seems there > is a split of opinion on whether to replace R12 with a > similar resistor. Rich Measures and others have > suggested using instead a 10 ohm 10 watt wirewound > resistor. > > I am leaving for Europe on Wednesday and need to find a > replacement quickly. Radio Shack has a 10 ohm 10 watt > wirewound that I can get locally if that will work. > Don't think I have time for any mail order. > > What do you think, will the Radio Shack one work? > > 73, Bill NZ5N > > > > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Repacement for R12 fuse resistor on L-4B and L-7 power supply?
Well, I have determined that the cause of my power supply problem is R12, the .82 ohm 2 watt resistor on the B+ output of the power supply. It is visibly damaged. I have searched this list and elsewhere and it seems there is a split of opinion on whether to replace R12 with a similar resistor. Rich Measures and others have suggested using instead a 10 ohm 10 watt wirewound resistor. I am leaving for Europe on Wednesday and need to find a replacement quickly. Radio Shack has a 10 ohm 10 watt wirewound that I can get locally if that will work. Don't think I have time for any mail order. What do you think, will the Radio Shack one work? 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] L-4B and L-7 power supply: Amp plate voltage drops to zero when PTT pressed, help please
Hello, As you may know from my prior post, I have a homebrew 6m 3-500Z amp that I am trying to get to work with a Drake L-7 power supply, so far without success. The amp has an internal power supply, with the HV disconnected. I have the B+ of Drake p/s connected directly to the same spot where the B+ from the internal p/s had been connected, and I have the B- of the the Drake p/s connected to chassis ground. Using a high voltage probe, today I verified that the Drake p/s is providing 2800 vdc directly on the plate of the 3-500Z, when everything is turned on but the PTT is not engaged. But when the PTT is engaged, even with no drive, plate voltage immediately drops to zero. My first thought was a B+ to B- short, but this would have caused a big bang, and nothing is banging or smoking or doing anything unusual at all. No fuse or circuit breaker pops. When the the PTT is pressed, a DPDT relay closes. One side activates the T/R coaxial relay, and the other side grounds the center tap of the filament transformer via the plate current meter. These are the only things that happen when the PTT is engaged. In the absence of a filament to plate short (which would have self-diagnosed with a bang), I can't imagine any reason why pressing the PTT would cause the plate voltage to drop to zero. Anyone have any idea at all what might be going on? It almost seems like the Drake p/s is shutting itself off when the PTT is engaged, and then turning itself back on when the PTT is released. The Drake p/s does not have any sort of internal shut down mechanism, does it? Thanks for any thoughts and 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Using HV from L-4B and L-7 power supply on another amp
Thanks to Garey and to those who replied off-line to my question about the one ohm resistor. May I trouble you with another question? I have a homebrew 6m 3-500Z amp with similar circuitry to the L-7 and L-4B. Unfortunately, its power supply is not that beefy (2000v) and I don't get full output. So I came up with the idea of trying to connect my L-7 power supply to the other amp. To do this, I disconnected the homebrew amp's internal p/s HV connections (leaving in place the internal p/s's filament, relay, and blower connections) and attempted to connect the Drake p/s. I connected the Drake p/s's HV cable to the homebrew amp's B+ connection, and I connected the Drake p/s's B- connection (pin 6 of the Cinch connector) to ground on the homebrew amp. I also grounded the chassis' together. To turn the Drake p/s on, I jumpered pins 1 and 3 of the Cinch connector. After hooking all this up, I turned everything on and it did not work. There was no RF output at all from the homebrew amp. The plate current meter showed some plate current, but much less than usual. What am I doing wrong? All I can think of is that I'm forgetting to make some connection, or that I have the Drake p/s AC input wired wrong. Jumpering pins 1 and 3 seems to be the equivalent of turning the Power switch to On and turning the CW Tune/SSB switch to SSB, but perhaps I'm reading this wrong or forgetting something. Any thoughts or ideas would be greatly appreciated. 73, Bill NZ5N --- On Sat, 5/29/10, Bill Dzurilla wrote: > From: Bill Dzurilla > Subject: Re: L-4B and L-7 power supply question > To: drakelist@zerobeat.net > Cc: k4...@mindspring.com > Date: Saturday, May 29, 2010, 11:26 AM > Garey, > Thanks for the reply. I still don't get why the > resistor is needed. The ammeter is in series with the > flow of the current, so what does the resistor do? > What would happen if B- went directly to ground? I'm > sure the answer is simple but for some reason it is evading > me. > 73, Bill > > Bill - > > It's just a relatively safer way (low voltage) to measure > current of a > high voltage supply. Any current that goes OUT of the > supply on the > positive end MUST come IN via the negative end, or > vice-versa depending > upon whether you learned your electronics in the military > or civilian > schools! > > Anyway, the resistor is near ground, (unless it opens!,) > and so > connecting it to a panel meter is much safer than having > the meter > connect across a shunt resistor somewhere up in the HV area > of the supply. > > 73, Garey - K4OAH > > > --- On Sat, 5/29/10, Bill Dzurilla > wrote: > > > From: Bill Dzurilla > > Subject: L-4B and L-7 power supply question > > To: drakelist@zerobeat.net > > Date: Saturday, May 29, 2010, 9:56 AM > > Hi, > > > > The B- of the power supply for the Drake L-4B and L-7 > goes > > to pin 6 of the Cinch connector. Inside the amp, > the > > B- is floated above ground by a one ohm resistor. > The > > one ohm resistor that floats B- above ground is said > to be > > for the purpose of plate current metering. I do not > > quite understand how this resistor is needed for > plate > > current meter accuracy. Could someone please tell > me > > how that works? > > > > I have an L-7 and a homebrew amp that uses a similar > power > > supply. However, in the homebrew amp the B- goes > > directly to ground. I'm trying to understand the > > difference in the configurations. > > > > Thanks and 73, > > Bill NZ5N > > > > > > > > > > > > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] L-4B and L-7 power supply question
Garey, Thanks for the reply. I still don't get why the resistor is needed. The ammeter is in series with the flow of the current, so what does the resistor do? What would happen if B- went directly to ground? I'm sure the answer is simple but for some reason it is evading me. 73, Bill Bill - It's just a relatively safer way (low voltage) to measure current of a high voltage supply. Any current that goes OUT of the supply on the positive end MUST come IN via the negative end, or vice-versa depending upon whether you learned your electronics in the military or civilian schools! Anyway, the resistor is near ground, (unless it opens!,) and so connecting it to a panel meter is much safer than having the meter connect across a shunt resistor somewhere up in the HV area of the supply. 73, Garey - K4OAH --- On Sat, 5/29/10, Bill Dzurilla wrote: > From: Bill Dzurilla > Subject: L-4B and L-7 power supply question > To: drakelist@zerobeat.net > Date: Saturday, May 29, 2010, 9:56 AM > Hi, > > The B- of the power supply for the Drake L-4B and L-7 goes > to pin 6 of the Cinch connector. Inside the amp, the > B- is floated above ground by a one ohm resistor. The > one ohm resistor that floats B- above ground is said to be > for the purpose of plate current metering. I do not > quite understand how this resistor is needed for plate > current meter accuracy. Could someone please tell me > how that works? > > I have an L-7 and a homebrew amp that uses a similar power > supply. However, in the homebrew amp the B- goes > directly to ground. I'm trying to understand the > difference in the configurations. > > Thanks and 73, > Bill NZ5N > > > > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] L-4B and L-7 power supply question
Hi, The B- of the power supply for the Drake L-4B and L-7 goes to pin 6 of the Cinch connector. Inside the amp, the B- is floated above ground by a one ohm resistor. The one ohm resistor that floats B- above ground is said to be for the purpose of plate current metering. I do not quite understand how this resistor is needed for plate current meter accuracy. Could someone please tell me how that works? I have an L-7 and a homebrew amp that uses a similar power supply. However, in the homebrew amp the B- goes directly to ground. I'm trying to understand the difference in the configurations. Thanks and 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Power supply connectors for L-7 and L-4B
Yes, Evan, Millen no. 37001-D, in case anyone else is thinking about building an RF deck using the Drake power supply. It's not cheap ($15 shipped) and some say it is unreliable and even dangerous, but I don't want to change the connector on such a classic amp. The Cinch connector was also expensive ($20 shipped) and quite tough to find. 73, Bill NZ5N --- On Mon, 5/24/10, k9...@aol.com wrote: From: k9...@aol.com Subject: Re: [Drakelist] Power supply connectors for L-7 and L-4B To: billdz@yahoo.com, drakelist@zerobeat.net Date: Monday, May 24, 2010, 8:30 AM Bill, That connector is a standard Millen connector. They are available at RF Parts, Upay (Ebay), and elsewhere. 73, Evan -Original Message----- From: Bill Dzurilla To: drakelist@zerobeat.net Sent: Mon, May 24, 2010 7:15 am Subject: [Drakelist] Power supply connectors for L-7 and L-4B Hello, I have a homebrew 6 meter RF deck using a 3-500Z tube. I was thinking I could power it with my L-7 power supply. The big 8 pin connector appears to be a standard Cinch connector. What about the High Voltage connector, what is that? And where could such a connector be purchased? 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Power supply connectors for L-7 and L-4B
Hello, I have a homebrew 6 meter RF deck using a 3-500Z tube. I was thinking I could power it with my L-7 power supply. The big 8 pin connector appears to be a standard Cinch connector. What about the High Voltage connector, what is that? And where could such a connector be purchased? 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video
Thanks for the reminder about the cooling, Evan. The source of the arc is difficult to see in the video, but if you look through the plastic bubble that forms the back side of the plate current meter, you can see the source of the arc, in the Plate tuning capacitor. 73, Bill --- On Wed, 5/19/10, k9...@aol.com wrote: From: k9...@aol.com Subject: Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video To: w4...@aol.com, billdz@yahoo.com, drakelist@zerobeat.net Date: Wednesday, May 19, 2010, 5:09 PM Caution is in order when testing the amp for any significant period of time. With the top off, the base of the tubes will not get adequate cooling. Even though there are slots on the bottom side of the cabinet, with the top off most of the air to cool the tubes will come from above with little from below. Seeing the source of the arc is difficult in the video, it almost seems like it is coming from the "green PC board" type of capacitor. Hard to tell. 73, Evan -Original Message- From: w4...@aol.com To: billdz@yahoo.com; drakelist@zerobeat.net Sent: Wed, May 19, 2010 3:20 pm Subject: Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video In a message dated 5/18/2010 10:38:27 P.M. Eastern Daylight Time, billdz@yahoo.com writes: http://www.youtube.com/watch?v=iJRyNQnkEWA I notice 2 things: The tube nearest the transformer is displaying a red plate before the tube nearest the side panel and it appears to be more than the tube toward the panel side. I also notice what appears to be a small black dot near the first full turn of the plate coil. This is not on the ceramic as far as I can tell and is not one of the rivets holding the ceramic. It seems to disappear a split second before the arc is heard on the sound track. I don't have the cover off my L-7 so I can't duplicate what I am seeing bit that might be a clue to the problem. Good luck and please let us know what you find. 73, John, W4AWM ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video
Thanks, John. I noticed the black dot as well and it drove me crazy trying to figure it out. After many attempts to duplicate, it turned out to be the rotor on the Load cap. It disappears a moment before the arc because I was turning that control to the left at the time of the arc. That is what led me to believe, as explained by W8JI and others, that the arcing was being caused by inadequate loading. When I tried again and left the Load control on 5, there was no arcing. I had not noticed the difference between the 2 tubes until you mentioned it. Possibly just a result of the camera angle. If not, what could it mean? 73, Bill NZ5N --- On Wed, 5/19/10, w4...@aol.com wrote: From: w4...@aol.com Subject: Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video To: billdz@yahoo.com, drakelist@zerobeat.net Date: Wednesday, May 19, 2010, 3:20 PM In a message dated 5/18/2010 10:38:27 P.M. Eastern Daylight Time, billdz@yahoo.com writes: http://www.youtube.com/watch?v=iJRyNQnkEWA I notice 2 things: The tube nearest the transformer is displaying a red plate before the tube nearest the side panel and it appears to be more than the tube toward the panel side. I also notice what appears to be a small black dot near the first full turn of the plate coil. This is not on the ceramic as far as I can tell and is not one of the rivets holding the ceramic. It seems to disappear a split second before the arc is heard on the sound track. I don't have the cover off my L-7 so I can't duplicate what I am seeing bit that might be a clue to the problem. Good luck and please let us know what you find. 73, John, W4AWM ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video
Many thanks to all who watched the video and emailed me with ideas. I have watched it 50 times and I'm now convinced that the arc occurred in the plate cap stator that has the white graffiti-like traces, as described in a prior post. The flashes on the coil are just reflections. If you look carefully through the plastic bubble on back of the plate current meter, you can see the arc originating in the plate tuning capacitor. Suggested fixes have included: * replacing the mica caps mounted underneath the rear wafer of the bandswitch, * replacing the plate blocking capacitors, * polishing or totally removing the stator with the white traces, * Carl's suggestion below to try a piece of insulation between the coil and the cap. Have not yet tried any of these suggestions, but please keep the ideas coming. 73, Bill NZ5N --- On Tue, 5/18/10, Bill Dzurilla wrote: > From: Bill Dzurilla > Subject: Re: Drake L-7 arc - plate capacitor issue? Now with video > To: drakelist@zerobeat.net > Date: Tuesday, May 18, 2010, 10:36 PM > Thanks to all who responded on and > off line. I removed the cover and tried it > again. Rig was connected to a Heathkit Cantenna dummy > load. As suggested by several, I set the Load control > to 5 at the start, to prevent under-coupling. I made a > video of the procedure and, as you can see at: > http://www.youtube.com/watch?v=iJRyNQnkEWA > There was arcing again. The arc occurs near the end > of the video clip, at the 1:18 mark. You can see it on > the first 2 turns of the coil that is on top of the Plate > capacitor. Not sure if this is a reflection or if the > coil itself was arcing. I did not see any arcing from > the capacitor. > > Not sure how visible it is on YouTube, but I have watched > this several times in slow motion. You can see a bit > of the rotor of the Load capacitor on the left side of the > screen, and also a bit of the output meter. At least in > slo-mo, you can see output going up as I start to turn the > Load cap to the left, then the tubes start to redden and the > arc occurs. > > If the turning of the Load cap to the left resulted in > under-coupling and caused the arc, I'm not sure how to > proceed, because output was very low with the Load cap set > at 5. > > Comments, ideas, advice? > > 73, Bill NZ5N > > issue? > > From: "Jim Shorney" > > Subject: Re: [Drakelist] Drake L-7 arc - plate > capacitor > > issue? > > To: "drakelist@zerobeat.net" > > > > Message-ID: <20100518034250.eab1b31b...@mail01.inebraska.com> > > Content-Type: text/plain; charset="iso-8859-1" > > > > All the amp gurus must still be recovering from > Dayton. > > Bill, you didn't > > mention if you were testing with an antenna or a > dummy > > load. > > > > 73 > > > > -Jim > > > > On Sun, 16 May 2010 09:19:35 -0700 (PDT), Bill > Dzurilla > > wrote: > > > > >I opened up the amp and everything looks OK, > except for > > one of the 25 or so stators on the plate tuning > capacitor > > has graffiti-like white traces on it. I suspect > this > > is the source of the 80m arcing, as the rotor does not > the > > spot with the traces on 40m and up. I have not > tried > > the amp on 160m, but if my theory is correct it would > arc on > > 160 as well as 80. > > > > > >The capacitor plates are not dented or deformed in > any > > way. > > > > > >So, do you think this is the source of the > > problem? If yes, is there any fix? > > > > > >73, Bill NZ5N > > > > > >--- On Fri, 5/14/10, Bill Dzurilla > > wrote: > > > > > >> From: Bill Dzurilla > > >> Subject: Drake L-7 arc and loose band switch > knob > > >> To: drakelist@zerobeat.net > > >> Date: Friday, May 14, 2010, 10:35 PM > > >> Hi, > > >> > > >> I recently acquired an L-7 amp and I tried it > out > > >> today. I used my Pro II as the exciter and > > an amp > > >> keyer. > > >> > > >> There seems to be some problem on 80, > > unfortunately. > > >> On all bands, I started with 20 watts drive > and > > slowly > > >> increased the drive while tuning for max > > output. When > > >> I got up to about 600 watts out on 80, I > heard and > > saw > > >> through the meter a blue arc. This > happened > > twice on > > >> 80, and I did not want to try it again. > Not > > sure what > > >> this means, no arc on any other band. Any > > thoughts on > > >> what might be wrong on 80? > > >> > > >> 73, Bill NZ5N > > > > > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake L-7 arc - plate capacitor issue? Now with video
Thanks to all who responded on and off line. I removed the cover and tried it again. Rig was connected to a Heathkit Cantenna dummy load. As suggested by several, I set the Load control to 5 at the start, to prevent under-coupling. I made a video of the procedure and, as you can see at: http://www.youtube.com/watch?v=iJRyNQnkEWA There was arcing again. The arc occurs near the end of the video clip, at the 1:18 mark. You can see it on the first 2 turns of the coil that is on top of the Plate capacitor. Not sure if this is a reflection or if the coil itself was arcing. I did not see any arcing from the capacitor. Not sure how visible it is on YouTube, but I have watched this several times in slow motion. You can see a bit of the rotor of the Load capacitor on the left side of the screen, and also a bit of the output meter. At least in slo-mo, you can see output going up as I start to turn the Load cap to the left, then the tubes start to redden and the arc occurs. If the turning of the Load cap to the left resulted in under-coupling and caused the arc, I'm not sure how to proceed, because output was very low with the Load cap set at 5. Comments, ideas, advice? 73, Bill NZ5N > issue? > From: "Jim Shorney" > Subject: Re: [Drakelist] Drake L-7 arc - plate capacitor > issue? > To: "drakelist@zerobeat.net" > > Message-ID: <20100518034250.eab1b31b...@mail01.inebraska.com> > Content-Type: text/plain; charset="iso-8859-1" > > All the amp gurus must still be recovering from Dayton. > Bill, you didn't > mention if you were testing with an antenna or a dummy > load. > > 73 > > -Jim > > On Sun, 16 May 2010 09:19:35 -0700 (PDT), Bill Dzurilla > wrote: > > >I opened up the amp and everything looks OK, except for > one of the 25 or so stators on the plate tuning capacitor > has graffiti-like white traces on it. I suspect this > is the source of the 80m arcing, as the rotor does not the > spot with the traces on 40m and up. I have not tried > the amp on 160m, but if my theory is correct it would arc on > 160 as well as 80. > > > >The capacitor plates are not dented or deformed in any > way. > > > >So, do you think this is the source of the > problem? If yes, is there any fix? > > > >73, Bill NZ5N > > > >--- On Fri, 5/14/10, Bill Dzurilla > wrote: > > > >> From: Bill Dzurilla > >> Subject: Drake L-7 arc and loose band switch knob > >> To: drakelist@zerobeat.net > >> Date: Friday, May 14, 2010, 10:35 PM > >> Hi, > >> > >> I recently acquired an L-7 amp and I tried it out > >> today. I used my Pro II as the exciter and > an amp > >> keyer. > >> > >> There seems to be some problem on 80, > unfortunately. > >> On all bands, I started with 20 watts drive and > slowly > >> increased the drive while tuning for max > output. When > >> I got up to about 600 watts out on 80, I heard and > saw > >> through the meter a blue arc. This happened > twice on > >> 80, and I did not want to try it again. Not > sure what > >> this means, no arc on any other band. Any > thoughts on > >> what might be wrong on 80? > >> > >> 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake L-7 arc - plate capacitor issue?
Jim, The arc occurred with a dummy load, so the antenna system is not to blame. 73, Bill > From: "Jim Shorney" > Subject: Re: [Drakelist] Drake L-7 arc - plate capacitor > issue? > To: "drakelist@zerobeat.net" > > Message-ID: <20100518034250.eab1b31b...@mail01.inebraska.com> > Content-Type: text/plain; charset="iso-8859-1" > > All the amp gurus must still be recovering from Dayton. > Bill, you didn't > mention if you were testing with an antenna or a dummy > load. > > 73 > > -Jim ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake L-7 arc - plate capacitor issue?
I opened up the amp and everything looks OK, except for one of the 25 or so stators on the plate tuning capacitor has graffiti-like white traces on it. I suspect this is the source of the 80m arcing, as the rotor does not the spot with the traces on 40m and up. I have not tried the amp on 160m, but if my theory is correct it would arc on 160 as well as 80. The capacitor plates are not dented or deformed in any way. So, do you think this is the source of the problem? If yes, is there any fix? 73, Bill NZ5N --- On Fri, 5/14/10, Bill Dzurilla wrote: > From: Bill Dzurilla > Subject: Drake L-7 arc and loose band switch knob > To: drakelist@zerobeat.net > Date: Friday, May 14, 2010, 10:35 PM > Hi, > > I recently acquired an L-7 amp and I tried it out > today. I used my Pro II as the exciter and an amp > keyer. > > There seems to be some problem on 80, unfortunately. > On all bands, I started with 20 watts drive and slowly > increased the drive while tuning for max output. When > I got up to about 600 watts out on 80, I heard and saw > through the meter a blue arc. This happened twice on > 80, and I did not want to try it again. Not sure what > this means, no arc on any other band. Any thoughts on > what might be wrong on 80? > > 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake L-7 arc and loose band switch knob
Hi, I recently acquired an L-7 amp and I tried it out today. I used my Pro II as the exciter and an amp keyer. I got 1250 watts out into a dummy load on 40, 20 and 15, and 1000 watts out on 10. My understanding from a Google search is that this is about right, as the power supply is not beefy enough to push it to the 1500w legal limit. However, I did see some claims of this amp obtaining full legal limit, is this real with the stock p/s? There seems to be some problem on 80, unfortunately. On all bands, I started with 20 watts drive and slowly increased the drive while tuning for max output. When I got up to about 600 watts out on 80, I heard and saw through the meter a blue arc. This happened twice on 80, and I did not want to try it again. Not sure what this means, no arc on any other band. Any thoughts on what might be wrong on 80? I have not yet tried 160 or any of the WARC bands. Only other issue observed is that the band switch knob is a little loose. I tightened it as best I could but it still shifts a bit. Is this normal for an amp of this age, and is there any fix? Any thoughts, particularly on the 80m issue, would be appreciated. 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake L-7 and L-4B vs. Swan Mark II?
Hi, What are the primary differences between these Drake and Swan amps? Both are 2-piece with a pair of 3-500 tubes. I suppose the Drake has higher build quality, as the market price for the Drakes is substantially higher. 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] L-7 amp soft start?
Anyone know where to find a soft start for the L-7? Jeff at Harbach told me his L-4B soft start does not work on the L-7, and his universal soft start does not work on either the L-7 or the L-4B. 73, Bill NZ5N ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
