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Author Topic: What AM tower is this (Paul G. Thompson or anyone?) Matthew Bailey Master Film Handler Posts: 461 From: Port Arthur,TX Registered: Sep 2000 posted 10-15-2003 09:43 PM                     From the color of the picture,I think you ought to paint that RCA transmitter Christie blue & green.  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 10-15-2003 11:22 PM                     Phil, I already have some , from the days I was out of a booth and did some DJ work at small parties to get some $$ most of the gear is long gone but still have a set of big speakers (biamping required tho)taking space. and I just finished the weird math to find out core, wire sizes and coil turns for output transformers for a class AB1 amp using 4-65A's and another using 3CX*ahem* tubes , I think something is wrong on them, because I ended with a xformer that's 6"x 2" in size.. it seems just.. too small. (the impedance, voltage and turns ratio came out ok for them tho..)and yes.. I know the 4-65A is a tetrode and I mentioned I'm looking for something with transmitter triodes.but heh.. it was part of the fun Matthew,if you folow that link Mark posted some pages ago here in this topic and keep following the links on those pages you'll find a transmitter with the colors you mentioned I remember seeing a green transmitter in one of those pages and it was either an RCA or a GE.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 10-16-2003 01:37 AM                  If your planning on using those 65kw PP tubes... you will not only need a lot bigger speaker system, but also different neighbors... >>> Phil  |  IP: Logged William Hooper Phenomenal Film Handler Posts: 1879 From: Mobile, AL USA Registered: Jun 99 posted 10-16-2003 02:19 AM                        I think you should pull the front plastic panel off a Coke machine, glue it on the cabinet door, cut a slot in it, & mount the external organs of a bill acceptor over that.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 10-16-2003 02:43 AM                     (I know it is childish, but I just could not resist.)  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 10-16-2003 06:31 AM                  ???? Me thinks someone has been smokin' some of that I-30 stuff... >>> Phil  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 10-16-2003 11:29 AM                     Phil ,the 3CX ***** I'm thinking about isn't one of the big tubes it's a wee compared to most of the 3CX's you have seen , actual code is 3CX300A1, a triode designed for audio and was made by Svetlana only ( buh...)Already called the places I know that still deals with tubes and none of them have the tube or head about it. and Svetlana seems to be gone then find a quad of them will be difficult ( and pricey). The 4-65A only one place deals with it but they didn't have the price for it but told me that it's not cheap, ah well. My speakers are all rotting away and I won't mind if they blown away with the amp..my neigbors are noisy at tiems and we all have out share along the week to bring the house down  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 10-16-2003 02:43 PM                     Phil, I had a reasonable suspicion my last post would blow some minds. I wonder what Josh will reply with? Luciano, I don't think the 833A tubes would sound all that great in a class "B" bias situation. The transition from one tube to the outer would not be that great. Class AB1 might be better or just plain class A. But I doubt you could get the balls out of it under those circumstances. However, it'll probably do a great job of shaking the neighbor's windows....and running up your power bill. Between the power transformer, filament transformer, fixed bias transformer and output transformer, you might have something that weighs about 500 lbs.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 10-16-2003 03:47 PM                  Paul, it wasn't "other" minds that I thought was blown.... While the xmfr iron would certainly be impressive, think about the size of the speaker magnet! Whoo Wee! Luciano, I looked up the 3CX300A1...very interesting tube. Cool audio amp here Some more app notes here >>> Phil  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 10-16-2003 06:53 PM                     Paul, class A (SE or PP) and AB are my kind of thing.class B has it's problems and advantages, there are people that likes class B amps, but I'm more into the A (ouch! hot hot hot! )but the manuals doesn't say anything about the 833 or any other xmiter tube running in class A. most of them I've seen has the AB1/AB2 or B . Having in mind the current draw from the tubes I think the filament transformer is the one that'll break someone's back when it comes the time to move it.. or.. one single transformer with all the windings in there . Phil, the 3CX300A1 is indeed interesting and.. expensive as I found out while looking at the pages on the second link you posted.they want $110.00/each.. for a tube that I can't see the insides glowing ,it's not all fun. The PP schematic I already know, saw it when I read about the tube for the first time. there is another one,but single ended that has about nothing in it only 2 tubes some other components and the transformers. The PP amp in the link uses 2 6BM8 to drive the 3CX's.. the 6BM8 alone gives a simple and reasonably good tube amp , I built two of them on a piece of wood , using transformers I had laying around here and cheapo output transformers. I have to stop being lazy and go buy some iron and copper and wind the transformer that gave me a few grey hairs while doing the maths , add the "black magic" to it and see what happens. Speaking of transformers.. the math for the 3CX300A1 gave me the following results: ( sorry but the measures are in milimeter) primary winding: 1674.1 turns of 0.1mm wire (section) secondary winding 105.86 turns of 1.58mm (closest is 1.65mm)wire (section) lamination: center "leg" of 44.4mm ,stack of the same size in height (44.4 x 44.4) gap: 0,31mm for std iron ; 0,2mm for hq iron the "black magic" : not telling it's for a 2000 ohm PP to 8ohm transformer Who'll dare to give it a try?  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 10-16-2003 06:59 PM                  $110 for a tube ain't that bad...especially for that type of tube. You outta see what the jerks on eBay are paying for tubes... I agree 100%, ya gotta see 'em glow! That's part of the "experience"... Grey hairs...at your age? Yikes! Having designed and wound tons of ac & audio xmfrs... I ALWAYS use the HQ close-gain stuff... >>> Phil  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 10-16-2003 09:54 PM                     Phil, that's why one of my away messages on some of my IM programs say, "Out of my mind...I'll be back in a few minutes." Luciano, you are correct. I found nothing about running them class A, either. I am not even sure at this point if they would be suited for audio work because most of the characteristic curves show a positive bias on the grid with respect to the cathode. Grid current in audio applications = distortion. Unless DC was used on the filaments, one would have to use some kind of hum balancing circuit also. Then again, maybe not...if the thermal inertia of the filaments is high enough.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 10-17-2003 01:15 AM                        Paul, sit and spin  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 10-17-2003 01:34 AM                     Oh, well...  |  IP: Logged Luciano Brigite Master Film Handler Posts: 277 From: Sao Paulo, SP, Brazil Registered: Jan 2002 posted 10-17-2003 01:19 PM                     Yup! grey hairs and some white ones too, I need only one year and some months to get the 30's. Guessing my age by that picture of me in the booth with the red dragon shirt will be a bit off. the picture is about 3 years old by now (btw.. I'm thinking about a new pic) While trying to get asleep in front of the computer last night I found this I think Paul G. will be interested in it the power supply for it is here Class A2 .. hrrmmm....  |  IP: Logged

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