The typo wasn't important. Besides , no-one here's ever heard of the 8751 /Y-1536 ('sept Tubelab no doubt!) so I learned something new !
Keep posting your progress. Pics if you take 'em. The EL84 is in a couple of my favourite commercial amps but I've never built anything with it myself. It would be good to learn from your build. Thanks.
Keep posting your progress. Pics if you take 'em. The EL84 is in a couple of my favourite commercial amps but I've never built anything with it myself. It would be good to learn from your build. Thanks.
I have never heard or seen that one. I don't have that number on my hard drive. A little Googling reveals a UHF planar triode that can put out a very short 2500 watt pulse at 1100 MHz. That puts it in some DME (distance measuring equipment, rangefinding) for aircraft use.
I have seen some oddball tubes in my many years of tube tinkering, but ever since I built my first PC out of dumpster finds at the IBM plant in the mid 80's, I have stored every data sheet I ever look up, vacuum tube or otherwise. Yes, this predates the WWW, but dial up BBS systems existed from the late 70's on. We accessed them with TRS-80's or Apple II clones. The Major BBS from Galacticomm was built next door to an electronics plane where I did some contract work in the 80's. Many academic institutions had BBS's full of engineering documents, some have ported all of that work to the web, but a lot of the old stuff is gone forever, especially the old documents for WWII and Korean war era military surplus electronics.
Well then, Let's fill that gap on your hard drive !
I got these years ago from Jim Cross at Vacumtubesinc. ( I just checked his website and they're not there but am pretty sure he still sells them. They came with WE archives as well.)
He hunted down the JEDEC release files along with the inter-office mail etc . The files are so big (something around 9000 items with separate index file) that it's faster to look it up on Frank's site. These days I usually don't even remember I have them until a search at Frank's turns up a blank. Nice to get some use out of them.
I got these years ago from Jim Cross at Vacumtubesinc. ( I just checked his website and they're not there but am pretty sure he still sells them. They came with WE archives as well.)
He hunted down the JEDEC release files along with the inter-office mail etc . The files are so big (something around 9000 items with separate index file) that it's faster to look it up on Frank's site. These days I usually don't even remember I have them until a search at Frank's turns up a blank. Nice to get some use out of them.
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I was trying to understand that output valve arrangement better, and noticed that the author was suggesting not to build the type D, or at least the balancing arrangement. Did you see that?
Poddwatt variants
Poddwatt variants
No, I didn't see that. I thought they all had the balancing circuit. Damn. Which version should I build then ?
So I've re-read the conversation but I don't see anything that suggests not to build this version. The D-version is the latest and apart from the mono blocks is the best version.
Ah, I missed that. Not a very big change then. The latest is a mono-block version but I don't see why I can't use this in one chassis with one PSU ?
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I'm not a member of that forum so didn't open all the images posted but at the bottom of his comparison page he writes, "As the circuit is quite versatile nearly combination of output tubes, drivers and power supplies will work well." I think he missed putting in the word every before combination.
However, the power transformer spec in the schematic you posted above doesn't look suitable to me. Its current rating is 100mA.
In the page linked it's not stated what current is running through the EL84's but his mention of bias voltage between 5V and 10V puts at the mid-point (7.5V) about 50mA per tube. So adding the 5751 puts it pretty close to max or over for just one channel. If the EL84 is run as low as 25mA it still puts it above spec for stereo. So I'd want to look at that.
However, the power transformer spec in the schematic you posted above doesn't look suitable to me. Its current rating is 100mA.
In the page linked it's not stated what current is running through the EL84's but his mention of bias voltage between 5V and 10V puts at the mid-point (7.5V) about 50mA per tube. So adding the 5751 puts it pretty close to max or over for just one channel. If the EL84 is run as low as 25mA it still puts it above spec for stereo. So I'd want to look at that.
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Can't tell what mood you're saying that in. If not feeling so enthusiastic, why not just breadboard it first?
No, it's just I had the whole amp and the PSU already built on two turret boards, looks fantastic and now I have to rethink everything including probably the chassis but hey, it keeps me off the street !