All of the large ROUND holes can be used for ventilation or mounting. They are all electrically isolated. Ideally one or two could be used for additional mounting holes, but I wouldn't block a bunch of them.
The two OCTAGONAL holes near one of the output tubes are for ventilation of the resistor that I tried to fry this morning. They are electrically grounded. Using these for mounting could create a ground loop. The resistor and zener reduces the heat load in the mosfets by dropping the drain voltage to 150 volts.
The mosfet area was the hot spot in the old TSE, so I spread it out, put some holes in the board, and reduced the voltage a bit.
The two OCTAGONAL holes near one of the output tubes are for ventilation of the resistor that I tried to fry this morning. They are electrically grounded. Using these for mounting could create a ground loop. The resistor and zener reduces the heat load in the mosfets by dropping the drain voltage to 150 volts.
The mosfet area was the hot spot in the old TSE, so I spread it out, put some holes in the board, and reduced the voltage a bit.
Last edited:
Fantastic! I really appreciate you souping up the 2.5 volt capabilites. I always liked the sound of 2a3's in the TSE. If I remember right, those Chinese ones were some of the worst offenders for overheating the filament regulator. I never considered running those at 385 volt. I wonder how long they would last like that.
Geez... Hope you're feeling better soon, George. That sounds like an ordeal. I just learned a coworker received a similar "nasal appraisal" from his doc, but at least he didn't wind up in the ER. Here we're blaming it all on the crappy weather we've had here for the past several weeks.
I wouldn't mind a bit paying $20 extra to source the parts. My preference would be for the gold-plated sockets - but again, I wouldn't complain either way.
Touche. I recently purchased a pair of boards from another forum member (*ahem*). They weren't "cheap", but they were a good value, and for the same reasons listed above. Plus he provided courteous answers to my questions, documented his product thoroughly, and shipped them promptly. A stand-up product from a stand-up guy - what's there to whine about?
I wouldn't mind a bit paying $20 extra to source the parts. My preference would be for the gold-plated sockets - but again, I wouldn't complain either way.
Last edited:
I wasn't aware that New Sensor ever sold Chinese tubes since their factories are in St. Petersburg Russia.
Mine are from the late 90's and I got them from ESRC.
They have never been north of 325 volts until yesterday. I had a new in the box Hammond 372HX that I got for an experiment in parallel wired SPP boards. When it was time to test the TSE-II it was the only power transformer that I had with enough heater current capability to feed 2A3's. I used a Variac to test at low line voltage when verifying regulator function. Low line is worse case for hum issues. Yesterday I decided to explore the other end of the Variac dial. The 2A3's didn't seem bothered at all.
I do have a pair of Sovtek 2A3's here somewhere, as well as some old RCA's, which I won't abuse.
I was a bit surprised to read that voltage, and thought it might be a typo - but not too surprised considering the source. I was lucky enough to lay in a good supply of 45s and 2A3s back when used examples were relatively cheap. The beefed-up filament supply on the new board is what's prompted me to pull the trigger once it's available.
I'd like to try both tube types if possible (the final amp will use a pair of James OPTs with multiple taps). As much as I hate to "waste" old tubes, I do have one weak 45 that's reserved for a 1920's-style transmitter so I can legitimately participate in the AWA's 1929 night.
I'd like to try both tube types if possible (the final amp will use a pair of James OPTs with multiple taps). As much as I hate to "waste" old tubes, I do have one weak 45 that's reserved for a 1920's-style transmitter so I can legitimately participate in the AWA's 1929 night.
I put the new pushrod in the mower this morning and promptly bent it by turning the motor over by hand. The exhaust valve was stuck closed. Upon regaining some of my patience I realized that the valve guide had been pushed mostly out of the head and was holding the valve closed. I pounded the guide back into the head, straightened out the pushrod the best I could, and reassembled. The motor fired right up and ran good. How long will it last? The right fix is a new head....
We have been in a 6 year battle with Japanese Knotweed....I buy concentrated Glyphosate by the 2.5 gallon jug.
The right fix might be a new head, but at about $250 for a bare head......the real fix will be to buy a used head with valves, springs and rockers on Ebay for $45. I also ordered a gasket set and another pushrod. Total expense for the repair maybe $70. The mower is 15 years old and it came with the property we bought......non running of course. Sherri wants a new John Deere......It will be far cheaper in November than now, so this needs to run until then, then it becomes the "do the dirty jobs" machine, but here all of them are dirty jobs.
It could have been them, but I got the good Coke Bottle 6L6GC's from AES. The junky ones were $3 and $4 each on Ebay.
Had to read that a second time for me to realize you weren't talking about beer ("bottle Round-Up" vs. "bottle of Round-Up"). Lysdexia strikes again......or a bottle of Round-Up. Brown is the new green, ya know...
Talk about terrible timing; not only is it the beginning of the mowing season, but I just parted out my in-laws' mower with an identical engine not six months ago - in WV. The mower itself was rusty, but the engine was sound. I'd have let you have it for nothing.
I just got through retiring a consumer grade JD with a 22 or 24 horse V twin. The frame, engine, tuff torq trans, all held up well, but the decks are weak and problematic - at least in my experience. I was using it pretty hard, dragging it across two states on a trailer, mowing several acres at each location, plus my yard.
Last year, I replaced it with a zero turn Ariens, which may or may not hold up to my use. So far, when it doesn't leak, it's been okay. All the rain here has already put me behind on my mowing.
Personally, I don't think a zero turn is any advantage over the tractor type when you are just sitting and mowing empty acreage.
I see they're now after Round Up as a carcinogen. I used it as a kid. I had non Hodgkin's lymphoma in my early 30's. Probably just a coincidence.
Win W5JAG
Last year, I replaced it with a zero turn Ariens, which may or may not hold up to my use. So far, when it doesn't leak, it's been okay. All the rain here has already put me behind on my mowing.
Personally, I don't think a zero turn is any advantage over the tractor type when you are just sitting and mowing empty acreage.
I see they're now after Round Up as a carcinogen. I used it as a kid. I had non Hodgkin's lymphoma in my early 30's. Probably just a coincidence.
Win W5JAG
I have been using the Edcor power transformer that someone designed specifically for this amp, but with a 10 amp, 6 volt Hammond for the filaments. I have melted a trace or two off the board when things have gone south. I have a set of Shuguang 2a3 (the first series with the 98 on the glass) that look very much like the ones in that picture. I bought an old Webster amp from a church PA system years ago that has 4 vintage 2a3s in it. I think 2 Sylvanias were the originals and 2 Tung Sols were replaced at some point. It cost me $100 and came with 4 70+ year-old Jenson field-coil speakers that I don't know what to do with, but hate to throw away. The Tung Sols sound remarkable in the TSE. (The Sylvanias probably do too, but I don't have a tube tester for 4 -pin, and one looks a little jankey)
There is much more to it than that. Monsanto created Roundup. They also created genetically modified versions of several popular grains like corn and wheat that are resistant to Roundup. Google "Roundup Ready Corn." The label states that the farmer should not apply Roundup to his food crops within so many days of harvest, but does everybody use the products according to label?
Cheerios and some other popular breakfast cereals have tested positive for Glyphosate.
I don't know about the current vintage JD's but my lawnmower is a "Southern States" brand from the local farmers Co-op. I went to the Co-op looking for parts to find that they no longer sell mowers or tractors, but the guy there told me just to stick my model number into Google and I would find everything I need. It seems that all of the major brands are made in an American Yard Products factory and almost all the parts interchange.
The deck got so bad that two blades hit each other and parts came flying out. So now its rebuilt with some JB weld and aluminum window screen, Husquavarna, Poulan, Craftsman, and JD parts. The belts are Craftsman from Amazon, and the engine parts are genuine Briggs and Stratton also from Amazon.
I have some Shuguang 300B's with the 98, but these 2A3's don't have the 98. They are all from the same era, around 2000. I have no idea what that means, but all of the tubes still work fine. Many of my Sovtek's from that era have died. The filament, or half of it has gone open with no visible break. The crimp seema to have failed. New Sensor refused to make good on some tubes that died a few months after purchase.
Good time to buy the regular style garden tractors now, as seemingly every man wants a zero turn.I have an old Scotts/Murray(no not John Deere made) 1998 with Kohler Command 15hp that still works fine for some reason.The Kohler Command may be an engine to look at as a repower.I hear not to own the Kohler Courage engines.Looking back, we used Hustler zero turns in the early 80,s at a golf course I worked at.Point is, zero turns really aren't a new design.
I had some trouble with cheap 4 pin sockets....bad contacts. I ordered some of these from China, took about a month to get here, but they are a nice quality. Also the cheapest I could find.....2 x 4pin 300B 5Z3 UX4 2A3 274 572 B 811 812 A Gold Ceramic Vacuum Tube Socket | eBay