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Biz WDØHCO wrote:
After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Opinions ? Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. Thanks Biz - WDØHCO Do you have a good drill press? You can buy either a 4" hole saw, or an adjustable cutter that drills a pilot hole, then uses a lathe tool to cut a clean hole in the metal. They cut a fairly clean hole, but the metal has to be clamped down, and the tool has to run at a low speed. -- Michael A. Terrell Central Florida |
Filament Question
Biz WDØHCO wrote:
After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Opinions ? Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. Thanks Biz - WDØHCO Do you have a good drill press? You can buy either a 4" hole saw, or an adjustable cutter that drills a pilot hole, then uses a lathe tool to cut a clean hole in the metal. They cut a fairly clean hole, but the metal has to be clamped down, and the tool has to run at a low speed. -- Michael A. Terrell Central Florida |
in article , Michael A. Terrell at
wrote on 10/28/03 7:38 PM: Biz WDØHCO wrote: After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Opinions ? Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. Thanks Biz - WDØHCO Do you have a good drill press? You can buy either a 4" hole saw, or an adjustable cutter that drills a pilot hole, then uses a lathe tool to cut a clean hole in the metal. They cut a fairly clean hole, but the metal has to be clamped down, and the tool has to run at a low speed. Why yes I do and I can change speeds on it. But I thought those hole saws where for wood only. BTW Aluminum panel is pretty soft so this might actually work. Do they make hole saws for metal? Saw a gizmo called a "fly cutter" used on a drill press to cut holes. It looked pretty dangerous. I think that's what you are talking about. Looks like a trip to Sears is in order! :^) Biz WDØHCO |
Behold, Biz WD=?ISO-8859-1?B?2A==?=HCO signalled from keyed 4-1000A
filament: After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Awesome!! I have a beautiful all-tube SW RX (my dream too) on the go :-) Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Yes. As an audio/RF builder, I power all my filaments from DC. For up to 1 amp, a 7805 with two 1N400x in series with the groud pin will do fine. For more current, an LM4558 driving a 2N3053/3055 in a darlington arrangement is great for up to about 6-8 amps. Goos success to you! -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Behold, Biz WD=?ISO-8859-1?B?2A==?=HCO signalled from keyed 4-1000A
filament: After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Awesome!! I have a beautiful all-tube SW RX (my dream too) on the go :-) Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Yes. As an audio/RF builder, I power all my filaments from DC. For up to 1 amp, a 7805 with two 1N400x in series with the groud pin will do fine. For more current, an LM4558 driving a 2N3053/3055 in a darlington arrangement is great for up to about 6-8 amps. Goos success to you! -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
On Tue, 28 Oct 2003 20:55:41 -0600, Biz WDØHCO wrote:
in article , Michael A. Terrell at wrote on 10/28/03 7:38 PM: Biz WDØHCO wrote: After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Opinions ? Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. Thanks Biz - WDØHCO Do you have a good drill press? You can buy either a 4" hole saw, or an adjustable cutter that drills a pilot hole, then uses a lathe tool to cut a clean hole in the metal. They cut a fairly clean hole, but the metal has to be clamped down, and the tool has to run at a low speed. Why yes I do and I can change speeds on it. But I thought those hole saws where for wood only. BTW Aluminum panel is pretty soft so this might actually work. Do they make hole saws for metal? As Michael has said they do make hole saws for metal as well. It does take a "rugged" drill press though to keep the saw cutting a nice clean hole. Saw a gizmo called a "fly cutter" used on a drill press to cut holes. It looked pretty dangerous. The "Fly Cutter" is a great tool for cutting clean holes. I'd much rather use it on a milling machine though. And...yes, it does take some precautions and it needs to run pretty slow. Course when cutting metal the number of teeth per inch depends on what you are cutting as does the speed. Most drill presses run a bit fast even at their slowest speed for cutting metal, but mine seems to do OK, although it grabs like crazy when breaking through And use the proper cutting oil to help keep the teeth from clogging and the saw from binding. Use some good, flat clamps so the piece is held rigidly. It shouldn't flex, no move in any axis. I've had the pleasure...and embarrassment of having a big drill bit take a pretty hefty chunk of aluminum away from me and then start slapping the column with it. This was in a machine shop. I hit the power switch and dove...There wasn't one person standing up until it got quiet...very quiet...then all you could see were eyes peaking up over the benches. Each one afraid of what they might see. Roger Halstead (K8RI EN73 & ARRL Life Member) www.rogerhalstead.com N833R World's oldest Debonair? (S# CD-2) I think that's what you are talking about. Looks like a trip to Sears is in order! :^) Biz WDØHCO |
On Tue, 28 Oct 2003 20:55:41 -0600, Biz WDØHCO wrote:
in article , Michael A. Terrell at wrote on 10/28/03 7:38 PM: Biz WDØHCO wrote: After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Opinions ? Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. Thanks Biz - WDØHCO Do you have a good drill press? You can buy either a 4" hole saw, or an adjustable cutter that drills a pilot hole, then uses a lathe tool to cut a clean hole in the metal. They cut a fairly clean hole, but the metal has to be clamped down, and the tool has to run at a low speed. Why yes I do and I can change speeds on it. But I thought those hole saws where for wood only. BTW Aluminum panel is pretty soft so this might actually work. Do they make hole saws for metal? As Michael has said they do make hole saws for metal as well. It does take a "rugged" drill press though to keep the saw cutting a nice clean hole. Saw a gizmo called a "fly cutter" used on a drill press to cut holes. It looked pretty dangerous. The "Fly Cutter" is a great tool for cutting clean holes. I'd much rather use it on a milling machine though. And...yes, it does take some precautions and it needs to run pretty slow. Course when cutting metal the number of teeth per inch depends on what you are cutting as does the speed. Most drill presses run a bit fast even at their slowest speed for cutting metal, but mine seems to do OK, although it grabs like crazy when breaking through And use the proper cutting oil to help keep the teeth from clogging and the saw from binding. Use some good, flat clamps so the piece is held rigidly. It shouldn't flex, no move in any axis. I've had the pleasure...and embarrassment of having a big drill bit take a pretty hefty chunk of aluminum away from me and then start slapping the column with it. This was in a machine shop. I hit the power switch and dove...There wasn't one person standing up until it got quiet...very quiet...then all you could see were eyes peaking up over the benches. Each one afraid of what they might see. Roger Halstead (K8RI EN73 & ARRL Life Member) www.rogerhalstead.com N833R World's oldest Debonair? (S# CD-2) I think that's what you are talking about. Looks like a trip to Sears is in order! :^) Biz WDØHCO |
Biz WD=?ISO-8859-1?B?2A==?=HCO wrote:
After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Depends on the tubes you're using. Some tube designs have real problem with noise coupling from the filament, some do not. Sometimes it varies, too. The Russian 6SN7 and 6SL7 tubes have serious coupling issues, the old Raytheons do not. But the old GEs do. If you run DC, you don't have to worry about it. Running DC filaments also means you can ramp the filament supply up more slowly too, by using big filter caps for a long time constant. This tends to make tubes last longer. Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. You CAN drill large holes in aluminum with a hole saw intended for wood. Not one of the adjustable ones, but one of the formed metal ones like Black and Decker sells, where you have one center assembly that holds a centering bit and then a formed metal blade for each size that screws into the center assembly. Run very, very slow and keep the blade as wet as possible with cutting oil or automatic transmission fluid. If you are careful you can get a nice cut this way. It will wear the blade a lot more quickly than wood, of course. However, if you do this a lot, a Greenlee punch is the way to go. You don't need a hydraulic one either, just one of the screw-in ones that you crank down by hand. Even so, a 4" punch will run you over a hundred bucks, as opposed to fifteen or twenty bucks for a cheap hole saw kit. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Biz WD=?ISO-8859-1?B?2A==?=HCO wrote:
After 31 years and a bunch of parts in the garage, I am finally building my dream CW receiver from scratch. Just wondering if I converted the 6.3 VAC filament voltage to a DC voltage if doing so would be worth the effort to reduce hum. Depends on the tubes you're using. Some tube designs have real problem with noise coupling from the filament, some do not. Sometimes it varies, too. The Russian 6SN7 and 6SL7 tubes have serious coupling issues, the old Raytheons do not. But the old GEs do. If you run DC, you don't have to worry about it. Running DC filaments also means you can ramp the filament supply up more slowly too, by using big filter caps for a long time constant. This tends to make tubes last longer. Also I would like to cut a round 4" diameter hole in the 1/8" aluminum front panel for the speaker grill. Is there a way to do this without a Greenlee Pneumatic punch? I have a jig saw which I can cut square holes but round holes are another matter. Is there a better way? I can drill round holes up to 7/8" with a unibit but I think 7/8" is as big as they get. You CAN drill large holes in aluminum with a hole saw intended for wood. Not one of the adjustable ones, but one of the formed metal ones like Black and Decker sells, where you have one center assembly that holds a centering bit and then a formed metal blade for each size that screws into the center assembly. Run very, very slow and keep the blade as wet as possible with cutting oil or automatic transmission fluid. If you are careful you can get a nice cut this way. It will wear the blade a lot more quickly than wood, of course. However, if you do this a lot, a Greenlee punch is the way to go. You don't need a hydraulic one either, just one of the screw-in ones that you crank down by hand. Even so, a 4" punch will run you over a hundred bucks, as opposed to fifteen or twenty bucks for a cheap hole saw kit. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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