- help solving an HF radio amps issues - 1 Update
- 6 V variable power supply for illumination in Zeiss microscope. - 4 Updates
- Mechanical damping of panel meters - 2 Updates
| Gary Shaddick <none@nowhere.net>: Sep 11 11:19AM -0400 A fellow ham operator is having a problem: every time he transmits with an amplifier in place, he either blows the amplifier fuses and/or destroys the tubes if using the tube unit he has. He has been keeping drive to the amp as recommended and even has tried low drive first, but once he tries full output on either amp, they go out. He's tried different antennas but to no avail. He can run the radio by itself at 200 W into any of his antennas with no issues whatsoever (the amp is 500 W). His SWR's have been normal, even at the time the amps stop working. Notice I said amps because the same behavior happens on both of the two amps he owns. I've suggested possible RFI issues somehow causing the issue, but this is just a guess. I'm just as perplexed as he is. Any thoughts you have would be welcome and I could run suggestions by him. Thanks in advance, Gary |
| peter@easthope.ca: Sep 10 10:55AM -0700 Hi, The supply in this photo powers an incandescent bulb of a Zeiss microscpe. http://easthope.ca/ZeissLampSupplyLPS7.5.jpg That supply accepts 110 V input. The bulb is marked 6 V 15 W. For several decades, the 'scope was commoplace in North America. Likely a similar supply accepting 220 V input was common outside North America. I want to find a power adapter which accepts 220 V input. eBay has this and similar listings. https://www.ebay.ca/itm/185935059631 If the output connection is compatible with the plug on the lamp cord, the supply should work but the total price is approximately 670 Canadian dollars. =8~/ Rather pricey to power a small bulb. A simple alternative is a 6 V brick adapter and potentiometer. Other ideas? Thanks, ... Peter E. |
| John Robertson <jrr@flippers.com>: Sep 10 10:49PM -0700 > A simple alternative is a 6 V brick adapter and potentiometer. > Other ideas? > Thanks, ... Peter E. Simple to make a PWM (Pulse Width Modulation) power supply for 6VDC at a few amps. Cost well under $100 with enclosure. You need a pot that handles at least 15W, preferably 25 to 50W to avoid overheating. Something like this, but it would draw 1/2A if wired across the 6VDC supply: https://flippers.com/catalog_oc/bat-power-potentiometer-5a-6202 Or if you can find a 24 to 50 ohm 50W potentiometer/rheostat. John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| Jeff Layman <Jeff@invalid.invalid>: Sep 11 07:56AM +0100 > Canadian dollars. =8~/ Rather pricey to power a small bulb. > A simple alternative is a 6 V brick adapter and potentiometer. > Other ideas? I assume you don't have the 110V power supply (or you do have it and it doesn't work) as then the simplest solution would be a 220V - 110V transformer. If you don't have the supply, can you get a connector for the microscope power supply, or would you have to modify the wiring? Anything here cheaper and suitable: <https://picclick.com/Popular/zeiss-power-supply> -- Jeff |
| "John Keiser" <johnkeiser@juno.com>: Sep 11 02:47PM > A simple alternative is a 6 V brick adapter and potentiometer. > Other ideas? > Thanks, ... Peter E. Temu [usually ships quickly fron US] or AliExpress [ships slow from China] has low volatage PWM motor controls for only a few dollars that you could adapt. |
| Andrew Smallshaw <andrews@sdf.org>: Sep 11 11:27AM Hi all I've recently picked up an old Weir bench PSU and recalibrated it to within quite sharp tolerances. However, the front panel meter (switchable between voltage and current, although the schematic shows it is working as voltmeter in both modes) reads accurately, but the settling time must be a good 10-15 seconds before it stops oscillating back and forth. I haven't got as far as pulling the meter out yet but I expect obtaining a compatible replacement will be difficult. Looking at online it seems most practical sources sources address electrical damping for brief transients in the signal, this is rather the mechanical side of things. Basic research suggests pneumatic damping is the usual order of the day but I haven't found anything relating to actual maintenance and adjustment. Does anyone have practical experience or is a replacement meter the usual approach? -- Andrew Smallshaw andrews@sdf.org |
| legg <legg@nospam.magma.ca>: Sep 11 09:13AM -0400 On Mon, 11 Sep 2023 11:27:28 -0000 (UTC), Andrew Smallshaw >relating to actual maintenance and adjustment. >Does anyone have practical experience or is a replacement meter >the usual approach? . . . . unless the meter is reading a real disturbance . . . There's probably a failed capacitor inside that needs replacing. Could even be an electrolytic across the meter terminals. Most sensitive moving coil meters (<1mA) are pretty much self- damping and won't require much filtering to average a measurement. RL |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 7 updates in 3 topics"
Post a Comment