Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
K7ITM wrote:
...(I've built several somewhat similar filters using copper clad for the shielding, and they work quite well.) Would a suggested design be helpful?.. I would like to hear of your designs, please. Particularly how you physically work the copper fabrication/solder etc. Thanks - Craig 'Lumpy' Lemke www.n0eq.com |
#2
![]() |
|||
|
|||
![]()
On May 8, 3:03 pm, "Lumpy" wrote:
K7ITM wrote: ...(I've built several somewhat similar filters using copper clad for the shielding, and they work quite well.) Would a suggested design be helpful?.. I would like to hear of your designs, please. Particularly how you physically work the copper fabrication/solder etc. Thanks - Craig 'Lumpy' Lemke www.n0eq.com Hi Lumpy, I'm fortunate to have access to a shear that cuts fiberglass/epoxy board stock reasonably cleanly. I use all double-sided stock, copper- clad on both sides. I typically set up the stop for, say, 2 inches, and make a bunch of square pieces. They'll become end pieces and partitions between "cells". Then I cut a couple 2 inch wide strips using the same setup; these will be the sides, and they are whatever length I need. The base piece is typically a quarter inch wider (or a bit more) and the same length as the sides. I plan out where I need holes, and punch them in the partitions and end pieces (or sides, if that's what I want). Then I tack one of the square pieces just short of the end of the base, so I can solder it to the base on both sides. Same on the other end. Then side pieces go in, tack-soldered to the base and the two end pieces. Avoid tacking where partitions will go. Put in partitions where you want, and tack them. Then run a bead of solder along each place where two pieces of copper-clad come together. Occasionally I'll also put in something to support coils or wires, too. Then I built the filter...soldering some parts to the copper clad for ground. Some filters I can get by with a minimum of partitions. I would expect for a sharp cutoff filter like the "FD adjacent band" filter that I'd need to use a partition to separate any two adjacent resonators. When I first started making filters this way, I was expecting to have to seal off the open end of each cavity. The description above only puts copper-clad on five of the six sides of each cell. I was amazed to find that it's practically never necessary to do that. For example, I have a 1MHz bandpass filter that has stops specifically at 2MHz and 3MHz. I used it to clean up the output of a signal generator so I can test for harmonic distortion. That filter shows about 120dB attenuation at 2 and 3 MHz, in spite of the open-topped cells. If a picture would help, I'd be happy to send one via email. Cheers, Tom |
#3
![]() |
|||
|
|||
![]()
K7ITM wrote:
I'm fortunate to have access to a shear that cuts fiberglass/epoxy board stock reasonably cleanly. . . For those of us who don't, I've found that tin snips do a good job and without the irritating dust you get if you saw it. Roy Lewallen, W7EL |
#4
![]() |
|||
|
|||
![]()
Roy Lewallen wrote:
K7ITM wrote: I'm fortunate to have access to a shear that cuts fiberglass/epoxy board stock reasonably cleanly. . . For those of us who don't, I've found that tin snips do a good job and without the irritating dust you get if you saw it. Roy Lewallen, W7EL I've also used a table saw with a VERY fine-pitch blade, set just above the table. It makes nice 90° corners. A Shop-Vac keeps the dust from getting out of hand. 73, Bryan WA7PRC |
#5
![]() |
|||
|
|||
![]()
K7ITM wrote:
...(I've built several somewhat similar filters using copper clad for the shielding, and they work quite well.) Would a suggested design be helpful?.. If a picture would help, I'd be happy to send one via email. I'd like to see pics please. My return is valid. Thanks mucho Craig 'Lumpy' Lemke www.n0eq.com |
#6
![]() |
|||
|
|||
![]()
On May 8, 9:56 pm, "Lumpy" wrote:
K7ITM wrote: ...(I've built several somewhat similar filters using copper clad for the shielding, and they work quite well.) Would a suggested design be helpful?.. If a picture would help, I'd be happy to send one via email. I'd like to see pics please. My return is valid. Thanks mucho Craig 'Lumpy' Lemke www.n0eq.com I've posted some pix at http://mysite.verizon.net/bruhnstv/. They'll be there for a short time. Cheers, Tom |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Working home station and club station field day 2005 | Policy | |||
WTB Isolation Transformer | Swap | |||
Broadcast Station Field Strengths.. | Antenna | |||
isolation transformer | Equipment | |||
isolation transformer | Equipment |