EMRFD Message Archive 11530
Message Date From Subject 11530 2015-08-24 21:38:28 Adrian Scripcă Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Sorry to hijack the thread like this, but since we're on the same topic... does anybody know a source of good feed through capacitors needed for boxing the SA modules? I know Dan's small parts and kits has some at very affordable prices but unfortunately he doesn't take paypal and he only ships in the US whereas I am based in Romania.Any info would help. Thanks in advance,Adrian, YO6SSW 11531 2015-08-25 04:23:55 john lawson Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Hi Adrian.....Yep the following has high grade feedthru caps and Glass piston caps for that 110 MHz filter for the SA.Max Gain Systems. Under the doorknob search, you will find both as you scroll down near the bottom of the listing. I have used both the feedthru caps and the piston caps in my SA and they work great. Hear is the link:The feed thru cap are 5000 pf at 1KV, $.75 each or $.65 for 10 or more. They have been pulled out of military equipment, but the one's I received looked new. The glass piston caps are also mil-spec 1.1-10.2 pf. and run about 5.00 each. Hope this will help, Many thanks for the SA layouts.....I know everyone appreciates your effort......John K5IRK 11534 2015-08-25 10:05:25 Ashhar Farhan Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe there is a newer version of the VHF filter that does not use the trimmers. it is on w7zoi.net at http://w7zoi.net/bpf-ese-nhi.pdf- fOn Tue, Aug 25, 2015 at 4:53 PM, john laws 11535 2015-08-25 11:34:58 dixonglennb Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Hi Adrian,
I noticed from the pics of analyzers built by others that most boxing uses copper-clad pcb material. If that is your plan, you might try just feeding a bare wire through a hole in the wall (suitably isolated from the copper by drilling the copper out around the hole) and soldering a normal capacitor from the wire directly to the wall. With clever use of Manhattan pads, epoxy cement, and one or more surface mount capacitors good performance to UHF ought to be possible.
11536 2015-08-25 12:03:15 Ashhar Farhan Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe the really crucial pieces to be shielded are the filters. the LPF, the VHF filter, the HF filters. they can be shielded even with copper shimmings.- f 11537 2015-08-25 21:40:17 Adrian Scripcă Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Hi Glen, FarhanThank you for your advices. I have followed Vince's suggestion and ordered some feed through capacitors from Max Gain Systems so that part is covered. As for the alternative 110MHz BPF, I did read the corresponding pdf on Wes' website and your sounds like an easier replicable option. However, the kit I purchased came with three glass piston capacitors so I think I'd first want to give a try to the last version of the VHF filter described by Wes in http://w7zoi.net/mixed-bag/mixed_bag.htmlThe only thing I'm short of for the VHF filter are the teflon standoff posts for which I didn't seem to find a source yet; that and a way to tune it. I don't have a VHF signal source but certainly the 1st LO could play the role of one, given the right constant voltage for the VCO.As for the status of my build: I built all PCB modules and tested along the way so I'm left with building the LPF and VHF filters, shileding, interconnections and the likes. This is sure going to be interesting.73 de Adrian, YO6SSW 11538 2015-08-26 07:48:44 Ed Manuel Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Glenn,
I believe I recall seeing a solution to the teflon standoffs, though I did not need to use it.
My recollecton is that this was from either Bob, K3NHI or John, K5IRK.
He used small nylon screws: drill small hole to pass screw (#4 or #6 - or 1 - 2 mm), pass nylon screw into the cavity, secure with brass or nylon nut - then put two brass or nylon nuts and a small solder lug spaced above. So from the bottom, screw head, box wall, jam nut, space on the screw, nut-solder lug-nut. Use care soldering as the nylon will melt, of course - solder to the lug before you actually tighten it down. I cannot remember where I actually saw this idea. It might have been used in their Simple Tracking Generator. Bob is a genius when it comes to improvising parts like trimmers and standoffs.
I built the same filter that you are looking at. I tuned it with a Chinese SNA that sweeps from 1 to 500 mhz. Works just like designed.
11540 2015-08-26 09:29:20 n1vc Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Surplus sales of Nebraska....Vince
Feedthru Caps - Hole Mount Index
11541 2015-08-26 09:40:55 john lawson Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe Hi Glenn and Ed, Yes I did build one using the nylon screws for standoffs and it worked FB....however another experiment I used was to use #12 wire without any standoffs at all....the wire was stiff enough to stay in place and have used it for several years that way with no problems from any vibration and other things that would be of concern......In total I've built the revised filter three times and swept all three which showed the desired trace results...The third one did have the standoffs that Wes mentioned in his paper...Hope this helps in giving you some ideas on how to solve the problem.....best of luck John K5IRK 11549 2015-08-26 22:18:41 email@example.com... Re: Feed through capacitors source (Was: Looking for W7ZOI/K7TAU Spe HERE IS A SELLER OFFERING 1000pF ones 50 NOS AT $6/-
http://danscloseoutsandspecialdeals.com/specialdealsandleftovers.html SEE down the link, It is a new item offered