Timeline for Why is my diplexer such a spectacular failure?
Current License: CC BY-SA 4.0
22 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 11, 2020 at 11:15 | comment | added | Dieter Vansteenwegen | google.com/url?q=http://www.w1npp.org/events/2010/2010-f~1/ATV/… | |
| Jul 11, 2020 at 0:43 | comment | added | user14945 | @Dieter Sure, I would like to see that. | |
| Jul 9, 2020 at 6:38 | comment | added | Dieter Vansteenwegen | There was an article in QEX I think that used coax stubs instead of passives. Seemed to work well and easier to build. Can look it up for you if you'd like... | |
| Jul 9, 2020 at 1:57 | comment | added | user14945 | @Dieter I did just recently discover this site hb9abx.no-ip.biz/diplexer.htm and I did find it notable that the author specifies three particular coils that need to be physically oriented at separate right angles to each other to minimize coupling. I didn't try that yet, so who knows. What I did do is purchase a cheap manufactured diplexer from a "reputable" company, and it also produces an unacceptable SWR curve...so now I'm not even sure what I should be expecting from a given experimental design. | |
| Jul 9, 2020 at 1:49 | comment | added | user14945 | @Dieter Vansteenwegen ON4DD Sadly...no. After trying various ways of coupling the PCB to the coax connectors with no real improvement in SWR, I removed the PCB and rebuilt the circuit using leaded caps and handmade inductor coils - SWR was still unacceptably high, but not as high as the PCB version. I did have to parallel some caps to obtain closer value approximations, and it was difficult to maintain the geometry of the coils..ugh...haven't yet decided exactly how to proceed. | |
| Jul 8, 2020 at 8:37 | comment | added | Dieter Vansteenwegen | @TylerStone Did you get this sorted out? How? | |
| May 9, 2020 at 12:38 | answer | added | Ngineer | timeline score: 2 | |
| May 7, 2020 at 6:39 | comment | added | user14945 | @Brian K1LI to your previous question; without the diplexer in the mix, there can be only one antenna connected to the feedline at a time. | |
| May 7, 2020 at 3:58 | comment | added | user14945 | @Brian K1LI I understand..it's going to be a minute before I get to the bottom of this, and it's not helpful that I uploaded an incorrect schematic image. | |
| May 7, 2020 at 3:56 | history | edited | user14945 | CC BY-SA 4.0 |
attempting to replace incorrect image with correct image
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| May 7, 2020 at 3:44 | history | edited | user14945 | CC BY-SA 4.0 |
attempting to replace incorrect image with correct image
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| May 6, 2020 at 11:20 | comment | added | Brian K1LI | @TylerStone If it becomes appropriate, please remember to mark a suggestion as "answered" so yours comes off the list of "unanswered" questions. | |
| May 5, 2020 at 21:00 | history | tweeted | twitter.com/StackHam/status/1257777090411159552 | ||
| May 5, 2020 at 14:17 | history | became hot network question | |||
| May 5, 2020 at 13:58 | comment | added | tomnexus | Your coax connections aren't really ok for VHF or UHF, they might be contributing to the high SWR. PCB construction looks great! How does it perform when both antenna ports are terminated in 50 Ohms? Try some 47 Ohm chip resistors on the outputs instead of cables? | |
| May 5, 2020 at 10:48 | answer | added | Brian K1LI | timeline score: 5 | |
| May 5, 2020 at 10:41 | answer | added | vu2nan | timeline score: 5 | |
| May 5, 2020 at 10:16 | comment | added | Brian K1LI | @TylerStone Without the diplexer, what do you measure on each band if you disconnect the antenna for the other band? | |
| May 5, 2020 at 6:47 | comment | added | Buck8pe | Just checked my Elsie version and it certainly does insist on source and load impedances. It doesn't seem that easy to alter the design it gives you like it does other filter types, but it does offer to create an LTSpice schematic. Once you get it into LTSpice, you could play around with the values, I suppose. | |
| May 5, 2020 at 6:37 | comment | added | user14945 | @Buck8pe Hey, thanks...I'll have a look at that. | |
| May 5, 2020 at 6:32 | comment | added | Buck8pe | I'm no expert, so I'll put this as a comment, but those LC filters are dependent on source and load terminations. I suggest you use Elsie (tonnesoftware.com/elsie.html) to reverse engineer your design - it's free and it even has a diplexer option! Just plug in your existing values (with terminations where appropriate) and see what you get. | |
| May 5, 2020 at 6:07 | history | asked | user14945 | CC BY-SA 4.0 |