Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
Ero-Shan:
--- Quote from: BravoV on May 04, 2018, 04:31:38 am ---
Well, at the Trueposition GPDSO big thread here, there are success using small patch antenna.
I'm a noob too, lets alone RF things, from what I read at the datasheet, the Furuno GPS receiver can drive a 50 Ohm LNA/active antenna at 5V 20ma, as this is typical for GPS.
Some can get good signal using small antenna at window sill like bd139 does, while here, I don't that kind of luxury as at window even I protruded the antenna head out, its still blocked by the longer protruding roof and also lots of trees with dense leafs, and the best only at 2 or 3 satellites and unstable. :-[
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I'll probably order one of those less than 10 € ones just for a test (until the thing arrives it should be warm enough to open a window). I'm going to have major problems finding a hole to the outside to stick the cable through.
--- Quote ---Keep me updated too as I want to learn from your experience.
--- End quote ---
I read: Keep me updated too as I want to learn from your errors. ;)
bd139:
--- Quote from: Specmaster on May 03, 2018, 11:09:10 pm ---
--- Quote from: GerryBags on May 03, 2018, 10:42:44 pm ---I have a couple of new 75 Ohm panel mount BNC's from Amphenol if you need one, Specmaster? They came in a joblot.
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thanks, I'll get back to you on this, I'll guided by bd139 on if I actually need to do this as he's more in to this more than I am as ham operator.
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You don’t need this for aligning radios as you’re probably good enough just loosely coupling the generator to the antenna but it’s a convenience. The panel mount BNCs are on the mark though.
When i calibrate a receiver I’ve built i use a BNC patch with a 50 ohm through terminator plugged into the receiver’s antenna port. Either that or it’s perfectly acceptable to literally just stuff a bit of wire around the antenna and plug that into the generator. As long as you have gobs of the fundamental then you’re good.
There’s a surprising lack of science when it comes to RF sometimes :)
Edit: typical RX calibration for SSB/CW on 7Mhz.
1. Stuff a bit of wire in the antenna hole and into the generator
2. Set for 7.1MHz mid band, tune it and adjust front end filter for loudest signal.
3. Set for 7.2MHz top end of band, set VFO control to highest frequency, tune VFO centre for signal
4. Set for 7.0MHz bottom end of band, set VFO control to lowest frequency, tune VFO span for signal
5. Repeat 3/4 until it’s about right.
6. Loosely couple marker generator to antenna.
7. Set on 1MHz and tune VFO centre on low tuning again for 7.0MHz.
8. Set on 100KHz and draw the 100KHz marks on the dial
9. Set on 10KHz and draw the 10KHz marks on the dial
Sorted :-+
BravoV:
--- Quote from: Ero-Shan on May 04, 2018, 05:39:25 am ---I'll probably order one of those less than 10 € ones just for a test (until the thing arrives it should be warm enough to open a window). I'm going to have major problems finding a hole to the outside to stick the cable through.
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Yeah, that is wise, I did the same testing using my friend's car GPS antenna, its just failed miserably and also its not designed to be truly outdoor antenna as mine will be placed high at/above roof level.
For sure I need to have it placed that high,and this change the simple antenna task into another beast compared to small & cheap at window's antenna, this is one of my potential -> Problem :(
Hope your cheap solution works as planned.
--- Quote from: Ero-Shan on May 04, 2018, 05:39:25 am ---I read: Keep me updated too as I want to learn from your errors. ;)
--- End quote ---
LOL ... :-DD
bd139:
Talking of GPS I think I (or my youngest) killed my QRP Labs GPS module. It's not responding now. Was sitting there on the window sill. There was a two hour opportunity where my youngest may have got at it but I couldn't see any finger prints on the board!
Haven't replied to any of the GPS antenna posts yet but have been reading them. I'm looking at permanent antenna options as well so this thread is interesting :-+
BravoV:
--- Quote from: bd139 on May 04, 2018, 06:26:21 am ---Talking of GPS I think I (or my youngest) killed my QRP Labs GPS module. It's not responding now. Was sitting there on the window sill. There was a two hour opportunity where my youngest may have got at it but I couldn't see any finger prints on the board!
--- End quote ---
Wow :o .. you put that bare board, powered & unprotected near the window for all this time ?
C'mon, get a cookies box or something and put that thing in there ...
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