WXforum.net
Weather Station Hardware => Blitzortung => Topic started by: dfroula on June 18, 2014, 10:34:58 AM
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As we have some intense lightning nearby at the moment, I've been experimenting with different combinations of H-field and E-Field gains to see if I can get usable signals from the close-in storm.
Under normal lightning activity conditions (no nearby storms and moderate nation-wide activity), I've been "tuning" the gains for roughly equal detection rates between the H-Field and E-Field amps, and so the combined rates keep me out of interference mode. This is difficult to do with nearby storms.
However, I have found that completely disabling the H-field amp (by setting 1x1 gains on both channels), and setting the E-field to moderate 5x5 gains on all three channels allows resolving the nearby strikes nicely, without going into interference.
Near-storm detection was the supposed benefit of the E-field. It certainly appears to be living up to expectations!
Don
WD9DMP
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That's good information. I've basically been dialing both E- and H-field back as storms move over me. I have to put the H-field gain at 5x1 or less, with thresholds of around 100 mV, to keep from going into interference mode so far.
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My antenna is still indoors for testing, in an electrically-quiet 2nd floor room. The antenna (30 cm, 12AWG wire, with end spiral :grin:) is on a mast up near the ceiling. That likely accounts for the reason I need to run the elevated gains for nearby strikes.
Heading out to the store for the PVC housing this morning, now that I have located suitable mounting nuts and washers for the preamp "F" connector.
Don
WD9DMP
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Check the real-time map, zoomed on Chicago. I am still detecting strikes very near to my station. I could never do this with the H-field amp!
The E-field must have great dynamic range, as I am still picking up distant strikes!
Don
WD9DMP
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Man.... you guys are lucky. Me and my E-Field are not getting along.
Joe
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Have you tried saying supportive, positive things to it? Or are you being too negative? They're dual polarity, you know -- too much of one can unbalance the system.
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Man.... you guys are lucky. Me and my E-Field are not getting along.
Joe
Sigh...
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In all seriousness, is there something we can do to help, Joe? Or is it working fine, and it's a siting issue?
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Have you tried saying supportive, positive things to it? Or are you being too negative? They're dual polarity, you know -- too much of one can unbalance the system.
Yes, I even hugged it!! :-)
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In all seriousness, is there something we can do to help, Joe? Or is it working fine, and it's a siting issue?
It has been determined that the Pre-Amp has major issues and now I have to wait for parts to be come available. Ive had some of our best checking my work... I even have sent Mike back to the coffee pot to many times!! :lol: :lol:
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In all seriousness, is there something we can do to help, Joe? Or is it working fine, and it's a siting issue?
Joe's got a bum preamp... we can't get a signal through it... This is bit of an 'off the wall' problem, that may in fact be a 'leaky' circuit board. Not a damn obvious thing, IC's been replaced.
Betcha he comes up with something simple and fools himself and me both, and we go around for a week or two muttering 'duh', duh...
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In all seriousness, is there something we can do to help, Joe? Or is it working fine, and it's a siting issue?
Joe's got a bum preamp... we can't get a signal through it... This is bit of an 'off the wall' problem, that may in fact be a 'leaky' circuit board. Not a damn obvious thing, IC's been replaced.
Betcha he comes up with something simple and fools himself and me both, and we go around for a week or two muttering 'duh', duh...
Not sure what a "leaky" circuit board is but perhaps some chewing gum might stop the leak... :twisted:
Do you have a o-scope to trace through the circuitry? There's not much on the pre-amp board to go wrong.
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In all seriousness, is there something we can do to help, Joe? Or is it working fine, and it's a siting issue?
Joe's got a bum preamp... we can't get a signal through it... This is bit of an 'off the wall' problem, that may in fact be a 'leaky' circuit board. Not a damn obvious thing, IC's been replaced.
Betcha he comes up with something simple and fools himself and me both, and we go around for a week or two muttering 'duh', duh...
Not sure what a "leaky" circuit board is but perhaps some chewing gum might stop the leak... :twisted:
Do you have a o-scope to trace through the circuitry? There's not much on the pre-amp board to go wrong.
I agree - my first thought would be a bad component (e.g. electrolytic cap, though those have gotten better over the last 5-10 years).
Remote diagnosing is always a hazardous activity :)
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In all seriousness, is there something we can do to help, Joe? Or is it working fine, and it's a siting issue?
Joe's got a bum preamp... we can't get a signal through it... This is bit of an 'off the wall' problem, that may in fact be a 'leaky' circuit board. Not a damn obvious thing, IC's been replaced.
Betcha he comes up with something simple and fools himself and me both, and we go around for a week or two muttering 'duh', duh...
Not sure what a "leaky" circuit board is but perhaps some chewing gum might stop the leak... :twisted:
Do you have a o-scope to trace through the circuitry? There's not much on the pre-amp board to go wrong.
No scope Don.... Haven't given up yet.
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Not sure what a "leaky" circuit board is but perhaps some chewing gum might stop the leak... :twisted:
You ever run into one, it'll drive you nuts... Years ago you'd see them occasionally, when devices created lots of heat. Sometimes it was obvious... usually they'd develop a 'resistive' component, which was easy to find when they'd carbonized,... Some wouldn't show up until higher voltages were impressed, and they were buggers to diagnose. Some were just manufacturing defects.
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In another life as an intern, I had to diagnose internal shorts on multi-layer boards with am inductive probe HP made for the purpose. Maddening! I developed a method using a bank of capacitors to dump a few Joules of power through the power/ground layers. It sometimes worked, sometimes created more shorts. I even blew a few holes through the board.
Hey, maybe a lightning strike would help!
Joe, I have a 'scope here. I can take a look, if you like. Likely a bad board, if Mike couldn't find the issue.
Don
WD9DMP
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Another item that can be very difficult to isolate is a combination of two factors:
- Through-hole plating bad (no electrical connection between top and bottom of board) and,
- A poorly soldered component in that same through-hole (insufficient solder to make a connection between the top and bottom of the board).
The odds of this happening are pretty slim but I have seen it happen in the past. In a few of the photos I've seen in this forum, you can see that the solder did not flow completely around the component lead on "both sides" of the board. If the through-hole plating was missing in that case and the component lead did not touch the etching on both the top and bottom, you could potentially not have a good connection and thus, a very difficult-to-find failure.
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In another life as an intern, I had to diagnose internal shorts on multi-layer boards with am inductive probe HP made for the purpose. Maddening! I developed a method using a bank of capacitors to dump a few Joules of power through the power/ground layers. It sometimes worked, sometimes created more shorts. I even blew a few holes through the board.
Hey, maybe a lightning strike would help!
Joe, I have a 'scope here. I can take a look, if you like. Likely a bad board, if Mike couldn't find the issue.
Don
WD9DMP
The thing is, I'm pretty sure all the boards have only top/bottom traces. I like your method, though.
I did run into one problem on the E-field amp board: one of the vias came filled with solder and some stray copper, and when I attempted to clean it I ended up removing the through-hole plating. That meant one of the caps didn't make a required ground connection, and I had to use the lead to connect to the ground plane at another via.
Starting to think we need a BO lab.
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Yes, but easy to fix! Just re-solder the component tops.
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Yes, all that good stuff... Joe did such a good job building his board, that we knew I'd probably destroy some stuff just removing the components for individual checks...I can tell you one thing, the impedance (resistance) to ground at the coax was about 3K instead of about 7k both polarities, after caps charged... as I measured on mine (Yeah, through 100' of coax, though)... I took several components loose, enough to check for breakdowns,... simply couldn't find any. I did question the #4 pad on the SMD, but as far as I could determine it's a floater, anyway. I was not about to pull mine off the mast and remove the IC to check it, however. Possibility remains that we received a defective replacement IC, I suppose.