Observation: System Blue Magnetic Sensors
#1
Plated-through hole reliability:
After having poor results with both ferrite and large loops (station 1808), the Magnetic sensor pre-amp was removed and examined on a bench with a few millivolts input at 10kHz.  It was discovered that the magnetic sensor preamps were functioning as attenuators rather than as amplifiers.  Further investigation showed that the plated-through holes supplying 3.3 volts to the 4531's showed no continuity.  These were then wired-through and the preamplifiers then functioned as expected. A similar (but intermittent) issue was found on one of the RJ-45 pins.  This was remedied by applying flux to the top side of the affected pin and reheating the pin.  The flux drew solder from the lower pad through the missing plating to the top connection.  Cabling and environmental performance is currently being evaluated before returning the preamps to service.  
.... Be aware there are apparently boards that may have marginal plated-through connections.
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#2
(2019-07-12, 15:54)drossbach1 Wrote: Plated-through hole reliability:
After having poor results with both ferrite and large loops (station 1808), the Magnetic sensor pre-amp was removed and examined on a bench with a few millivolts input at 10kHz.  It was discovered that the magnetic sensor preamps were functioning as attenuators rather than as amplifiers.  Further investigation showed that the plated-through holes supplying 3.3 volts to the 4531's showed no continuity.  These were then wired-through and the preamplifiers then functioned as expected. A similar (but intermittent) issue was found on one of the RJ-45 pins.  This was remedied by applying flux to the top side of the affected pin and reheating the pin.  The flux drew solder from the lower pad through the missing plating to the top connection.  Cabling and environmental performance is currently being evaluated before returning the preamps to service.  
.... Be aware there are apparently boards that may have marginal plated-through connections.
Yes, that through issue happened on some of the earlier runs, before fabricator company was replaced... my 19.1 prerelease had a similar issue with throughs, and not just on the H amplifier...H preamp should have a gain of 6-10....   The E preamp is more of an impedance matcher, and is part of a Probe assembly, not an amplifier.. conventional terms applied to E signal would say a 'loss' of about 6db... though that is 'words only"....
.... also rememberfor H field: the onboasrd jumper pads, underneath, if you'using other than ferrites, bridge them, to change the input impedance for wire loops;.. by default they're open for ferrites.

Did you acquire your station from a previous user?  I can't match user ID, numbers, stations, info, for some reason... with the data here on the forum versus Blitzortung rosters???
And if you're the current operator, we need to get your credentials upgraded, and you need to perhaps re-register the device..

Stations: 689, 791, 1439
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#3
(2019-07-12, 15:54)drossbach1 Wrote: Plated-through hole reliability: ... Be aware there are apparently boards that may have marginal plated-through connections.

I say, I say... son, pay attention to Cutty! Big Grin

I had the same issue here. Thanks very much for sharing this.

But judging from your station number, you have a Red system, don't you?
Regards,
Mike W.
Stations: 1977, 2294
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#4
(2019-07-12, 18:47)mwaters Wrote:
(2019-07-12, 15:54)drossbach1 Wrote: Plated-through hole reliability: ... Be aware there are apparently boards that may have marginal plated-through connections.

I say, I say... son, pay attention to Cutty!  Big Grin

I had the same issue here. Thanks very much for sharing this.

But judging from your station number, you have a Red system, don't you?
I think Blues started around 1400 or so

Dries
[Image: NOAARADlogoTXT80.png][Image: forfaviconTXT.png]

Stations: 2100
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#5
(2019-07-12, 20:31)dupreezd Wrote: I think Blues started around 1400 or so

Did they? I didn't realize that.
Regards,
Mike W.
Stations: 1977, 2294
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#6
(2019-07-12, 20:37)mwaters Wrote:
(2019-07-12, 20:31)dupreezd Wrote: I think Blues started around 1400 or so

Did they? I didn't realize that.

ID 1440 here. One of the very first blues Wink
Clément
Stations: 252, 680, 733, 1440
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#7
I got the station from a prior owner and good friend who preferred that I adopt the trouble-shooting problems he was having (he did a nice job of assembly from what I could tell)....I don't know what user info is appropriate to post on the forum...Cutty, I'd be happy to provide any information you would like... do I e-mail? (my e-mail is xxxx@comcast.net).  I didn't mess with the credentials as I was hoping to convince Bill to take the station back if I got it fixed, but he prefers the present status-quo.  The station number is 1808, original user 1509.  It is definitely a Blue board set (and is so labelled although the boards are actually green in color) and it does not have the piggy-back voltage regulator board.  I jumpered the preamps when I used them with a set of 1.1 meter diameter 6 turn loops of #12 THHN (these still exist .... I built the loops when the ferrite antennas seemed insensitive).  I then removed the jumpers when I went back to the ferrites (with shielding added ...  I seem to have a strong AM station challenge locally - the board has the active filters installed and enabled),  The ferrites measure self-resonance at 1.1 MHz and read 15.3 mHy using a General Radio Bridge @ 1kHz.  The fact that "signals" didn't seem to change much between these configurations (I was monitoring with a Tek TDS 2024C 4-channel scope at the SMA ports)  is what provoked the bench testing.  The positive rail voltage was zero even though the LED indicated power.  Originally, all 3 H-Preamp channels were unpowered.  I messed with the RJ45 when the "A channel" exhibited intermittent output after fixing the power connections.  Is it possible to purchase only the pre-amp board?  I would love to populate a new one versus always wondering about the present board.  The New Mexico Sun is pretty warm.   Denny

MOD note:- emailed removed for privacy as this is on the public forum. Denny please use the PM or email option
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#8
Outstanding...  wish I had all thkt TE you have.... heh...
I assumed a transfer was the case..  Upgraded your forum status and permissions, so you now have Internal Boards access....
You seem to have a good handle on everything, and I need some coffee, but watch for a direct email from me, later today, and we'll see what else needs to be done... re station info etc..  right now, I'm trying to remember when the Power distribution changes were made in production runs..  i am slow starting at my age without a buncha caffiene ..
...heh..

Mike

Stations: 689, 791, 1439
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