Author Topic: Inside the Boltek antenna  (Read 4472 times)

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Offline JupiterJoe

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Inside the Boltek antenna
« on: September 29, 2016, 07:28:35 PM »
Well, I recently had one fail on me, so I decided to see what was in the old one. This was easier said than done because the housing is not hollow with an antenna board bolted in. It's a complete chunk of plastic melted over the electronics into a box shape!
Pretty interesting, it's just two directional ferrite antennas with thick copper wiring around them, a circuit board and an ethernet connector.











« Last Edit: September 30, 2016, 11:00:26 AM by JupiterJoe »

Offline DanS

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Re: Inside the Boltek antenna
« Reply #1 on: September 29, 2016, 07:52:50 PM »
Thanks for posting the info and pictures. I always wondered what was inside and the approach they took.

Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #2 on: September 29, 2016, 08:27:58 PM »
Thanks for posting the info and pictures. I always wondered what was inside and the approach they took.
I always wondered too, so I was glad to get the opportunity to check it out! I could never find anything about it online.

Offline Cutty Sark Sailor

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Re: Inside the Boltek antenna
« Reply #3 on: September 29, 2016, 09:04:42 PM »
Just lookin' at it, and brainstormin', it appears to have 2 H (M) Field ferrite loops: one Horizontal plane loop, and one vertical plane... (We assume signal polarity as the plane of the impulse E field component). The physical "horizontal' ferrite would be for H (M) field detection of 'Vertically polarized impulses' , and would be 'bi-directional' at right angles to its axis, e.g. "N/S", but weak or null on "E/W" (along the axis) ... the 'Physical Vertical' antenna would be after the H (M) Components of any 'horizontally' polarized sferics... would be Omni directional, and may also contribute somewhat to "E" components of an impulse....
 
 

Offline miraculon

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Re: Inside the Boltek antenna
« Reply #4 on: September 30, 2016, 08:32:34 AM »
Just lookin' at it, and brainstormin', it appears to have 2 H (M) Field ferrite loops: one Horizontal plane loop, and one vertical plane... (We assume signal polarity as the plane of the impulse E field component). The physical "horizontal' ferrite would be for H (M) field detection of 'Vertically polarized impulses' , and would be 'bi-directional' at right angles to its axis, e.g. "N/S", but weak or null on "E/W" (along the axis) ... the 'Physical Vertical' antenna would be after the H (M) Components of any 'horizontally' polarized sferics... would be Omni directional, and may also contribute somewhat to "E" components of an impulse....

Ummm, Cutty the Boltek antenna/amp module itself is mounted such that the connector is "down", hence both ferrites are "horizontal".



The PCB photo has the plane of the board horizontally, so this probably was a source of confusion.

Anyways, many thanks to JupiterJoe for the "equipment autopsy". I too was very curious about what was in the innards of this thing. It looks like they have many wire turns around the ferrite rods, even though they are short ones as necessitated by the module enclosure. I am not sure I like the idea of the end axis of the one solenoid inductor being so close to the other...

Greg H.


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Offline miraculon

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Re: Inside the Boltek antenna
« Reply #5 on: September 30, 2016, 08:36:45 AM »
I see inductors and the passive SMT parts, but are there op-amps on the other side of the PCB? It might be interesting to see what amplifiers they use. If you could post a couple of photos of the other side of the board, including a close-up of the IC part numbers it would be great. Thanks.

Greg H.


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Offline graculus

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Re: Inside the Boltek antenna
« Reply #6 on: September 30, 2016, 11:02:07 AM »
Ummm, Cutty the Boltek antenna/amp module itself is mounted such that the connector is "down", hence both ferrites are "horizontal".

There should be a third sense/phasing antenna in there too which resolves the directional ambiguity of the two ferrites. IIRC It used to be a horizontal plate (maybe just metal foil) that sat above the ferrites.

Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #7 on: September 30, 2016, 12:22:23 PM »
I see inductors and the passive SMT parts, but are there op-amps on the other side of the PCB? It might be interesting to see what amplifiers they use. If you could post a couple of photos of the other side of the board, including a close-up of the IC part numbers it would be great. Thanks.

Greg H.
Here ya go. There is some damage to some components and board itself while removing the plastic(sorry about that, it was a real pain), but you get the idea. The black blob of plastic in the middle won't come off, so I'm unsure if there's anything else other than the components you see on the rest of the board(maybe a controller chip?). The back side of the board is bare. And I don't think there was any other antenna above the other two. They were right at the edge of the plastic box.




Offline miraculon

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Re: Inside the Boltek antenna
« Reply #8 on: September 30, 2016, 01:02:50 PM »
Hmmm...
It looks like there might be some kind of active device under the glob.
Thanks for the pics.
It would probably take some kind of commercial potting remover to get it off. You did a great job without it.

Greg H.


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Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #9 on: September 30, 2016, 01:03:39 PM »
Well, looking closer at the plastic chunk, I saw there were components that were broken off while removing the plastic.


They turned out to be a square metal thing with three leads coming out of it, and a capacitor.




Here's where they would go on the board:



Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #10 on: September 30, 2016, 01:05:55 PM »
Hmmm...
It looks like there might be some kind of active device under the glob.
Thanks for the pics.
It would probably take some kind of commercial potting remover to get it off. You did a great job without it.

Greg H.
If anything, I've learned that this unit is well protected!!! It's a pain to get in for sure.
I'll try to get under that plastic though. Now I'm very interested to find out!
And thanks for telling me it was called potting. I never knew that. It's some sort of epoxy?
« Last Edit: September 30, 2016, 01:20:09 PM by JupiterJoe »

Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #11 on: September 30, 2016, 01:23:38 PM »

There should be a third sense/phasing antenna in there too which resolves the directional ambiguity of the two ferrites. IIRC It used to be a horizontal plate (maybe just metal foil) that sat above the ferrites.

I didn't see any plate, unless it was pulled off, but there is a wide strip of copper that runs to the left and above the antennas on the board. Like an upside down "L".
You can see it here, on the bottom and on the left side:
« Last Edit: September 30, 2016, 01:27:39 PM by JupiterJoe »

Offline Cutty Sark Sailor

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Re: Inside the Boltek antenna
« Reply #12 on: September 30, 2016, 02:05:53 PM »

Ummm, Cutty the Boltek antenna/amp module itself is mounted such that the connector is "down", hence both ferrites are "horizontal".



The PCB photo has the plane of the board horizontally, so this probably was a source of confusion.
Greg H.

#-o  Duh... :oops:
 

Offline graculus

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Re: Inside the Boltek antenna
« Reply #13 on: September 30, 2016, 03:29:06 PM »
I didn't see any plate, unless it was pulled off, but there is a wide strip of copper that runs to the left and above the antennas on the board. Like an upside down "L".

That'll be the third antenna  :-)  This is a Watson Watt loop system, see page 5 in this.

Great job dissecting and documenting it Joe   =D>  I saw one x-rayed some years ago.

Offline miraculon

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Re: Inside the Boltek antenna
« Reply #14 on: September 30, 2016, 03:40:16 PM »
Hmmm...
It looks like there might be some kind of active device under the glob.
Thanks for the pics.
It would probably take some kind of commercial potting remover to get it off. You did a great job without it.

Greg H.
If anything, I've learned that this unit is well protected!!! It's a pain to get in for sure.
I'll try to get under that plastic though. Now I'm very interested to find out!
And thanks for telling me it was called potting. I never knew that. It's some sort of epoxy?

If you "google" for "potting compound" you will find all kinds of it on line. There are epoxy based types, others are jelly-like. It depends on the application. The Failure Analysis guy where I used to work had chemicals that could strip the potting without damaging the parts.

Greg H.


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Offline miraculon

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Re: Inside the Boltek antenna
« Reply #15 on: September 30, 2016, 03:51:41 PM »
Well, looking closer at the plastic chunk, I saw there were components that were broken off while removing the plastic.

They turned out to be a square metal thing with three leads coming out of it, and a capacitor.


It looks like a lot of parts were embedded in the potting and were ripped right off the PCB. I see SMT inductors, capacitors, resistors and what appears to be a SOT23 transistor (They turned out to be a square metal thing with three leads coming out of it) that were caught up in the potting. Kind of like the Jurassic Park mosquito in the amber.

I was sort of expecting to see some Op-Amps (8-lead SOIC packages) or the like, but it doesn't seem to have any.

Greg H.


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Offline graculus

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Re: Inside the Boltek antenna
« Reply #16 on: September 30, 2016, 05:25:39 PM »
On the opposite side of the connector to the electrolytic, looks like that was a chip on a thick leadframe. Voltage reg or power transistor?

Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #17 on: September 30, 2016, 06:12:26 PM »
That'll be the third antenna  :-)  This is a Watson Watt loop system, see page 5 in this.

Great job dissecting and documenting it Joe   =D>  I saw one x-rayed some years ago.
Very cool! Thank you for the link. Very informative.

Thanks man. I wish I could have been more gentle with it, It was prying off nice and easy at first, then popped right off! :/ I cooked it in the oven at 500 for a while, and that made the potting brittle and it came apart much easier. I was never able to find any technical info about it online, so when I got the chance, I was all over it. :) Yeah, I was the kid that took everything apart in the house to see how it worked... :)

Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #18 on: September 30, 2016, 06:17:15 PM »
On the opposite side of the connector to the electrolytic, looks like that was a chip on a thick leadframe. Voltage reg or power transistor?
Miraculon thinks it may be a SOT23 transistor. I looked it up online and agree that's what it looked like. Maybe something like what's attached below...

Offline graculus

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Re: Inside the Boltek antenna
« Reply #19 on: September 30, 2016, 06:59:22 PM »
Miraculon thinks it may be a SOT23 transistor. I looked it up online and agree that's what it looked like. Maybe something like what's attached below...

I think it's much bigger than that. That copper base plate looks to be about 8mm wide, but an SOT23 package is only 3mm wide. Could be something like an SOT-263. Something in those antennas runs hot, and I'm guessing this is it.

Offline JupiterJoe

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Re: Inside the Boltek antenna
« Reply #20 on: September 30, 2016, 07:11:36 PM »
Ahhhhh, you're probably right. The 3 leads are all on the same side like shown in the picture. It's cool to know what's in there. Thanks to you guys, I have an idea! :)

Miraculon thinks it may be a SOT23 transistor. I looked it up online and agree that's what it looked like. Maybe something like what's attached below...

I think it's much bigger than that. That copper base plate looks to be about 8mm wide, but an SOT23 package is only 3mm wide. Could be something like an SOT-263. Something in those antennas runs hot, and I'm guessing this is it.

Offline miraculon

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Re: Inside the Boltek antenna
« Reply #21 on: October 01, 2016, 08:26:22 AM »
Miraculon thinks it may be a SOT23 transistor. I looked it up online and agree that's what it looked like. Maybe something like what's attached below...

I think it's much bigger than that. That copper base plate looks to be about 8mm wide, but an SOT23 package is only 3mm wide. Could be something like an SOT-263. Something in those antennas runs hot, and I'm guessing this is it.

You might be right. The size of the electrolytic puts it into that range, plus the tab looks more like the SOT-263.
It might be a pass transistor for a voltage regulator. I still would like to know what is used for amplifiers....

Greg H.


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Offline graculus

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Re: Inside the Boltek antenna
« Reply #22 on: October 01, 2016, 10:47:22 AM »
You might be right. The size of the electrolytic puts it into that range, plus the tab looks more like the SOT-263.
It might be a pass transistor for a voltage regulator. I still would like to know what is used for amplifiers....

Greg H.

I was comparing it to the connector, an "RJ45" plug is 12 mm wide. I think the black blob in the middle of the board may have been the amp location. There are less turns on the ferrites than I would have guessed  :?

Offline C5250

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Re: Inside the Boltek antenna
« Reply #23 on: October 10, 2016, 10:23:48 PM »
Thanks man. I wish I could have been more gentle with it, It was prying off nice and easy at first, then popped right off! :/ I cooked it in the oven at 500 for a while, and that made the potting brittle and it came apart much easier. I was never able to find any technical info about it online, so when I got the chance, I was all over it. :) Yeah, I was the kid that took everything apart in the house to see how it worked... :)

There are many different encapsulating compounds and trying to figure out any specifics of what one was used is nearly impossible. It is possible to remove some of them with the right chemical and/or heat, or at least soften it up. The usual stuff didn't have much effect on that rock hard stuff Boltek uses, so I didn't go to far with my attempt.
 
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