John Smith wrote:
flashdrive wrote:

...
Has anyone ever successfully reverse engineered the pre-amp of a
Wellbrook loop? It might be possible to dissolve the encapsulating
material (epoxy?) to reveal the PCB and componants. Otherwise a
medical scanner (seriously) might reveal some useful information.

My question would be, "Why go to the trouble?"

Indeed, grab a DC - 1Ghz MMIC device (make sure you don't get an SMC
component, unless you like soldering under a microscope), stick a proper
filter for the freqs/bands in front of it, and feed its' input with a
well designed loop ... if you need EXTREME gain, you can cascade a
couple of MMICs.

Regards,
JS

I do SMD rework occasionally, with MagEyes. You'd use a power amplifier
for a pre-amp?

Dave wrote:

...
I do SMD rework occasionally, with MagEyes. You'd use a power amplifier
for a pre-amp?

For some? ABSOLUTELY!

Like, is the loop completely shielded? How efficient of a loop are we
speaking of? Etc.

But in all cases, yeah, I would provide for much more amplification
factor than I will ever need, why not? I mean, do I really need the 454
with blower in my "toy car?"

Regards,
JS

In article ,
Dave wrote:

John Smith wrote:
flashdrive wrote:

...
Has anyone ever successfully reverse engineered the pre-amp of a
Wellbrook loop? It might be possible to dissolve the encapsulating
material (epoxy?) to reveal the PCB and componants. Otherwise a
medical scanner (seriously) might reveal some useful information.

My question would be, "Why go to the trouble?"

Indeed, grab a DC - 1Ghz MMIC device (make sure you don't get an SMC
component, unless you like soldering under a microscope), stick a proper
filter for the freqs/bands in front of it, and feed its' input with a
well designed loop ... if you need EXTREME gain, you can cascade a
couple of MMICs.

Regards,
JS

I do SMD rework occasionally, with MagEyes. You'd use a power amplifier
for a pre-amp?

SMD is best for RF but small through lead components on a PCB should be
OK for HF work. Depending on SMD size of the components I use 4X to 10X
magnification.

I agree with Smith, design your own stuff besides how well things work
depends as much on how circuits are physically built or laid out. The
encapsulate is for weather protection not for defeating copying.

--
Telamon
Ventura, California