On Dec 23, 9:46*am, PJ wrote:
Folks,

I have purchased a Sangean ATS-909 World Receiver. It is equipped with
an internal ferrite antenna för MW and LW, and a telescope antenna for
SW and FM. It also comes with a portable SW antenna (ANT-60), seven
meters long. Is this external antenna generally sufficient for SW
reception, or should I get a different antenna? If yes, is there a
solution that doesn't cost all that much money? I have a copy of the
2009 World Radio TV Handbook, and they are talking about a Wellbrook
ALA-1530+ loop antenna, and let me tell you, that one is well past my
budget, because it costs $466... I am looking for something a lot
cheaper... :-) If it is recommended to replace the ANT-60, that is.

PJ

http://www.wellbrook.uk.com/ALA100b.html
With a bit of hacking, the Wellbrook ALA 100 is as good as any of the
shortwave antennas they sell. It is just the amplifier. You have to
roll your own loop. The ALA100 is the lowest cost welbrook. At the
current exchange rate, the ala100 is a over $200.

I have made a few loops with this amp. I have a 2ftx2ft out of copper
pipe for direction finding. I have 4ft x 6ft copper pipe for regular
use. It's really stupid big and will eventually be reduced to the
original 4ftx4ft. I have a few portable designs that are around 40ft
worth of wire.

The wellbrook loops are just amazing. All that said, the ATS909
probably can't handle that much signal. It would make sense to use
one with a portable shortwave radio.

wrote:

http://www.wellbrook.uk.com/ALA100b.html
With a bit of hacking, the Wellbrook ALA 100 is as good as any of the
shortwave antennas they sell. It is just the amplifier. You have to
roll your own loop. The ALA100 is the lowest cost welbrook. At the
current exchange rate, the ala100 is a over $200.

I have made a few loops with this amp. I have a 2ftx2ft out of copper
pipe for direction finding. I have 4ft x 6ft copper pipe for regular
use. It's really stupid big and will eventually be reduced to the
original 4ftx4ft. I have a few portable designs that are around 40ft
worth of wire.

The wellbrook loops are just amazing. All that said, the ATS909
probably can't handle that much signal. It would make sense to use
one with a portable shortwave radio.

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.

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

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

John Smith wrote:
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

And, certainly, I am assuming, you are using "power amplifier" in
correct context, when dealing with low power devices--as opposed to the
5kw POWER AMPLIFIER behind, and NOT in front of, my rig?

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