Sir Planigan. . . .
In the words of olde tyme radio's . . . Distinguished and esteemed Red Skelton . . . . and in using his "Junior, the mean wittle kid personna" . . .
'Dat joost don't sound right to me . . .NOOOOOO . . . . . 'DAT JOOST DON'T SOUND RIGHT TO ME !
And of course, that being in respect to the association of the initial statement of:
Evolution: The evolution of the diode just ended up with germanium being the primary most popular semiconductor to be used Also there is the junction voltage threshold of initially starting conduction in the 200's of millivolts on the germanium semiconductor materiel, while its up in the ~550-700 millivolts on the silicon diode. Next ?
I have a 150 EICO Signal (solid state) and it calls for an RF Probe with a diode and a 1 Meg resistor.
but . . . .but . . . .BUT . .BUT . .BUT, the Eico 150 is a signal TRACER.
First there was the fire charred, and then pointed stick . . and then the evolution of the refined stone, and then later, metal tipped spear . . . .
when sealed up and being a fixed diode semiconductor unit. Then, the evolution of the silicon diode a bit later in time.
The germanium unit has its temperature affected back resistance . . .leakage . . . and simultaneously, that infinitely lesser,
almost non existant effect upon a silicon type of unit.
Also, there is the voltage handling specs, with the capability of the silicon diode to be able to withstand hundreds of volts of back EMFvoltage.
The germanium unit would only be able to handle decades of back EMF voltage without leakage or breakdown.
THAT means that a hefty 550-700 millivolt threshold must be met on the RF input into a germanium unit, while a much weaker
200 mv inputted level would already be conducting on a germanium unit.
In your situation of the use of that diode for initial RF detection, that would be of major significance when dealing with a feeble RF input signal,(antenna coil input) but, if you had a hefty RF signal being involved,(amplified I.F.strip signal) that would be of less significance.
The other aspect would be the inherent internal design of the diode infrastructure and its desired end use.
In the case of the invenerable 1N4XXX series they are having the semiconductor junction faces spread out across a wiiiide area,
since they are also having to consider current dissipation, and need of that for heat dissapation and the handling of same.
On the RF situation, only the minutest contact area is required, therefore that lower interelectrode capacitance will be even MORE optimal at its RF handling aspect.
Soooooooo, your best bet in that probe's diode, from the weak input signal aspect, would be the utilizaton of one of the old family of 1N34, 1N60, 1N64,1N90 or 1N270 germanium diodes . . . .or one of the new generation of Schottky barrier / hot carrier / mixer diodes. . .a common, popular example, being a Hewlett Packard 1N5711 which also exhibits excellent RF characteristics, along with a lower voltage sensitivity threshold.
Another unit which might be questioned is the 1N914 / 1N4148 family of silicon switching diode (gazillllions made, and in use), which has all of the good RF and nil leakage aspect of silicon diodes, BUTTTT is still hindered with that monumental initial voltage threshold , should you be working with miniscule RF input levels.
73's de Edd
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:
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:Sir Planigan. . . .
:
:
:
:In the words of olde tyme radio's . . . Distinguished and esteemed Red Skelton . . . . and in using his "Junior, the mean wittle kid personna" . . .
:
:
:'Dat joost don't sound right to me . . .NOOOOOO . . . . . 'DAT JOOST DON'T SOUND RIGHT TO ME !
:
:
:And of course, that being in respect to the association of the initial statement of:
:
:
:
:
:I have a 150 EICO Signal (solid state) and it calls for an RF Probe with a diode and a 1 Meg resistor.
:
:
:
:
:but . . . .but . . . .BUT . .BUT . .BUT, the Eico 150 is a signal TRACER.
:
:
:
:Evolution:
:
:
:First there was the fire charred, and then pointed stick . . and then the evolution of the refined stone, and then later, metal tipped spear . . . .
:
:
:
:The evolution of the diode just ended up with germanium being the primary most popular semiconductor to be used
:when sealed up and being a fixed diode semiconductor unit. Then, the evolution of the silicon diode a bit later in time.
:
:
:The germanium unit has its temperature affected back resistance . . .leakage . . . and simultaneously, that infinitely lesser,
:almost non existant effect upon a silicon type of unit.
:
:
:Also, there is the voltage handling specs, with the capability of the silicon diode to be able to withstand hundreds of volts of back EMFvoltage.
:
:
:The germanium unit would only be able to handle decades of back EMF voltage without leakage or breakdown.
:
:
:
:Also there is the junction voltage threshold of initially starting conduction in the 200's of millivolts on the germanium semiconductor materiel, while its up in the ~550-700 millivolts on the silicon diode.
:
:
:THAT means that a hefty 550-700 millivolt threshold must be met on the RF input into a germanium unit, while a much weaker
:200 mv inputted level would already be conducting on a germanium unit.
:
:
: In your situation of the use of that diode for initial RF detection, that would be of major significance when dealing with a feeble RF input signal,(antenna coil input) but, if you had a hefty RF signal being involved,(amplified I.F.strip signal) that would be of less significance.
:
:
:
:
:The other aspect would be the inherent internal design of the diode infrastructure and its desired end use.
:
:
:In the case of the invenerable 1N4XXX series they are having the semiconductor junction faces spread out across a wiiiide area,
:since they are also having to consider current dissipation, and need of that for heat dissapation and the handling of same.
:On the RF situation, only the minutest contact area is required, therefore that lower interelectrode capacitance will be even MORE optimal at its RF handling aspect.
:
:
:Soooooooo, your best bet in that probe's diode, from the weak input signal aspect, would be the utilizaton of one of the old family of 1N34, 1N60, 1N64,1N90 or 1N270 germanium diodes . . . .or one of the new generation of Schottky barrier / hot carrier / mixer diodes. . .a common, popular example, being a Hewlett Packard 1N5711 which also exhibits excellent RF characteristics, along with a lower voltage sensitivity threshold.
:
:
:Another unit which might be questioned is the 1N914 / 1N4148 family of silicon switching diode (gazillllions made, and in use), which has all of the good RF and nil leakage aspect of silicon diodes, BUTTTT is still hindered with that monumental initial voltage threshold , should you be working with miniscule RF input levels.
:
:
:
:
:
:Next ?
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:
:
:
:
:
:73's de Edd
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