RHF wrote:

DP,

1. When the radio is not being used the POT is set to Zero and the
Receiver's Antenna Input is Shorted-Out and Grounded.

2. This is a 'set' of both Forward and Reverse Diodes Dual [Doubled]

--|--|--

--|--|--

If you have enough wide band RF signal levels to make these dual
diodes work then with a modern solid state radio most likely you have
major front-end overload in the radio.

~ RHF

Didn't they put this same sort of setup in one of the NRD's (JRC) of yore, only to
discover it caused intermod and had to be removed.?


.
.
= = = Dale Parfitt
= = = wrote in message ...
RHF wrote:

JS,

I have used the NE-2 Neon Bulb and 10K Ohm Risistor with my portable
radio Antenna "GIZMOE" Connector Box to protect the external antenna
inputs of several radios.

I have also used a double pairing of Forward & Reverse Diodes to act
as a low voltage shunts along with the NE-2 Neon Bulb as the Higher
Voltage Shunt and the 10K Ohm Resistor for Static Bleed-Off.


Neon tubes "fire" at around 80-110V. Can your front end take this? Older tube rigs
can, not sure I would bet on a FET front end.
A pair of diodes right on the input can be disastrous. They are a nonlinear device,
easily driven into generating all sorts of mixing products- as they are right at the
antenna, everything from local AM, FM and TV will be seen by the diodes.

Dale W4OP

N8KDV wrote:

RHF wrote:

DP,

1. When the radio is not being used the POT is set to Zero and the
Receiver's Antenna Input is Shorted-Out and Grounded.

2. This is a 'set' of both Forward and Reverse Diodes Dual [Doubled]

--|--|--

--|--|--

If you have enough wide band RF signal levels to make these dual
diodes work then with a modern solid state radio most likely you have
major front-end overload in the radio.


They don't have to be driven into conduction just into the square law region.



Didn't they put this same sort of setup in one of the NRD's (JRC) of yore, only to
discover it caused intermod and had to be removed.?


Some years back, an amateur mfg had varicaps tuning a front end filter- IP3 characteristic
was horrible. The next generation got rid of the idea.

Dale W4OP

In article ,
N8KDV wrote:

Dale Parfitt wrote:

RHF wrote:

JS,

I have used the NE-2 Neon Bulb and 10K Ohm Risistor with my portable
radio Antenna "GIZMOE" Connector Box to protect the external antenna
inputs of several radios.

I have also used a double pairing of Forward & Reverse Diodes to act
as a low voltage shunts along with the NE-2 Neon Bulb as the Higher
Voltage Shunt and the 10K Ohm Resistor for Static Bleed-Off.


Neon tubes "fire" at around 80-110V. Can your front end take this? Older
tube rigs
can, not sure I would bet on a FET front end.
A pair of diodes right on the input can be disastrous. They are a nonlinear
device,
easily driven into generating all sorts of mixing products- as they are
right at the
antenna, everything from local AM, FM and TV will be seen by the diodes.

Dale W4OP

Some very good points Dale.

He is more than right. Diodes are used as broadband white noise sources
in test equipment.

--
Telamon
Ventura, California