Dave wrote:
I saw somewhere that you could use an NE-2 bulb between the antenna "hot"
lead and ground as a static discharge device for a receiver, but can't find
an NE-2 and don't know anything about neon bulbs. Anybody know if a
standard neon bulb rated at 125 VAC could be used in this manner? Or how I
could test it? I'm thinking about charging up a 50V electrolytic capacitor
and hitting the bulb with that, to see if it discharges the cap. I have a
..22uF 630V mylar cap between the antenna and the input to the tuner because
the 35V disc I had there got blown, so I know that static can be a problem
with my setup even though it is grounded at two points.
Would welcome any ideas anyone has on how to make this work...
============================================
To avoid building-up of static you can fit a say 47 Kilo Ohms
non-inductive resistor between what you call the 'hot' lead and earth.
This would not affect the received or transmitted signal.

I have fitted 2 non-inductive (carbon) 1 Watt resistors (47 KOhms) from
the incoming balanced feeder to earth at the Antenna Matching Unit.
This approach is obviously also OK with an incoming coax feeder.
At 100 W RF output the voltage would be 71 V at the transceiver. This
would dissipate a little over 0.1 Watt in the 47K resistor fitted at the
transceiver. Metal-oxyde resistors can for this purpose also be
considered as non-inductive.


Frank GM0CSZ / KN6WH

"Highland Ham" wrote in message
...
Dave wrote:
I saw somewhere that you could use an NE-2 bulb between the antenna "hot"
lead and ground as a static discharge device for a receiver, but can't
find an NE-2 and don't know anything about neon bulbs. Anybody know if a
standard neon bulb rated at 125 VAC could be used in this manner? Or how
I could test it? I'm thinking about charging up a 50V electrolytic
capacitor and hitting the bulb with that, to see if it discharges the
cap. I have a ..22uF 630V mylar cap between the antenna and the input
to the tuner because the 35V disc I had there got blown, so I know that
static can be a problem with my setup even though it is grounded at two
points.
Would welcome any ideas anyone has on how to make this work...
============================================
To avoid building-up of static you can fit a say 47 Kilo Ohms
non-inductive resistor between what you call the 'hot' lead and earth.
This would not affect the received or transmitted signal.

I have fitted 2 non-inductive (carbon) 1 Watt resistors (47 KOhms) from
the incoming balanced feeder to earth at the Antenna Matching Unit.
This approach is obviously also OK with an incoming coax feeder.
At 100 W RF output the voltage would be 71 V at the transceiver. This
would dissipate a little over 0.1 Watt in the 47K resistor fitted at the
transceiver. Metal-oxyde resistors can for this purpose also be
considered as non-inductive.


Frank GM0CSZ / KN6WH

Thanks for the input, Frank. I believe this, or something like it, is what
I am going to have to do. I've already got the bulb installed in the
receiver case, and I guess I'll leave it there to warn me of impending doom,
but the resistor idea is what will probably save my bacon.

Is a metal-oxide resistor the same thing as a metal-film resistor? Or would
that be inductive and mess with my incoming signal?

Thanks much,

Dave

Is a metal-oxide resistor the same thing as a metal-film resistor? Or would
that be inductive and mess with my incoming signal?
=========================
Dave , My apology , I meant indeed metal 'film' resistor.

Frank GM0CSZ / KN6WH

"Highland Ham" wrote in message
...
Is a metal-oxide resistor the same thing as a metal-film resistor? Or
would that be inductive and mess with my incoming signal?
=========================
Dave , My apology , I meant indeed metal 'film' resistor.

Frank GM0CSZ / KN6WH





Aah. Gotcha. Thanks for the ideas and the info.

73

Dave

"Dave" wrote in message
...

"Highland Ham" wrote in message
...
Is a metal-oxide resistor the same thing as a metal-film resistor? Or
would that be inductive and mess with my incoming signal?
=========================
Dave , My apology , I meant indeed metal 'film' resistor.

Frank GM0CSZ / KN6WH





Aah. Gotcha. Thanks for the ideas and the info.

73

Dave



BTW, this brings up another question: I have read that carbon composition
resistors have a small amount of capacitive reactance due to the tiny
particles that make up their mass, and should not be used for RF projects.
But metal film resistors are inductive. So what kind of resistors should I
be using in my RF projects? Is there a third type?

Thanks,

Dave

"Dave" wrote in message
...
Frank GM0CSZ / KN6WH

Thanks for the input, Frank. I believe this, or something like it, is
what I am going to have to do. I've already got the bulb installed in the
receiver case, and I guess I'll leave it there to warn me of impending
doom, but the resistor idea is what will probably save my bacon.

Is a metal-oxide resistor the same thing as a metal-film resistor? Or
would that be inductive and mess with my incoming signal?

Thanks much,

Dave


Why would the inductance be of any concern? It would
be effectively in series with the resistance, thus raising the
device's impedance... I'd think that would lessen the
loading on receive or transmit signals.

Pete

"Uncle Peter" wrote in message
...

"Dave" wrote in message
...
Frank GM0CSZ / KN6WH

Thanks for the input, Frank. I believe this, or something like it, is
what I am going to have to do. I've already got the bulb installed in
the receiver case, and I guess I'll leave it there to warn me of
impending doom, but the resistor idea is what will probably save my
bacon.

Is a metal-oxide resistor the same thing as a metal-film resistor? Or
would that be inductive and mess with my incoming signal?

Thanks much,

Dave


Why would the inductance be of any concern? It would
be effectively in series with the resistance, thus raising the
device's impedance... I'd think that would lessen the
loading on receive or transmit signals.

Pete



Hello Pete,

I was actually thinking something similar, that the diodes would prevent any
current from flowing through the circuit so long as the voltage remained on
the small-signal level. And if a large pulse did come through, the
inductance of the resistors would be the least of my worries. Any
interferrance it caused in my receiver would be brief and likely go
unnoticed. Does this sound plausible, or at least somewhat predictive of
likely real-life events in the case of a static charge coming down the line?

Dave