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...

Thanks,

Dave

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...

Thanks,

Dave

This was fairly common in WWII era radios.

A NE-2 fires at around 90-110V, which is more than a lot of solid state
equipment can handle, so the protection offered is dubious with modern radios.

That said, it certainly can't hurt anything to try it if you have some
weird problem with static.

You can still get them, but probably not locally.

Jameco (http://www.jameco.com/) still carried them last I looked.

To see where a particular bulb actually fires, put the bulb in parallel with
a capacitor and feed it with around a 100V or so DC though a resistor of
a few K.

You will have built a relaxation oscillator. The larger the cap and/or resistor,
the lower the flash rate.

If you don't have a 'scope to measure the voltage, increase the resistor
size until the flash rate is slow enough to watch the cap charge with a
voltmeter.

--
Jim Pennino

Remove .spam.sux to reply.

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

wrote:
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...

Thanks,

Dave

This was fairly common in WWII era radios.

A NE-2 fires at around 90-110V, which is more than a lot of solid state
equipment can handle, so the protection offered is dubious with modern radios.

That said, it certainly can't hurt anything to try it if you have some
weird problem with static.

You can still get them, but probably not locally.

Jameco (http://www.jameco.com/) still carried them last I looked.

To see where a particular bulb actually fires, put the bulb in parallel with
a capacitor and feed it with around a 100V or so DC though a resistor of
a few K.

You will have built a relaxation oscillator. The larger the cap and/or resistor,
the lower the flash rate.

If you don't have a 'scope to measure the voltage, increase the resistor
size until the flash rate is slow enough to watch the cap charge with a
voltmeter.

I should have added that you can't use the neon if there is a transmitter
attached to the same line.

--
Jim Pennino

Remove .spam.sux to reply.

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...

Thanks,

Dave

This was fairly common in WWII era radios.

A NE-2 fires at around 90-110V, which is more than a lot of solid state
equipment can handle, so the protection offered is dubious with modern
radios.

That said, it certainly can't hurt anything to try it if you have some
weird problem with static.

You can still get them, but probably not locally.

Jameco (http://www.jameco.com/) still carried them last I looked.

To see where a particular bulb actually fires, put the bulb in parallel
with
a capacitor and feed it with around a 100V or so DC though a resistor of
a few K.

You will have built a relaxation oscillator. The larger the cap and/or
resistor,
the lower the flash rate.

If you don't have a 'scope to measure the voltage, increase the resistor
size until the flash rate is slow enough to watch the cap charge with a
voltmeter.

--
Jim Pennino


Thanks for the reply, Jim.

While waiting I set up a charging system for a cap and then tested to see
whether the bulb would discharge the cap. No go. I am sure that at a high
enough voltage the bulb might help, but I am going to have to use a resistor
in parrallel with the bulb, or some other setup, to guard against relatively
low voltage static buildup.

Thanks for the relaxation osc. idea. I might actually use that in m search.
Never would have thought of it.

Much appreciated...

Dave

"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

wrote in message
...
wrote:
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...

Thanks,

Dave

This was fairly common in WWII era radios.

A NE-2 fires at around 90-110V, which is more than a lot of solid state
equipment can handle, so the protection offered is dubious with modern
radios.

That said, it certainly can't hurt anything to try it if you have some
weird problem with static.

You can still get them, but probably not locally.

Jameco (http://www.jameco.com/) still carried them last I looked.

To see where a particular bulb actually fires, put the bulb in parallel
with
a capacitor and feed it with around a 100V or so DC though a resistor of
a few K.

You will have built a relaxation oscillator. The larger the cap and/or
resistor,
the lower the flash rate.

If you don't have a 'scope to measure the voltage, increase the resistor
size until the flash rate is slow enough to watch the cap charge with a
voltmeter.

I should have added that you can't use the neon if there is a transmitter
attached to the same line.

--
Jim Pennino


No problem, no transmitter here. Receiver only.

Thanks.

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