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September 23rd 03, 04:59 AM

In article , mike
writes:

On 22 Sep 2003 01:32:08 GMT, (Avery Fineman)
wrote:

A small neon bulb was used in thousands of ARC-5 Command Set
receivers in WW2 for static bleed-off. Similar to an old NE-2 bulb.
No need to use a resistor. The neon will conduct somewhere around
70 Volts and shunt any static pickup to ground...then goes into non-
conducting state until the next static potential build-up.

Wow.....70 volts seems a tad high to be protective in my solid state
portable. I suspect the older vacuum tube sets were far more static
resistant. I've read the limit for my sony portable should be kept
below 0.7volts to keep the sensitive front end electronics safe.

You can use practically anything modern in the way of diodes there
but the high-speed types such as 1N914 and 1N4148 are very cheap
and available many places. Varistors could be used (GE "movisters")
or even 1N4000 series rectifier diodes. Diodes have a 0.6 to 0.7 VDC
forward conduction voltage if silicon.

Put them side by side with the anode of one to the cathode of the
other at each end. That will limit voltage input to about 1.4 V peak-to-
peak. You could put a small series resistor, say 22 Ohms or so,
between antenna input and the diodes to limit peak diode current on
conduction. Your option...since the series resistor will drop the RF
input level slightly.

You could also use a high-inductance RF "choke" in place of diodes
and neon bulb. 1 to 5 mHy would work at HF bands. That forms a
constant low-resistance DC path from antenna to ground and keeps
static accumulation bled off immediately.

Len Anderson
retired (from regular hours) electronic engineer person

I've read suggestions for resistors ranging from 2.2 k ohms to 56 k
ohms all the way up to 100 k ohms. The most recent information being
the lowest value resistors. From the schematics I have seen, the
resistors were placed in parralel between the antenna input and ground
input. Or in the case of a two wire unbalanced input, between each
wire and the case of the tuner which is grounded.

Guess I might have to just play resistor values and see what doesnt
hurt signal strenth (another suggestion I read).

good information though, thanks. - mike