Test the bulb tuning by loading into a high resistance such as a 5K   resistor.
K4CHE


On 11/20/2024 3:30 PM, comcast via Milsurplus wrote:
guys I could never get my bulb to glow bright  while tuning up even after changing the bulb twice from other sets I was using the dipole.  not sure if it had to do with low impedance 75 ohm antenna   Jeff

Sent from my iPhone

On Nov 20, 2024, at 11:52 AM, Rob Flory <[email protected]> wrote:


RTFM

On Wed, Nov 20, 2024 at 10:49 AM Ray Fantini via MRCA <[email protected]> wrote:

More GRC-9 questions! What type Neon bulb is I101, that’s the neon bulb that you tune to max. Think it’s a NE-47 but not certain.

 

Commentary and opinion beyond this point, if easily offended do not read!

Ok, I get it that you needed some method to tune to max, the old WW2 stuff always used a antenna current meter and for some reason in the fifties there was by cost cutting or because of size restrictions the idea of using a neon bulb to tune to max bulb. These are field radios, to be used in the field or attached to a vehicle for use in the field. How in the Hell where you supposed to see this little neon light in the daylight?

Ok, so maybe the big black tube around the bulb helps and will admit that until I started this project never used a GRC-9 before, although I now have like five of them in the shop all at once but just looking at it have to wonder how that was supposed to be used. Speculation is that you would drag out a field strength meter and tune the radio that way. Just using vertical output have no issues generating power into a fifty ohm load and inside with the one good neon bulb I see it ok but already know where you set the antenna tuning control has a big difference in output power and with a week display like the original design have to wonder how this is used outside in the daytime?

 

Ray F/KA3EKH

 

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