On Sat, Apr 19, 2025 at 02:27 PM, Tom W8JI wrote:
I converted a lot of my sweep tube stuff to 6146's over the years, including Swans and Drake T4XCs. It was a natural thing to do given the tubes back then.
The original Navigator meter was what we called a "wiggler" at Prime Instruments. Most of the 1 mA meters like that we made were in the 1000 ohm or 1 volt FS range. The 10mA would have been around 100 ohm coils, still in the 1V range.
What was the original Navigator plate shunt? Was it 33 ohms or 3.3 ohms? My schematic copy is not clear.?
3.3 ohms would have been .24*3.3? = .792V or 79.2 ohm movement resistance with a 10mA meter. That sounds about like the meters we made. A 10mA wiggler was typically in the 100-ohm coil resistance range.
We manufactured meters like that at Prime. Our total bill of material was something like 50 cents in 1980 for an out the door meter but we made truckloads of them. Not the best meter in the world. We put a dot of silicone oil in the jewel to stop the bounce high torque light weight movements and pointers typically have. A different viscosity for different damping.? :)
73 Tom
The original shunt was 33 ohms.? Mine measured 36.7 ohms.? Your comment about the silicone oil to stop the bounce is something I never heard before.? Maybe this original meter had the same treatment but the oil migrated out of the movement or dried up over the years.? If I ever run into that type of problem again, I'll give the oil treatment a try.? I wonder how the internal meter construction on the Navigator meter differs from higher quality meters.? I've run into the same bouncing needle problem a couple of times in the past with Tentec Centurion amplifiers.??
?
73, Floyd - K8AC
Floyd - K8AC