[MRCA] project luck or lack thereof

[W2HX]

Dang! See? Just goes to show you sharing your failures with others can help you succeed. Both Jeep and Mike KC4TOS hit the nail on the head. Instead of just checking continuity, I measured resistance. And lo and behold, 74k ohms from solder terminal to center contact. I had no idea that that domed/vs flat indicated incandescent vs neon!

Based on this 74k measurement, does that indicate what kind of neon bulb I should look for? The bulb base is T3-1/4.  What do I look for?
Looks like I could salvage this after all!
Thanks Jeep and Mike


From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of Doran Platt
Sent: Thursday, September 3, 2020 5:50 AM
To: Military Radio Collectors Association <mrca at mailman.qth.net>
Subject: Re: [MRCA] project luck or lack thereof

I have been snookered in the past with these lamp holders.   Some have built-in series resistors for neon lamps. If the lamp contact appears domed, it is probably the neon type.  If flat, probably incandescent.  Maybe?
Jeep K3HVG
On 09/02/2020 7:59 PM W2HX <w2hx at w2hx.com<mailto:w2hx at w2hx.com>> wrote:


Hi friends.

Just a story about how gremlins sometimes get into the simplest of projects.  I’ve been working on an antenna switching system for my shack. The project has evolved over time. Originally it was to switch one antenna amongst two different couplers at the antenna location.  One for transmitters up to 400W (RF-382A) and the other for my 1KW transmitters (Sunair 1KW coupler).

I have since swapped out both of those couplers for one Rohde and Schwarz 1KW coupler that takes tune power from 50W through 300W (or thereabouts) so now I only need one coupler for all my radios.   And instead of switching couplers, I will switch antennas. One vertical and one horizontal long wire, both will share the coupler and the counterpoise radials.

I started really buckling down to finish this project and part of it was making a 19” control panel to enable power to the antenna site and handle the switching and other functions. I assembled the parts, most from my parts bin. One part was a nice 120V pilot lamp which I thought was a good thing to add so I can see that the power to the antenna site is on or off. I found a brand new, unused indicator lamp housing with jewel top in my parts bin that would be perfect. I probably bought this light at a hamfest 10 years ago, but who remembers.

The panel had lots of things to be mounted on it including some barrier strips for wiring etc so I figured I would get the panel created at front panel express. They provide a simple cad tool and you upload your drawing and voila, about 10 days later the panel arrives at your home all done to your specifications. Not cheap but considering the time it would take and the mistakes I was sure to make it seemed a good idea (and it was). For example, the fuse holder I was going to use needed a “D” hole which I could never make myself at home, so there you go. Among many others, I defined the hole for the pilot lamp in the cad drawing. The panel arrived as scheduled.

Well today I started wiring up the AC. And did a simple test, when I throw the AC power switch does my little pilot lamp illuminate? No! why not?! Such a simple thing! Fuse was there, switch was switching, not much to go wrong. Must have been the lamp, of course. I had to find this little bayonet lamp for 120V and low wattage that would fit this holder. Checked out the lamp, it is continuous no problem!? What’s going on here? Well I ohmed out every single wire.

The problem? The lamp holder had no continuity from one terminal to the center conductor! I couldn’t believe it! I pushed it in really tried to make contact with my DVM and nothing. Who would expect a brand new item, one that is so simple to fail!.  Arrggh. So now to find another one with the same diameter as the original so it will properly fit in my panel that I took such pains to create.

Anyway. Very long story. I hope it wasn’t too boring, but you know. You have to build up these stories to make the climax more satisfying hihi.

73 Eugene W2HX
Keep your lamps trimmed and burning

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