[MRCA] Mystery Project

Wed Sep 17 11:57:52 EDT 2025

 breaking our toys can be an expensive proposition too.
I'm not saying this is the case, but 10 volts on a 6  volt tube can't be a good thing...even if it works for a while.
Maybe some "trust but verify" is in order? If it were me, I would have had the meter probes clipped across the tube heater terminals before I flipped the switch to monitor the voltage.Call me "anal", but that's how I roll.

    On Wednesday, September 17, 2025 at 08:51:08 AM EDT, Ray Fantini via MRCA <mrca at mailman.qth.net> wrote:  

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If it works it works. Think when we reach the point of regarding our toys a museum artifacts and everything has to be as it was or used within narrowly defined specifications  that’s the day I am thru.

Ray F/KA3EKH

From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net>On Behalf Of comcast via MRCA
Sent: Wednesday, September 17, 2025 7:37 AM
To: ac2eu at yahoo.com
Cc: mrca at mailman.qth.net; Mike Feher <n4fs at eozinc.com>
Subject: Re: [MRCA] Mystery Project

Murphy's Laws of Combat Operations

If it's stupid but it works, it isn't stupid

Sent from my iPhone

On Sep 16, 2025, at 11:00 PM, ac2eu--- via MRCA <mrca at mailman.qth.net> wrote:

No one said any of the sort!  Do you know if it was calculated ? Were the voltages across the tube checked?   He didn't say.

The radio may work , but there is a good chance that the tube is either over or under voltage, because the odds of finding a PERFECT bulb match is low.

This is a discussion group, so we are "discussing" the project.

Just sayin'

I had a radio here that someone put the power transformer on the wrong tap and brought it in for "poor performance".

I found that the B+ was low and the tube heaters were running at 4.25Vac. Stuff happens...

On Tuesday, September 16, 2025 at 04:31:15 PM EDT, Mike Feher <n4fs at eozinc.com> wrote:

Seems a lot of you feel that Breck is a JHS student. He probably even then knew all the things mentioned here. I sure did. It worked for him, so, he calculated everything correctly. It was a clever approach for his needs. 73 – Mike

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

908-902-3831

Subject: Re: [MRCA] Mystery Project

Keep in mind that a tungsten filament lamp has 10-12 times the resistance at normal operating temp as it does at room temperature, so can be used as a ballast/ current limiting some applications, but makes a poor dropping resistor.  If it is AC, consider using face to face Zeners rated at the voltage drop needed, if the drop is small, series forward biased diodes can be used similarly.  Make sure the current and power dissipation ratings are not exceeded.

Scott W7SVJ

Subject: Re: [MRCA] Mystery Project

Subbing the filaments with bulbs is a tricky proposition. They have to have the same current rating as the tube or the string voltage will be out of balance. 

Ever see that old trick electricity question about to bulbs in series? One is a 40 watt and the other is a 100 watt. which will be brighter?

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