[MRCA] Mystery Project

[ac2eu at yahoo.com]

 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:  
 
 #yiv1229018458 filtered {}#yiv1229018458 filtered {}#yiv1229018458 filtered {}#yiv1229018458 filtered {}#yiv1229018458 p.yiv1229018458MsoNormal, #yiv1229018458 li.yiv1229018458MsoNormal, #yiv1229018458 div.yiv1229018458MsoNormal {margin:0in;font-size:12.0pt;font-family:sans-serif;}#yiv1229018458 a:link, #yiv1229018458 span.yiv1229018458MsoHyperlink {color:blue;text-decoration:underline;}#yiv1229018458 span.yiv1229018458EmailStyle19 {font-family:sans-serif;color:windowtext;}#yiv1229018458 .yiv1229018458MsoChpDefault {font-size:10.0pt;}#yiv1229018458 filtered {}#yiv1229018458 div.yiv1229018458WordSection1 {}
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

  

From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of scottjohnson1 at cox.net
Sent: Tuesday, September 16, 2025 3:30 PM
To: ac2eu at yahoo.com; 'B. Smith' <smithab11 at comcast.net>; 'Christopher Bowne' <aj1g at sbcglobal.net>
Cc: mrca at mailman.qth.net
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

  

From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of ac2eu--- via MRCA
Sent: Tuesday, September 16, 2025 8:43 AM
To: B. Smith <smithab11 at comcast.net>; Christopher Bowne <aj1g at sbcglobal.net>
Cc: mrca at mailman.qth.net
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?
  


|  | Virus-free.www.avast.com |

   
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20250917/dd7e2dac/attachment.html>