[Milsurplus] [ARC5] A.C. Modified BC-348

[Jim Whartenby]

I can find no mention of temperature specifications in the BC-348 manuals that I have access to.  I think environmental issues like this didn't become much of a concern until well after WW2.  It would be interesting to compare an unmodified (unholy <grin>) BC-348 to an original six tube hallicrafters S-38.  Which receiver has a hotter top of the case after several hours of operation?  Anyone have a working example of each and an IR thermometer?  
My guess is that the S-38 will run hotter since the top surface area is smaller.  Of course a lot depends on how the BC-348 is powered.  Dynamotor or AC power supply, 6X5 v 5Y3 v solid state for the rectifier.
Why speculate when one can measure?Jim

Too much agreement kills a chat.  E. Cleaver
-----Original Message-----
From: Robert Downs via Milsurplus <milsurplus at mailman.qth.net>
To: arc5 at mailman.qth.net; milsurplus at mailman.qth.net
Sent: Sun, Aug 29, 2021 2:41 am
Subject: Re: [Milsurplus] [ARC5] A.C. Modified BC-348

<!--#yiv6775336799 _filtered {} _filtered {} _filtered {}#yiv6775336799 #yiv6775336799 p.yiv6775336799MsoNormal, #yiv6775336799 li.yiv6775336799MsoNormal, #yiv6775336799 div.yiv6775336799MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:12.0pt;font-family:"Times New Roman", "serif";}#yiv6775336799 a:link, #yiv6775336799 span.yiv6775336799MsoHyperlink {color:blue;text-decoration:underline;}#yiv6775336799 a:visited, #yiv6775336799 span.yiv6775336799MsoHyperlinkFollowed {color:purple;text-decoration:underline;}#yiv6775336799 span.yiv6775336799EmailStyle17 {font-family:"Times New Roman", "serif";color:#0D0D0D;font-weight:normal;font-style:normal;}#yiv6775336799 .yiv6775336799MsoChpDefault {} _filtered {}#yiv6775336799 div.yiv6775336799WordSection1 {}-->I have to comment on the “Unfortunately”, though.  Remember that the original design with no ventilation provided for assumed that the set would spend most of its operating hours above 17,000 feet where the expected ambient temperature is shall we say “chilly”?  Sitting on the ground in San Antonio though, the ambient temperature is more likely to be described as “toasty”.  So ventilation has to be considered as “required”.    Robert Downs  From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] 
Sent: Saturday, August 28, 2021 17:24
To: Hubert Miller
arc5 at mailman.qth.net; milsurplus at mailman.qth.net
Subject: Re: [ARC5] A.C. Modified BC-348  On Fri, Aug 27, 2021 at 11:29 PM Hubert Miller <kargo_cult at msn.com> wrote:
Here's a 348 i found in my stash. The rectifier tube is a 25Z5, which means a drop -in supply with minimum mods. Unfortunately tho, the cabinet top has been aerated. The PS has no markings really except for this on the tube area shield:"TESTED GOOD 11/10/ 45 ROB". Too early to have hit the surplus stores, so this must be a gov't mod.-Hue Miller        Sent from my Verizon, Samsung Galaxy smartphone______________________________________________________________
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