[ARC5] BC-454-B Power

Mon Jul 19 20:00:16 EDT 2021

First, AFAIK, the only Command receivers built by A.R.C.for 12 to 14 VDC heaters  were the R-148/ARC-5X, which is a 12-14 VDC version of the R-23/ARC-5, and the two RAT receivers which between them cover 13.5 to 27.0 MC.  So no.  And in any case, it would NOT have had a BC-454-B nameplate.

Also, although most of the metal octal tubes (and their glass descendants) do use pins 2 and 7 for the filament connection, the 6SR7, 6SQ7, 12SR7 and 12SQ7 (and their glass equivalents) use pins 7 and 8.  Seems like there may have been another one as well but it doesn’t matter as it wasn’t used in the BC-454.

Robert Downs

From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Al Klase
Sent: Monday, July 19, 2021 09:45
To: arc5 at mailman.qth.net
Subject: Re: [ARC5] BC-454-B Power

Mike,

Don't be a wimp!  Read the Freakin' Schematic!

Pull the tubes and make continuity measurement between the #2 and #7 pins on the various sockets.  You're dealing with three series circuits in parallel.  Shouldn't take but 10 minutes to determine if it's in the original configuration.

Good luck,
Al

On 7/19/2021 9:51 AM, MICHAEL BITTNER wrote:

Not wanting to poke around the underneath to trace the wiring, Instead I measured the cold filament resistance of each tube (not exactly the same for each one) and then did the math for all of these 12-Volt tube filaments in parallel.  It came out to 2 Ohms down to 4 decimal places as I had originally measured at the dynamotor terminals.   So this puppy has either been converted for 12-Volt power (very workmanlike job) or was originally built that way.  Was there ever a factory-built 12-Volt version of the BC-464-B?  Mike, W6MAB 

On July 19, 2021 at 1:58 AM Brian Clarke  <mailto:brianclarke01 at optusnet.com.au> <brianclarke01 at optusnet.com.au> wrote: 

Not such a good idea, Ken.

This idea of substituting 6 V tubes really only works if all the heaters are in parallel. 6SK7, 6K8, 6SR7 all require 6.3 V @ 0.3 A. The 6V6 heater requires 0.45 A.

Further, the 6V6 is not a good match for anode load; a far better match, and available in metal with the same pin-outs as the 12A6 and 6V6, is the 6F6, anode load 7 k Ohm , but heater current 0.7 A.

73 de Brian, VK2GCE

From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Kenneth G. Gordon
Sent: Monday, 19 July 2021 2:24 PM
To: 'MICHAEL BITTNER'; arc5 at mailman.qth.net; Robert P. Meadows
Subject: Re: [ARC5] BC-454-B Power

On 18 Jul 2021 at 21:16, Robert P. Meadows wrote:

> How about checking the wiring against a proper schematic.  Then you will

> know.  First check the tubes.  A quick change to 12v filaments is to install

> 6 v filament tubes…   Not hard R

Use a 6V6 in the 12A6 socket. Base diagrams are identical: 8AC

Ken W7EKB

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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net
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