[Hammarlund] : Tube shields and heat

[Glen Zook via Hammarlund]

The target voltage, from most, if not all, major electric companies these days, is 125 VAC +/- 2-volts.  Especially during the warmer months, with air conditioning load, the voltage is on the higher side.  TXU, now Energy Futures Holding, has been running this since, at least, the early 1970s.  TXU is the electric company for almost half the State of Texas.

I worked for TXU over 10-years as a telecommunications consultant and was also a member of the TXU speakers board.  The speakers board provided people to present all sorts of subjects at seminars, organization meetings, and other public functions.  Although I generally spoke on lightning protection and grounding, on every occasion there would be someone who asked why their light bulbs didn't last long.

The answer was that the light bulbs sold in grocery stores, most home improvement centers, and so forth, were rated at 120-VAC.  Unfortunately, the ambient line voltage was, around here, 127 VAC which caused the light bulbs to fail.  I always suggested that they look for bulbs rated at 130-volts.  Home improvement stores usually had them but also not easy to find.  Of course, specialty lighting stores always had 130-volt bulbs available.

When I happened to "run into" someone who was at the occasion when I had suggested using 130-volt bulbs, and actually started using those bulbs, they would thank me saying that the new bulbs were working great.

Of course, the stores selling 120-VAC bulbs were very happy with the reduced life of the bulbs because people had to purchase more when the bulbs burned out.  I suspect the same situation exists with the new "low energy" bulbs.  I haven't looked for 130-volt versions and I do know that all of the bulbs being sold are not rated for the higher voltage.  At least any that I see at home improvement centers, Walmart, grocery stores, etc.
 
Glen, K9STH 

Website:  http://k9sth.net


On Monday, September 29, 2014 1:04 PM, Richard Knoppow <1oldlens1 at ix.netcom.com> wrote:
 



----- Original Message ----- 
From: "Bob Camp" <kb8tq at n1k.org>
To: "Guido Santacana" <gsantacanav at gmail.com>
Cc: "Hammarlund QTH LIST" <hammarlund at mailman.qth.net>
Sent: Monday, September 29, 2014 4:14 AM
Subject: Re: [Hammarlund] : Tube shields and heat


Hi

Most of these radios were designed in an era of 105 to 110V 
AC line voltage. We still call it 110 today, even though it 
probably is 118 to 124V. For some parts power does indeed 
follow voltage squared. That can be good or bad depending on 
what you are up against. A simple autotransformer based on a 
12V filament transformer will fix the problem without a lot 
of crazy effort.

Bob

     "Standard" power voltage in the USA seems to have begun 
at around 110 volts and gone up slowly. Around 1940 it was 
115 or 117 volts, later it became 120 volts. I monitored 
line voltage here for a while during a recent heat wave. It 
varied from as low as 108 volts to as high as 124 volts 
depending on time of day (how many people had air 
conditioners going etc). During light load times it crawls 
up to around 122 to `124 volts.  This is probably partly 
house wiring but was measured on a circuit with low demand, 
I think the variation was mostly from LADWP.
     The reason for higher supply voltages is simply to make 
up for the expected loss in the transmission lines. Using 
larger wire and higher capacity transformers would allow 
lower supply voltages but is expensive.
    A simple bucking transformer can compensate for high 
line voltage but where there is a lot of variation, 
especially where voltage goes low at times, a regulator of 
some sort is in order. The simplest is a Sola type constant 
voltage transformer.  The have a set of vices all their own 
but do work quite well.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com 

______________________________________________________________
Hammarlund mailing list
Home: http://mailman.qth.net/mailman/listinfo/hammarlund
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Hammarlund at mailman.qth.net

List Administrator: Duane Fischer, W8DBF
** For Assistance: dfischer at usol.com **


This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html