[AMRadio] RE: Line Voltage [was 6BE6]

Merz Donald S merz.ds at mellon.com
Thu Jun 24 14:45:19 EDT 2004

I don't think it is critical to reduce the line voltage. It's really just a preference. Over the years, I have used hamfest Variacs and EMI/RFI filters from Corcom and others, with fusing or circuit breakers, to build distribution boxes from which I feed my boatanchors and through which I can control the voltage they receive. I have kids with prying hands. So this second layer of power control also keeps the gear from being damaged when they come along and absent-mindedly flip an on/off switch 15 times out of sheer nervous, childhood energy. (In case you are wondering, the Variac controls can't be played with because they are set and then sealed inside the case of each of these boxes.)

It's a setup that serves me well on several levels. But it isn't right for everyone.
73, Don Merz, N3RHT

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of Jim Wilhite
Sent: Thursday, June 24, 2004 2:30 PM
To: Discussion of AM Radio
Subject: Re: [AMRadio] 6BE6

----- Original Message ----- 
From: "David Knepper" <cra at floodcity.net>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Thursday, June 24, 2004 9:53 AM
Subject: Re: [AMRadio] 6BE6

> Interesting experiment is put a variac on your receiver to see how low you
> can go without affecting performance.  I have found that I can go to 100
> on my Collins without any serious degradation of performance.
> Just my two cents worth.
> Dave, W3ST
> Publisher of the Collins Journal
> Secretary to the Collins Radio Association
> www.collinsra.com

I have, also, run the equipment with a variac, but at the risk of opening a
long discussion, I researched operating AC voltages of most equipment I own.

What I have found is that even the old equipment is designed for operation
at 115-117 VAC input.  Now the power company uses a 10% tolerance which
means the upper voltage can be up to 130-132 volts and the lower is, of
course, 100-104 volts.  Below 100 volts is considered a brown out, above is
considered a spike.

Considering the equipment manuals specs, that is within tolerance.    So if
that is a fact, the equipment should not suffer from voltages above 125
volts.  I have an RCA power line monitor that I calibrated at line voltage
at a previous location that I just plugged in a couple of days ago.  At its
peak, the AC line voltage was 130 and the low was 126.  At the previous
location the voltage ran about 121 volts.

I called the power company and talked to the head lineman who told me on
rural drops they run the voltage at 127 peak.  I told him of my findings and
he sent the lineman out who measured the terminal voltage at the meter.  I
now see 127 volts on the monitor at peak and about 123 volts at low.

He explained they have steppers on the transformers and they could be set to
different voltages and if the measured voltage was above 127 they would
reduce it, and they did what he said.  I asked him to step it to about
124-125 but the guy evidently didn't want to do that.

Now if I can just believe the equipment manuals I should be in better shape.
I sure hope they aren't wrong like the 6BE6 manufacturers.

73  Jim
de W5JO

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