Re: [Drakelist] Variac

[Ed Tanton]

I'm with Evan, Neil. Be certain you do this in a quiet environment. The
instant you perform an increase and you hear a frying/crackling noise, BACK
DOWN 'til you don't, and give it an hour or two at 5V or 10V lower than
where the noise started. I actually had this non-destructively happen, and
the device (I forget what) ultimately survived.

 

Ed Tanton
 
website: http://www.n4xy.com   
 
All emails  &  checked by 
Norton AntiVirus with AutoProtect 

--
Wag more / Bark less
--

 

///snip

 

Neil, 

 

I'm somewhat compulsive about such things.  The older a rig is, or the
longer it has set idle, the longer the "program" or process.  In the worst
case, I use 10 volts per hour increase.  In other cases, I start with 10
volts per 15 minutes.  My Variac has three meters---one for voltage, one for
current, and one for power in watts.  It is easy to see that when the
ammeter increase at about the same amount as the voltage, you readily know
there is a problem and not to proceed until fault isolation has been
completed.

 

73,

 

Evan, K9SQG



///snip

___
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist

Re: [Drakelist] Variac

[K9sqg]

Neil,


I'm somewhat compulsive about such things.  The older a rig is, or the longer 
it has set idle, the longer the "program" or process.  In the worst case, I use 
10 volts per hour increase.  In other cases, I start with 10 volts per 15 
minutes.  My Variac has three meters---one for voltage, one for current, and 
one for power in watts.  It is easy to see that when the ammeter increase at 
about the same amount as the voltage, you readily know there is a problem and 
not to proceed until fault isolation has been completed.


73,


Evan, K9SQG



-Original Message-
From: Neil M Califano 
To: Drakelist 
Sent: Sat, Oct 15, 2011 10:25 am
Subject: [Drakelist] Variac


When bringing up a radio on a variac, do I slowly continuously turn the power 
up 
or go step by step? I've never used one. 

___
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist

 
___
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist

[Drakelist] Variac

[Neil M Califano]

When bringing up a radio on a variac, do I slowly continuously turn the power 
up or go step by step? I've never used one. 

___
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist

Re: [drakelist] Variac

[Ron Wagner]

Ron Wagner <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--
Had an advertisment just the other day from MCM electronics, they had one 
on sale for about $70, normally about $125.  mcminone.com

73,
Ron

Visit my astronomy home page.   http://www.dma.org/~wagner
Amateur Radio Station: WD8SBB - Ron  and  KB8NRP - Joann


On Sun, 26 Mar 2006, Bill wrote:



Bill <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--

To expand on the question of a variac.who sells such?  Where can one be 
bought...?


Bill VE3ES

--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in 
body

Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--


--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--

Re: [drakelist] VARIAC CAUTION

[af2c]

If my memory serves me correctlyA variac is a variable
"autotransformer."
Autotransformers have a single winding and, therefore, can not be used
for isolation purposes.
73,
Jay/AF2C

At 01:55 PM 3/26/06 -0500, you wrote:
One word of
caution. Some folks are under the impression that a variac also acts as
an isolation transformer. It is not and offers no isolation at all, so if
you are working with an AC/DC (transformerless) set, safety dictates the
use of an isolation transformer with or without the variac.
73,  
John,  W4AWM 
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date:
3/24/06



No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/06

[drakelist] VARIAC CAUTION

[W4AWM]

One word of caution. Some folks are under the impression that a variac also acts as an isolation transformer. It is not and offers no isolation at all, so if you are working with an AC/DC (transformerless) set, safety dictates the use of an isolation transformer with or without the variac.

73,  

John,  W4AWM

Re: [drakelist] Variac to revive tubes equipment

[Garey Barrell]

Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--
Frank -

This is just my opinion..

A Variac is essentially a variable transformer with a rotating slider to 
vary the AC line voltage from zero to as much as 20% OVER the input 
voltage.  It is NOT an isolation transformer.


A Variac is used primarily to test a unit (actually it's power supply) 
to determine if it will work over a range of line voltage.  In other 
words, turn the Variac down to lower the line voltage ten or fifteen 
percent and see if the tested unit's voltages stay within range, then 
turn the Variac up to increase the line voltage the same amount and 
again check the unit's voltages (and heat sink temperature for 
regulators) for proper operation.


Variacs are also useful to bring up the filament power on big 
transmitting tubes to minimize the shock of heavy current to a low 
"cold" resistance filament.


Generally speaking, it is NOT a good idea to bring a piece of 
equipment's line voltage up from zero, slowly or otherwise, since it can 
result in all sorts of strange behavior.  A good example was posted here 
just a few days ago where someone was bringing up a PS-7 power supply 
"slowly" and could not get it to work at all.  ALL "consumer" equipment 
is designed to have the line voltage applied instantly!


The best procedure I have found, and use, for "first time" use of an 
unknown piece of equipment is to put a standard 40 - 100W light bulb in 
series with the line voltage.  Then turn on the power.  The bulb should 
glow brightly for a second or so and then dim.  Depending upon the power 
drawn by the equipment being tested vs the light bulb chosen, the bulb 
should go very dim and the device will most likely operate at the 15 - 
20% low line voltage being applied through the bulb.  If this is the 
case, merely short out the bulb and proceed to check voltages and heat 
for any abnormal indications.


On the other hand, should the bulb glow brightly, and continue to do so, 
it indicates a shorted filter capacitor, defective rectifier, bad 
transformer, or ...   In this case, unplug the rectifier tube (if 
present) and see if the bulb dims.  If it does, then either the tube or 
filter capacitor(s) are defective, or some other fault such as a shorted 
power bus is present.  Ohmmeter checks (with power OFF!) should show the 
fault.   If the bulb stays bright with the rectifier tube out, then 
either the transformer is shorted, or some wiring or component fault in 
the primary circuit is present.  If the rectifiers are silicon diodes, 
then you would have to disconnect them to perform the above test.  In 
any event, even if there is a direct short somewhere in the device, 
nothing is damaged further, the light bulb just glows brighter!!


One additional step I use is to check the electrolytic filter capacitors 
before ever applying ANY power with an ESR meter.  In fact, for simple 
units such as a receiver or transmitter I check ALL electrolytics with 
the ESR meter before applying power.


I own several Variacs, and never use them to "bring equipment up 
slowly".   For initial testing of vintage (or other) equipment, I would 
suggest investing in a light bulb mounted on a board or box with a line 
cord and plug, an AC outlet and a toggle switch to short the bulb.  
Spend the money you saved over the Variac on an ESR meter and you'll 
have a much more useful test setup.


73, Garey - K4OAH
Atlanta

Drake B & C-Line Service CDs




francobevi francobevi wrote:


"francobevi francobevi" <[EMAIL PROTECTED]> made an utterance to 
the drakelist gang

--
I have some tube equipment to power up safely. I heard about someone 
use Variac. I do not have one and I would know what it is (a kind of 
transformer to gradually increase AC voltage?), what type to 
eventually buy and a procedure to use it correctly to revive old rigs.


Bests,
Frank


--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--

Re: [drakelist] Variac to revive tubes equipment

[Jim Shorney]

"Jim Shorney" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--
On Sun, 26 Mar 2006 14:34:51 +, francobevi francobevi wrote:

>I have some tube equipment to power up safely. I heard about someone use 
>Variac. I do not have one and I would know what it is (a kind of transformer 
>to gradually increase AC voltage?), what type to eventually buy and a 
>procedure to use it correctly to revive old rigs.


What a variac is:

http://www.elect-spec.com/variac_tutorial.htm

Where to buy one: eBay, surplus stores, junk shops, online electronics
sellers, etc. Be cautious when buying a used one. One that has been
overloaded can have burned windings and/or a burned carbon brush, rendering
it unsafe at best and useless at worst. I can vouch for Michael, N0XY. If you
buy from him, you'll get a good one.

-Jim


--
TR7/RV7, TR6/RV6, T4XC/R4C, L4B, NCL2000, SB104A, R390A, GT550A/RV550A - all 
vintage, all the time!


--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--

Fw: [drakelist] Variac to revive tubes equipment

[Greg.]

"Greg." <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--
Yes a variac is and adjustable AC transformer, for instance such as this one:
http://www.rfelektronik.se/temp/Dsc_2558.jpg
http://www.rfelektronik.se/temp/Dsc_2562.jpg
It might not be a beauty but it bascially cost me nothing, and provides 
filtered 0-300vac 0-10Amp with power-on softstart aswell.

I guess there would be alot old cheap variac's on Ebay for instance...
However for tube filaments you can also use DC if you have an adjustable
current source...

//Greg



"francobevi francobevi" <[EMAIL PROTECTED]> made an utterance to the drakelist 
gang
--
I have some tube equipment to power up safely. I heard about someone use 
Variac. I do not have one and I would know what it is (a kind of transformer 
to gradually increase AC voltage?), what type to eventually buy and a 
procedure to use it correctly to revive old rigs.


Bests,
Frank



--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--

Re: [drakelist] Variac

[Michael NØXY]

=?ISO-8859-1?Q?Michael_N=D8XY?= <[EMAIL PROTECTED]> made an utterance to the 
drakelist gang
--
I have a 25A 0-140VAC Staco variac that I have been thinking about 
selling. It is a bit of overkill for bringing up old tube radios, but is 
wonderful for Tesla coil use. anyone interested can email me. It is half 
the retail price.


As for smaller ones, they can be found in lots of places. Google variac, 
ebay search variac. Look at hamfests and ask your local buddies.


Michael
N0XY

Bill wrote:


Bill <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--

To expand on the question of a variac.who sells such?  Where can one 
be bought...?


Bill VE3ES

--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist 
in body

Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--



--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--

[drakelist] Variac

[Bill]

Bill <[EMAIL PROTECTED]> made an utterance to the drakelist gang
--

To expand on the question of a variac.who sells such?  Where can 
one be bought...?


Bill VE3ES

--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--

[drakelist] Variac to revive tubes equipment

[francobevi francobevi]

"francobevi francobevi" <[EMAIL PROTECTED]> made an utterance to the drakelist 
gang
--
I have some tube equipment to power up safely. I heard about someone use 
Variac. I do not have one and I would know what it is (a kind of transformer 
to gradually increase AC voltage?), what type to eventually buy and a 
procedure to use it correctly to revive old rigs.


Bests,
Frank

_
Personalizza MSN Messenger con sfondi e fotografie! 
http://www.ilovemessenger.msn.it/


--
Submissions:drakelist@www.zerobeat.net
Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost:[EMAIL PROTECTED] - help in body of message
Zerobeat Web Page:  www.zerobeat.net - sponsored by www.tlchost.net
--