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    Variac's on sale right now at Circuit Specialists in AZ

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    bluemeanies

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by bluemeanies on Mon Jul 31, 2017 8:34 am

    Tubes4ever wrote:Speaking of Kill O Watts, I noticed that mine shows the voltage as almost 2 volts below what I measure with both of my Fluke Meters.  I was wondering what others who own a Kill O Watt have observed as far as voltage accuracy?  I realize that 2 volts isn't that big of a deal, but with a display that shows tenths of a volt, I would expect better accuracy.


    Pretty much my Fluke is right on the money comparing it the kill-O-watt. However, it does vary from day to day being off 1-2 volts as mentioned.
    Nothing is perfect and we have no control as to what the electric companies are serving us in voltage especially in my area having an International Airport and Boeing within a couple of miles from where I live.
    Having the Variac I feel I do have some control especially when I am registering 125volts coming into my system.
    The Stacco is a contender.
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    deepee99

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by deepee99 on Mon Jul 31, 2017 1:51 pm

    Just FWIW, the "nominal" voltage in the U.S. and Canada is 120VAC delivered to your meter, but federal standards permit a slop factor of 10 percent, i.e. 114VAC to 126 VAC is considered within the 120VAC 60-cycle federal standard. That's a pretty wide swing for sensitive audio gear. Solid-state equipment dislikes the low side, tube equipment suffers at the high side.
    Resistance commencing at your breaker panel and continuing through the house wiring will probably drop the actual voltage to the outlet a tad, depending on the length of Romex from the panel to the plug, quality of connexions, and the other loads on that particular breaker.
    One way to deal with voltage variations and noise is to run a dedicated circuit directly from the breaker panel to the outlet you plug your stereo and its peripherals in to. A 20-amp breaker at the panel end is more than adequate; less than that and a good-quality voltage conditioner will trip it once in awhile, which is a pain. Also, a hospital-grade outlet when you've run that dedicated line is a good idea. Forget those $10,000 power cables everyone is hawking. Dedicated circuit>GFCI>sine-wave power regulator and you're safe as houses.
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    Tubes4ever

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by Tubes4ever on Mon Jul 31, 2017 7:38 pm

    bluemeanies wrote:
    Tubes4ever wrote:Speaking of Kill O Watts, I noticed that mine shows the voltage as almost 2 volts below what I measure with both of my Fluke Meters.  I was wondering what others who own a Kill O Watt have observed as far as voltage accuracy?  I realize that 2 volts isn't that big of a deal, but with a display that shows tenths of a volt, I would expect better accuracy.


    Pretty much my Fluke is right on the money comparing it the kill-O-watt. However, it does vary from day to day being off 1-2 volts as mentioned.
    Nothing is perfect and we have no control as to what the electric companies are serving us in voltage especially in my area having an International Airport and Boeing within a couple of miles from where I live.
    Having the Variac I feel I do have some control especially when I am registering 125volts coming into my system.
    The Stacco is a contender.

    Yeah, I have the variation from day to day as well. I meant that my Kill O Watt reads almost 2 volts below the Fluke simultaneously.
    I opened the Kill O Watt hoping that there was a calibration adjustment, there isn't any.
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    deepee99

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by deepee99 on Mon Jul 31, 2017 8:16 pm

    Tubes4ever wrote:
    bluemeanies wrote:
    Tubes4ever wrote:Speaking of Kill O Watts, I noticed that mine shows the voltage as almost 2 volts below what I measure with both of my Fluke Meters.  I was wondering what others who own a Kill O Watt have observed as far as voltage accuracy?  I realize that 2 volts isn't that big of a deal, but with a display that shows tenths of a volt, I would expect better accuracy.


    Pretty much my Fluke is right on the money comparing it the kill-O-watt. However, it does vary from day to day being off 1-2 volts as mentioned.
    Nothing is perfect and we have no control as to what the electric companies are serving us in voltage especially in my area having an International Airport and Boeing within a couple of miles from where I live.
    Having the Variac I feel I do have some control especially when I am registering 125volts coming into my system.
    The Stacco is a contender.

    Yeah, I have the variation from day to day as well. I meant that my Kill O Watt reads almost 2 volts below the Fluke simultaneously.
    I opened the Kill O Watt hoping that there was a calibration adjustment, there isn't any.
    Go with God, Grasshopper, Trust your Fluke.
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    Tubes4ever

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by Tubes4ever on Tue Aug 01, 2017 1:40 am

    deepee,

    I do trust my Fluke. I know the Kill O watt is wrong. Just wondering if this is the norm?
    Just seems with modern electronics that it should be very easy to reliably produce a voltmeter in the Kill O Watt with greater than .5 volt accuracy at 120 vac in a mass produced product.

    wildiowa

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by wildiowa on Tue Aug 01, 2017 10:49 am

    I am a simple farm boy and this is what I think on this deal. As you recall my voltage here is sometimes 126 VAC. Get a Chinese Variac, appreciate the price and know that it is not a $200 or $300 unit. Assume the meter is wrong, but the functionality is there. Use your VOM to set up your voltage, check the polarity if you want, plug it in and enjoy and forget about it. Yes, it will vary slightly depending on your incoming voltage, but a volt here or there is no biggie when compared to the larger issue of knocking it down from like 126. I personally prefer the clunky Variac for tube amps. Some things are clunky, mechanical but still are the best...like a Hammond B3 and a Leslie.
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    j beede

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by j beede on Tue Aug 01, 2017 1:31 pm

    My mains supply typically runs between 118V and 122V. My power company agreed to move my service onto a lower "tap" at the local step-down transformer--for a fee (of course). That drops my supply range to about 113V to 117V. I am happy with that. I'm not certain that the modern "energy star" appliances in our home will appreciate that unexpected drop in mains supply.

    Actually I made up the part about the power company lowering my supply level Smile. What I really did was to add a little bucking transformer to drop the output of a power strip by about five volts. Nice sine wave in, slightly smaller but equally nice sine wave out... just for my ca. 1960 tube gear. The appliances hum along with the full voltage all day and night.

    For my MkIIIs I built under-chassis cap boards using series/balanced pairs of 450V electrolytics to provide copious DCWV margin. I left the quad caps in place (disconnected) to retain the stock look. My MkVI (that's VI not IV) and W-5M were designed using this series cap approach in the HT supplies by Dynaco and Heathkit. The MkIII should have been done this way from the get go--but Messrs. Hafler and Laurent were limited by their sub-$100 MSRP target I suppose.

    I bias my amps a little on the light side with the supply at the higher end its range and let it wander from there. Like many others I run my 6550/KT-88 outputs with a bit less bias than the datasheet allows.

    ...j
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    deepee99

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by deepee99 on Tue Aug 01, 2017 2:56 pm

    I'm just thinking I'll run a drop-cord to Grand Coulee dam. Got enough cable for that Smile
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    Kentley

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by Kentley on Tue Aug 01, 2017 8:46 pm

    Re: U.S. AC Power acceptable variation.
    There seems to be widespread dissension about the actual allowable variation in the line voltage. Some say +/- 5%, which would give 114-126. Others claim the actual regs specify +/- 10%, which would yield 108-132. It seems logical to assume (!!!) that the latter set of ranges is the one adhered to. Right now, my line AC is an all-time low of 113VAC. I doubt that bringing this to the attention of National Grid would elicit any response other than a quiet yawn.
    This situation (low line voltage) has led me to a workable solution, possible only because my ST-120 was built with the time-delay relay. The Weber WS-1 SS rectifier is designed with no sag resistors. So my B+ voltage as measured on the driver board is pretty close to the center of acceptable range -- 386 VDC -- the range is 370 - 410. And the bias pots are generally around 10 o'clock.
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    Peter W.

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by Peter W. on Wed Aug 02, 2017 8:03 am

    https://www.cdw.com/shop/products/Tripp-Lite-1000VA-800W-Line-Interactive-UPS-Sine-Wave-120V-Rackmount-2U-TAA/1923328.aspx?cm_cat=GoogleBase&cm_ite=1923328&cm_pla=NA-NA-TRI_BA&cm_ven=acquirgy&ef_id=WUgmggAAAKtl5okB:20170802113356:s&gclid=CjwKCAjw8IXMBRB8EiwAg9fgMBoz0yS-m4ApcExYGxNmXe24JTqUyNy1SkFLHpnitwuGwWn68dVXXBoC1skQAvD_BwE&s_kwcid=AL!4223!3!47988697099!!!g!64450928333!    

    Does not seem overly complicated nor particularly expensive to me for the basics - if one's power is as bad as described.

    National Standards:   https://www.pge.com/includes/docs/pdfs/mybusiness/customerservice/energystatus/powerquality/voltage_tolerance.pdf  A little bit dense to read, but the potential for variation is considerable.

    Those of you at some distance from the source, in areas where there has been considerable growth, you are at particular risk, as suppliers have raised the voltage in the distribution lines so that existing conductors can carry additional capacity. Meaning that you may be running at the limit of the local step-down transformers.

    I will state, again, for the record, that variable  autotransformers, while better than nothing, are not designed to create a steady-state output, but to drop (or raise) input voltage at some proportion to the setting of the transformer. They also can be a source of noise, and if run constantly at anything approaching their load rating will get hot. Note that the largest risk of an VAT is the wiper - a small graphite button (if quality devices, otherwise a simple copper/bronze leaf-spring) that carries the entire load. Hence the need for significant over-sizing if used as a constant control.

    We are blessed with "good" power - inasmuch as we are in a very old neighborhood with almost no additional development since 1900 - so the increase in load has been relative to additional consumers - central AC, appliances and so forth, not 300 new houses on the same distribution line. But if I were in an area with such wild fluctuations as described here, I would go with a decent line-conditioner. Were I to be into belts, suspenders and Velcro, I would feed such a conditioner through a heavy-duty VAT at say.... 118 V or so as a midpoint.  And let the LC handle the rest. We get about 118 V as our steady-state at the wallplate here. Even mid-summer when the AC load is at its highest.

    You pays you money, you makes you choice. What is appropriate for my location is unlikely to be entirely appropriate to yours.

    On Kill-A-Watt meters - they are about as precise as a diesel engine, and that is no big deal when one considers their basic purpose, which is a snapshot of actual consumption at any given location at any given time *relative* to a previous future or time. Does anyone here remember the term "speedometer error"? This was the amount of slop expected in the typical automotive speedometer that the "Cops" would typically permit a drive before pulling one over for speeding. In Pennsylvania, for one example, the 'courtesy' was about 15% of actual speed. A study was done in about 1968/9 or so, and it was determined that at a cost of about $0.02 per car, this error could be eliminated, or reduced to a variation based on tire wear (really). Two things happened: The automobile industry howled that this cost would be excessive across total production (about 9,000,000 units in the US alone - $180,000. Really?), and the AAA howled that this would cause all sorts of unjust arrests for speeding. Never happened. Look at the Kill-A-Watt meter as a similar device. It is only as accurate as it must be. A Fluke Meter is designed to be accurate - and costs accordingly.


    Last edited by Peter W. on Wed Aug 02, 2017 10:23 am; edited 1 time in total (Reason for editing : Punctuation.)

    tk125

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by tk125 on Wed Aug 02, 2017 4:27 pm

    deepee99 wrote:
    slate1 wrote:
    Peter W. wrote:
    deepee99 wrote:  >>SNIPPAGE<<
    Bite the bullet, get a studio-grade Furman. They have some solid-state internals but basically are just a great big multi-tapped autoformer and your gear will see a pure sine wave, clamped at 121 VAC regardless of line voltage. Plug it into a manual-reset GFCI and run all your gear off of it. Cheapest insurance on the planet.

    Yep.

    Just to be clear - the Furman units, like the P1800 regulate to approximately 120v +/-5v as long as the input voltage is between 100-140v.  The APC H15 Conditioner (which I own and has been very reliable) provides close to the same level of regulation (120v +/- 5% between 102-132v) at a fraction of the cost.  Neither of the devices, however, will keep me consistently under the 123v I'm trying to achieve with the APC providing potentially up to 127v.

    I understand and appreciate the lack of surge protection, but in the end though, the variac seems like it would be a better choice for accurate voltage regulation, although requiring more "maintenance" - I'm wondering if I shouldn't just plug a kill-a-watt P4400 meter into the variac to get a better quality reading than the analog sweep meter?  (you'll have to google it - won't let me post a link because I haven't been a member for 7 days)

    Simply set the variac to 117v before powering up the amp and I believe  I'm set.  Also wondering if I should just plug the variac into the APC H15, providing surge protection, or just straight into the wall which, granted, would leave me exposed to spikes.

    The cheaper Furmans, like the 1800 models, do indeed have a 5-volt slop factor, which is still pretty good. I use an 1800 in the den to protect a combination of tube pre-amp and s/s amp.  Furman's studio grades, such as the SPR-20i I use in my all-tube main system have a 1-volt variation (off 121) within the input voltage range you mentioned. Believe me, I spent hours with their English-as-first-language-speaking tekkies before dropping 2 large on it. All I can say again, the sumbitch does its job.
    If you're going to drop $30 on a kill-a-watt, why not add another $70 and get a Fluke, which will give you far greater accuracy and utility. And again, you can "set" your Variac to 117 VAC (based on 120 VAC line voltage at the time) if your line voltage has a momentary spike to 130, the Variac will be right behind it at 127 VAC.
    And to preach to the choir, if you don't have a manual-reset GFCI plugged into your wall outlet, nothing will save you from spikes, up or down.
    BTW, Welcome to the board. I'm one of the noisier ones here, so take whatever I say with a grain of salt.

    I also use the Furman SPR-20i. I plugged it into my Variac and ran the input from 113V to 126V, and it controlled the output voltages over that range between 118.5V and 121V. I did discover that it responds a little faster when the input voltage increases vs when it is decreasing. Don't know why and neither did Furman. I also asked them why I got readings of 118.5V when it is supposed to output 120+/-1V. They said they thought the unit was working fine. What it is doing is switching taps on a big toroidal autoformer using SCR switches (for slient switching), which is also why you get good RMS output. I'm not hung up about the 0.5V discrepancy since it's a lot better than watching my line voltage go down to 115v on a big air conditioning day here in the south, vs 123V at night. Mine keeps the line at 118.5 to 120, and my tubes are happy!

    RE: the Kill-a-Watt accuracy. I measured the Variac output and the Furman output with a Keithley 2015 DMM and compared it to the Kill-A-Watt. The KAW is generally about 0.7 to 0.8V low all the time. I compared my Keithley to a couple other hand held DMM's I have, and they compared within 0.1V in general on the 120V scale. I use my Keithley as my standard.
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    deepee99

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by deepee99 on Wed Aug 02, 2017 5:26 pm

    tk125 wrote:
    deepee99 wrote:
    slate1 wrote:
    Peter W. wrote:
    deepee99 wrote:  >>SNIPPAGE<<
    Bite the bullet, get a studio-grade Furman. They have some solid-state internals but basically are just a great big multi-tapped autoformer and your gear will see a pure sine wave, clamped at 121 VAC regardless of line voltage. Plug it into a manual-reset GFCI and run all your gear off of it. Cheapest insurance on the planet.

    Yep.

    Just to be clear - the Furman units, like the P1800 regulate to approximately 120v +/-5v as long as the input voltage is between 100-140v.  The APC H15 Conditioner (which I own and has been very reliable) provides close to the same level of regulation (120v +/- 5% between 102-132v) at a fraction of the cost.  Neither of the devices, however, will keep me consistently under the 123v I'm trying to achieve with the APC providing potentially up to 127v.

    I understand and appreciate the lack of surge protection, but in the end though, the variac seems like it would be a better choice for accurate voltage regulation, although requiring more "maintenance" - I'm wondering if I shouldn't just plug a kill-a-watt P4400 meter into the variac to get a better quality reading than the analog sweep meter?  (you'll have to google it - won't let me post a link because I haven't been a member for 7 days)

    Simply set the variac to 117v before powering up the amp and I believe  I'm set.  Also wondering if I should just plug the variac into the APC H15, providing surge protection, or just straight into the wall which, granted, would leave me exposed to spikes.

    The cheaper Furmans, like the 1800 models, do indeed have a 5-volt slop factor, which is still pretty good. I use an 1800 in the den to protect a combination of tube pre-amp and s/s amp.  Furman's studio grades, such as the SPR-20i I use in my all-tube main system have a 1-volt variation (off 121) within the input voltage range you mentioned. Believe me, I spent hours with their English-as-first-language-speaking tekkies before dropping 2 large on it. All I can say again, the sumbitch does its job.
    If you're going to drop $30 on a kill-a-watt, why not add another $70 and get a Fluke, which will give you far greater accuracy and utility. And again, you can "set" your Variac to 117 VAC (based on 120 VAC line voltage at the time) if your line voltage has a momentary spike to 130, the Variac will be right behind it at 127 VAC.
    And to preach to the choir, if you don't have a manual-reset GFCI plugged into your wall outlet, nothing will save you from spikes, up or down.
    BTW, Welcome to the board. I'm one of the noisier ones here, so take whatever I say with a grain of salt.

    I also use the Furman SPR-20i.  I plugged it into my Variac and ran the input from 113V to 126V, and it controlled the output voltages over that range between 118.5V and 121V.  I did discover that it responds a little faster when the input voltage increases vs when it is decreasing.  Don't know why and neither did Furman.  I also asked them why I got readings of 118.5V when it is supposed to output 120+/-1V.  They said they thought the unit was working fine.  What it is doing is switching taps on a big toroidal autoformer using SCR switches (for slient switching), which is also why you get good RMS output.  I'm not hung up about the 0.5V discrepancy since it's a lot better than watching my line voltage go down to 115v on a big air conditioning day here in the south, vs 123V at night.  Mine keeps the line at 118.5 to 120, and my tubes are happy!

    RE:  the Kill-a-Watt accuracy.  I measured the Variac output and the Furman output with a Keithley 2015 DMM and compared it to the Kill-A-Watt.  The KAW is generally about 0.7 to 0.8V low all the time.  I compared my Keithley to a couple other hand held DMM's I have, and they compared within 0.1V in general on the 120V scale.  I use my Keithley as my standard.
    For reasons known only to Furman, the voltage reading on the meter is what it's seeing coming from the wall. Set the meter to amperage and that will indicate what it's putting out. That's why I just leave the toggle on the amps reading. The amperage gauge tells you what the total load actually is, regardless of input voltage. If that starts to wobble a bit, you've probably got a tube or component about to go pear-shaped.
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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Thu Aug 31, 2017 12:07 pm

    FYI - Ordered this panel meter to replace the analog one in my variac:

    http://www.mpja.com/Panel-Meter-Snap-in-3-Digit-300VAC-Red/productinfo/30220+ME

    Will post results once I get it (or maybe, "if" ha ha) installed in this:

    https://www.circuitspecialists.com/variac-variable-ac-ps05kva.html

    I was going to try and do the retrofit described on Circuit Specialists site, but this seemed like a much easier route.
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    Peter W.

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by Peter W. on Thu Aug 31, 2017 12:14 pm

    slate1 wrote:FYI - Ordered this panel meter to replace the analog one in my variac:

    http://www.mpja.com/Panel-Meter-Snap-in-3-Digit-300VAC-Red/productinfo/30220+ME

    Will post results once I get it (or maybe, "if" ha ha) installed in this:

    https://www.circuitspecialists.com/variac-variable-ac-ps05kva.html

    I was going to try and do the retrofit described on Circuit Specialists site, but this seemed like a much easier route.

    Note: Variacs are not compatible with most GFI (Ground Fault Interrupter) wall outlets.  We have found that the inductive load that the Variac represents is not compatible with most GFI circuits and they will trip the breaker.

    This line in the description makes it absolutely imperative that this device be used with an isolation transformer!
    Note that I have a Heath IP5220 Iso-Variac that is entirely happy with running from a GFCI outlet. I expect it is the isolation that allows that to happen, not the 'superiority' of a General Radio Variac vs. a Chinese auto-transformer. But, if a device will trip a GFCI device, it is capable of 'tripping' the user as well.  Just something to keep in mind.
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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Thu Aug 31, 2017 12:34 pm

    Peter W. wrote:
    slate1 wrote:FYI - Ordered this panel meter to replace the analog one in my variac:

    http://www.mpja.com/Panel-Meter-Snap-in-3-Digit-300VAC-Red/productinfo/30220+ME

    Will post results once I get it (or maybe, "if" ha ha) installed in this:

    https://www.circuitspecialists.com/variac-variable-ac-ps05kva.html

    I was going to try and do the retrofit described on Circuit Specialists site, but this seemed like a much easier route.

    Note: Variacs are not compatible with most GFI (Ground Fault Interrupter) wall outlets.  We have found that the inductive load that the Variac represents is not compatible with most GFI circuits and they will trip the breaker.

    This line in the description makes it absolutely imperative that this device be used with an isolation transformer!
    Note that I have a Heath IP5220 Iso-Variac that is entirely happy with running from a GFCI outlet. I expect it is the isolation that allows that to happen, not the 'superiority' of a General Radio Variac vs. a Chinese auto-transformer. But, if a device will trip a GFCI device, it is capable of 'tripping' the user as well.  Just something to keep in mind.

    Thanks Peter! Yes, I have it plugged into a manual reset GFCI and it has yet to trip it, thankfully!
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    deepee99

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by deepee99 on Thu Aug 31, 2017 1:27 pm

    slate1 wrote:
    Peter W. wrote:
    slate1 wrote:FYI - Ordered this panel meter to replace the analog one in my variac:

    http://www.mpja.com/Panel-Meter-Snap-in-3-Digit-300VAC-Red/productinfo/30220+ME

    Will post results once I get it (or maybe, "if" ha ha) installed in this:

    https://www.circuitspecialists.com/variac-variable-ac-ps05kva.html

    I was going to try and do the retrofit described on Circuit Specialists site, but this seemed like a much easier route.

    Note: Variacs are not compatible with most GFI (Ground Fault Interrupter) wall outlets.  We have found that the inductive load that the Variac represents is not compatible with most GFI circuits and they will trip the breaker.

    This line in the description makes it absolutely imperative that this device be used with an isolation transformer!
    Note that I have a Heath IP5220 Iso-Variac that is entirely happy with running from a GFCI outlet. I expect it is the isolation that allows that to happen, not the 'superiority' of a General Radio Variac vs. a Chinese auto-transformer. But, if a device will trip a GFCI device, it is capable of 'tripping' the user as well.  Just something to keep in mind.

    Thanks Peter!  Yes, I have it plugged into a manual reset GFCI and it has yet to trip it, thankfully!
    Either you're lucky, or you're next.
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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Thu Aug 31, 2017 1:37 pm

    deepee99 wrote:
    slate1 wrote:
    Peter W. wrote:
    slate1 wrote:FYI - Ordered this panel meter to replace the analog one in my variac:

    http://www.mpja.com/Panel-Meter-Snap-in-3-Digit-300VAC-Red/productinfo/30220+ME

    Will post results once I get it (or maybe, "if" ha ha) installed in this:

    https://www.circuitspecialists.com/variac-variable-ac-ps05kva.html

    I was going to try and do the retrofit described on Circuit Specialists site, but this seemed like a much easier route.

    Note: Variacs are not compatible with most GFI (Ground Fault Interrupter) wall outlets.  We have found that the inductive load that the Variac represents is not compatible with most GFI circuits and they will trip the breaker.

    This line in the description makes it absolutely imperative that this device be used with an isolation transformer!
    Note that I have a Heath IP5220 Iso-Variac that is entirely happy with running from a GFCI outlet. I expect it is the isolation that allows that to happen, not the 'superiority' of a General Radio Variac vs. a Chinese auto-transformer. But, if a device will trip a GFCI device, it is capable of 'tripping' the user as well.  Just something to keep in mind.

    Thanks Peter!  Yes, I have it plugged into a manual reset GFCI and it has yet to trip it, thankfully!
    Either you're lucky, or you're next.

    Not sure I understand?  I'm open to other suggestions for stepping down my variable line voltage (which swings from 120-125 or so) to either a constant 120 or my preferred 117 if anyone has any.  I have the ST-120 plugged into the variac, the variac plugged into a Shockshield Portable GFCI Plug with Surge Protection plugged into a PS Audio Ultimate Outlet.  Not sure I see what the problem is?  Please advise though if there's something unsafe I should be aware of!  I am not an engineer by any stretch of the imagination! Laughing

    .....hmmmmmm, I do think I have a Tripp Lite isolation transformer somewhere that I used years ago with another amp.
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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Sat Sep 02, 2017 4:46 pm

    Took some finagling but got the meter installed and it works very well.  Had to remove the display from the bezel, cut the red film from the bezel, then remove the clip taps from the original bezel that was used with the analog meter.  

    Removed the analog meter, glued the film to the back of the opening of the variac housing where the analog meter had been, glued the display to the film, wired it up, then glued the bezel to the front of the housing.

    There's a pot on the back of the display to adjust it - according to my Fluke it was only 1V off and was easily adjusted.

    Happy with the result for $6 and 15 minutes of work. Very Happy

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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Thu Sep 07, 2017 7:13 pm

    Quick question. Should I be equally concerned about running the SP-13 preamp or PH-16 phono stage at voltages up to, say, 123v?  I have it plugged into an AVR that will keep it between around 117 and 123.
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    tubes4hifi
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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by tubes4hifi on Fri Sep 08, 2017 1:41 pm

    Cole, that's a perfectly good voltage range for the preamps
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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Fri Sep 08, 2017 1:45 pm

    tubes4hifi wrote:Cole, that's a perfectly good voltage range for the preamps

    Excellent! Thanks!
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    DavidR

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by DavidR on Wed Sep 13, 2017 7:44 pm

    slate1 wrote:Took some finagling but got the meter installed and it works very well.  Had to remove the display from the bezel, cut the red film from the bezel, then remove the clip taps from the original bezel that was used with the analog meter.  

    Removed the analog meter, glued the film to the back of the opening of the variac housing where the analog meter had been, glued the display to the film, wired it up, then glued the bezel to the front of the housing.

    There's a pot on the back of the display to adjust it - according to my Fluke it was only 1V off and was easily adjusted.

    Happy with the result for $6 and 15 minutes of work. Very Happy


    By chance did you check the accuracy of the digital voltage set point/output with a DMM? The 20A unit doesn't have that feature.
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    slate1

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    Re: Variac's on sale right now at Circuit Specialists in AZ

    Post by slate1 on Wed Sep 13, 2017 7:59 pm

    DavidR wrote:
    slate1 wrote:Took some finagling but got the meter installed and it works very well.  Had to remove the display from the bezel, cut the red film from the bezel, then remove the clip taps from the original bezel that was used with the analog meter.  

    Removed the analog meter, glued the film to the back of the opening of the variac housing where the analog meter had been, glued the display to the film, wired it up, then glued the bezel to the front of the housing.

    There's a pot on the back of the display to adjust it - according to my Fluke it was only 1V off and was easily adjusted.

    Happy with the result for $6 and 15 minutes of work. Very Happy


    By chance did you check the accuracy of the digital voltage set point/output with a DMM? The 20A unit doesn't have that feature.

    Are you referring to the voltage shown on the top dial or the voltage displayed on the digital display I added?

    If it's checking the accuracy of the digital display, then, yes - as I stated in the original post, I checked it with my fluke meter and adjusted the pot on the digital meter accordingly. It was only ~1v off out of the box and easily corrected. It's dead accurate now.

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    Re: Variac's on sale right now at Circuit Specialists in AZ

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