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FL 2100B input voltage

PostPosted: Mon May 07, 2007 2:53 pm
by enduro81
Is there any performance advantage when using 220 volt instead of 120 volts to power a FL 2100B Amp?
Thanks in advance

Bob B (KG4VIN)

220 Vs 117VAC

PostPosted: Mon May 07, 2007 4:57 pm
by W4CLM
Hi Bob this is a very interesting topic you bring up.
You know I often felt there was a real advantage to running those amplifier on 220VAC, BUT after many years and considerable thought on this I'm starting to have some change of opinion to this.

Here's how we got there.
If you wire your amp as per the manual when going on a 220 VAC line current, the plate voltage will be run up slightly higher by several hundred volts as to what it is right now on 117 VAC.

Years ago the AC coming into our homes here in the USA was right at or near 220 VAC, However you will often find in today's world that this voltage is much higher and actually closer to US voltage is 240VAC.

As per the factory wiring diagram for the FL-2100 series amplifiers you will note the way to wire your amplifier is to put both 110 VAC primary windings in series thus 110 + 110 = 220VAc. Makes sense to me.

Once this is done you will see your plate voltage on the amplifier jump from what before was typically 2,400 VDC on the amplifier up to that of something like 2600 VAC. This may not sound like a big difference. But I'LL just about guaranty you if your amp is wired for 117VAC right now and the capacitors are in good condition you'll likely have about 2400 on your plate voltage.

OK back to putting the FL-2100 on 220VAC. As previously noted , I suggest you measure your line voltage (Carefully) you will should note your 220 line will likely be closer to 240. THUS IN REALITY HERE IN THE USA INSTED OF WIRING THE TWO 110 VAC PRIMARIES IN SERIES, WE SHOULD REALLY BE WIRING THE TWO 117 VAC PRIMARIES IN SERIES.
117 VAC + 117 VAC = 234 VAC
THIS IS NOW MUCH CLOSER TO OUR 240 VAC coming into our homes that we typically have here in the USA.

In turn if this were to be done as suggested above. Your Plate voltage would truly remain as it was before at 2,400 volts DC on your 572B amplifier tubes and there really should be NO increase in plate voltage when going from 117 to 220 volt conversion on your primary.

Is it better to use the two 110 VAC windings the wire your amp 220 VAC as per the manual? Well I guess the jury is still out on this even after all these years. If you do this you will surely see the increase in the plate voltage from that of 2400 VDC up to that of 2600 VDC on your plates of the amplifier tubes.

Typically under NO load at 2400 VDC, your amp will drop down to 2,200 VDC under a typical (SSB) load when using the 117 VAC ac on the primary.

Having the amp wired (110 + 110 on the primary)
under NO load you will have about 2,600 VDC, your amp will drop down to 2,400 VDC under a typical load when wired for 220 VAC as per the manual.

In essence if the amp is truly wired correctly we should not really see any increase in plate voltage going from 117 then going to 220 on the primary.
A very close friend of mine who has successfully built MANY amplifiers enlightened me to this. At first I kept thinking he was full of bull and it really didn't matter, but I'LL tell you as much as I hate to admit it and I hate to be wrong. My good friend Sidney Lanier KG4NVZ has built many an amp and I have built none. I think he really has a valid point here.

So beating this dead horse just a little more.
Look at the tubes specifications for the Sylvetlana 572B

You will note that typical operation for (ICAS) Intermittent Continuous Amateur Service recommends 2400 VDC on the plates of the 572B tube.
With the maximum (ICAS) for class "B" operation being 2,750 VDC on the plates. A little more research on the world wide web and you'll likely find that Ameritron is running their AL-572 with even higher voltage, but likely biased down to make the tubes run cooler when in rest.

Bottom line, as I noted above I think the jury will remain out on this.
You may likely find as many opinions on this as people have noses and there are a lot of noses in the world. However when you consider the high points that my good friend Sidney points out in regards to the 220 VAC line in most American households today being higher then it was years ago, and compare that to the so called 220 VAC standard used elsewhere in the world, HE MAKES A GOOD POINT. And lastly considering that the parts for the FL-2100 amplifier series, doorknob capacitors, plate and loading variable condensers, plate RFC chokes and just good old simple 22 Ohm ~ 2 watt resistors that use to be plentiful and easy to find (they are used in the original design for parasitic chokes) the prices for all of these items has gone through the roof and will continue to climb almost every passing day, not to mention just finding the parts alone is getting harder from one year to the next. I've giving this a lot more thought in recent years, due to the cost of parts and availability.

So if you put the FL-2100 on 220VAC consider what we have said above. I have on my desk an FL-2100B currently wired for 220VAC, it is turned on and looking at it as we speak. It is showing 2,600 VDC on the plate voltage meter. The other FL-2100 amps I own are still on 117VAC. Even though we have gained a slightly higher plate voltage going from 2,400 to 2,600 volts DC on the plate. Any and all increase in plate voltage will produce wear and tear on the amplifier in the long run, along with the slightly higher increase of input / output power that I've managed to achieved by doing this. We need to keep in mind that we don't get anyting for free these days, so any increase in power may come with a price should the amplifier start to break down or the parasitic chokes crack or change value they may eventually fail to do their job causing more problems and expensive repairs. Thus more voltage in the amp, more current (More simply put I X E= Input power) the more power input to the tubes will likely result in more heat.
More heat & who knows? You decide.

Carol W4CLM

PostPosted: Tue May 08, 2007 3:50 am
by enduro81
Hi Carol

Thank you for the fast responce and the help that you keep giving
to everyone.

Bob B. (KG4VIN)

OK Bob

PostPosted: Tue May 08, 2007 3:23 pm
by W4CLM
OK BOb, I revised some of the spelling errors and tried to make that read with a little more contunity. By the way Sidney is signed on to this fourm. If I can only get him to speak up some, he may have something better to add on to this thread.

Carol W4CLM

This from Walter n9WB, makes a good point

PostPosted: Tue May 08, 2007 3:35 pm
by W4CLM
This from Walter N9WB form one of our many Yahoo Groups forums
in this case this forum is specifically for amplifiers.


You make an excellent point here Walt!
Yes indeed, in fact my buddy Sidney and I have discussed that side of the coin as well. You're right, in considering lead length from one's home breaker panel, how many things may be on that circuit and current, this all becomes a factor. Maybe the answer then is to wire the two 117VAC primaries in series and that would put the current matter to rest yet still allow one to use the typical 220++ actually about 240 we have here in the USA.

I'LL post this to the public fourm Walt.

--- In, "n9wb" <n9wb@...> wrote:
> Hello Carol:
> I both agree and disagree.
> I very much agree that placing the amplifier on 240 volts while set for 220 to soup it up is not a good idea. In terms of dB the increase in output is less than can be ever noticed on the air but is very hard on the amp. This can result in damaged bandswitches, filament overvoltage, and self oscillation.
> But the other issue is regulation and linearity.
> I agree that if you have good wiring in your house and good neutrals in your area, 120 volts may be as good as using 240 V. But how often is this the case? If one does use 120 V, the amp should always be plugged directly into the wall outlet. Power strips and multi taps must be avoided. A top quality outlet such as a Hubbell brand is necessary for a good high current connection. Most outlets used in homes sell for 87 cents. What else in the house in on that circuit. The freezer or the refrigerator ?
> One way to check the voltage at your outlet is to plug a 1200 to 1500 watt heater into it while measuring the voltage with a volt meter. If the voltage drops when the heater is energized, either shure up the 120 V circuit or put in a nice clean 240 V system. Keep in mind that if the rig is connected to the same outlet as the amp, it will be bouncing along with the amp. This can result in frequency shift on modulation peaks, "Donald Duck effect".
> A device such as an amplifier will draw 1/2 the current at 240 V as it will at 120 V for the same input power so the ohms law drop on a given size wire will be half.
> So in summary, the 120 volt circuit will have to be real beefy and solid to work as well as a 240 volt circuit with a high current device. Always set the transformer taps for the actual voltage being used, 237 instead of 220 in USA and do not tap the primary of a transformer below the mains voltage to increase output.
> Vy 73, Walt N9WB

I think Walter figured this one out for us

PostPosted: Tue May 08, 2007 3:43 pm
by W4CLM
On page 12 of the manual there is a picture of the transformer terminal
strip. On the left side are the line cord wires and two jumpers.

For 117 volt operation, one jumper connects the two 0 terminals together and
another connects the two 117 terminals together. This places the two 117
volt windings in parallel and in phase. One side of the line cord connects
to the 0 terminals and the other connects to the 117 terminals. This way
both windings are getting fed 117 in parallel and in phase.

For 237 volt operation, the two windings must be fed in series and in phase.
To do this remove both jumpers. Only one jumper will be used.

In the center there is a 0 and a 117 volt terminal adjacent to each other.
Use one jumper to connect these two together. The other jumper is not used.
One side of the power cord goes to the 0 terminal at the very bottom. The
other side of the power cord goes to the 117 terminal at the very top of the
terminal strip.

From bottom to top, one line cord wire to 0.
Jumper from center 117 to center 0
Second line cord wire to 117 on the top.

One jumper will remain unused. I usually tape this inside the amplifier in
case it needs to be changed back at some future time.

Vy 73, Walt N9WB

The proper wiring for so called 220 in the USA.

PostPosted: Tue May 08, 2007 4:51 pm
by W4CLM
OK Wlater done!
It's child's play to move it over. My DC voltage now dropped back to 2400 volts. (Note the links below for wiring pictures)

To bring this thread a little more into view. I measured my so called 220VAC line into my home and I have more like 250 VAC! That's a lot when you take into consideration the Peak to Peak voltage and so forth, it's likely pushing the amp pretty hard when it's wired using the two 110 AC primaries in series here in the USA. Likely outside the USA , in Europe and elsewhere the use of 220 VAC really means 220 VAC and surely it's kept much closer to specifications.

Years ago we use to call it 110 VAC here in the USA, but it's my understanding the voltage was pushed slightly higher to make up for such things as excessive line loss getting the current all the way to ones home!
Someone might clarify that better for me.

Anyway: Just to clarify your wiring Walt, I also took a couple of pix that I'LL post. Lets call the Transformer end of the picture the Top and the front panel the bottom as it will come up in my pictures.
From the manual you have one of the input leads going to 110.

Move it up to 117 VAC at the TOP.

In the center as per the book the Zero side is connected to the next 110 contact.

LEAVE THE ZERO contact where it is and move the lead from 110 up to 117VAC contact.

Lastly you should have another ZERO contact at the bottom
(Nearest the front panel) LEAVE IT WHERE IT IS.

In Summary: (The way the books says to do it)
220VAC Europe ... eSmall.jpg

234VAC USA (Both 117VAC primaries in series) ... ASmall.jpg

You know the old saying a picture is worth a thousand words.
So this should clarify this once and for all.
Carol W4CLM

OH & PS:
By the way that extra jumper you wind up with when going from 117 to 220, just double it up so you don't loose it. Better not to have it flopping around in the amp some place. It won't hurt to do this note the center contacts. Save that extra jumper lead if you have one in case you
ever want to wire it back to 117VAC. Just do this. Shown for Europe 220VAC. ... pSmall.jpg

PostPosted: Wed May 09, 2007 6:32 am
Hi to all
Its Very simple .( 100 volts 1 phase for japan) (220v 1Phase Europe),
( 117volts 1phase 60hz USA) These Voltages are mesured from
ground in the countrys above . Take in mind the 2100b has a fuse
in only one side of line.. If it were made for 220 Or 234 Volts USA ,
It would require both sides of the 220-240v line to have fuses .One
in each line of the cord , as the 240 vac system in the USA is
120 volts above ground to L1 And L2 of power cord ...
So if you connect the 2100b For 234Volts as shown in carols photo
it will work .. But it would be My advice to feed it with a breaker or
proper fuse box not exceeding 15 amps . ( Say you were to connect it
to a larger circuit of oh' 25 -- 30 amps or more you would have one side
of the line unprotected in the amp this could cause at the least a burned
connection ,if you had a short in the unfused line . some thing to think
on . the idea of two fuses is not mine it is required by the national electrical code and also is in basic wire circuits in most arrl hand books .
till later .

Good show mate

PostPosted: Wed May 09, 2007 3:57 pm
by W4CLM
Thanks Sid,
I knew if we were to shake the apple tree hard enough, we would eventually get a statement out of you on this subject.

The fuse situation makes a lot of sense, like you say it should have a fuse on each leg to truly be protected. The way it stands with only one fuse for 117VAC then we only have only one leg of the 240 AC line protected and roughly 117 VAC on the other half of the line coming in is not protected.

Carol W4CLm