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Author Topic: SB-220 amp 120 volt vs. 240 use  (Read 5652 times)
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KK4RF
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« on: January 05, 2010, 02:44:41 PM »

Gentlemen:
     I was recently given an old Heath SB-220 amp. It needs cleaning and new filter caps, diodes, etc... I'm soon to place an order with Harbach for all this stuff.  It is said to be working OK. It is wired for 220-240 volts for the primary but I'm told it can be wired to run on 110 volts. I intend to use mine to follow an HT-40 xmtr (controlled carrier AM). I don't have a 220 volt line into my shack. I really don't plan to run the amp very hard. Is anybody on-line here running one at 120 volts? Anybody with heartburn doing this? I could hire an electrician to run a 220 volt line, but I was hoping to avoid the fuss and expense.
     This should be a fun project. All opinions greatly appreciated.
     ---Marty, KK4RF---
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KD6VXI
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« Reply #1 on: January 05, 2010, 03:17:26 PM »

20A is fine for the SB220... Smiley  On 110.

2Kw input = 20A, give or take, at 110.  You'll probably see about a 10-15 amp draw, honestly.



--Shane
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DMOD
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« Reply #2 on: January 05, 2010, 04:22:59 PM »

You can use it on 110, just change jumpers. For comparison, my Henry uses ABC 15 Amp fuses in each line for 220V operation.

Make sure the outlets and wiring can take it and the circuit breaker is up to par.

Too many houses these days are running small diameter (large guage number) wiring and there is a lot of voltage drop and hence power loss, in the lines.

I am glad to see you're wanting to upgrade and keep this boatanchor.

Phil - AC0OB
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« Reply #3 on: January 05, 2010, 04:26:58 PM »

I always ran mine on 240 VAC but 120 VAC will probably be OK if you have a good wiring system in the house.

1920 VA (16 Amps) is all that you are supposed to take from a 120 Volt 20 ampere receptacle circuit for a continuos load. You will be iffy if you have a 15 ampere circuit (#14 wire)

Try it and see. If you end up with flickering lights, you may need to run it on 240 volts.

Pat
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WQ9E
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« Reply #4 on: January 05, 2010, 04:28:58 PM »

Marty,

As long as you have a "stiff" 120 volt line running to your shack, the SB-220 will run fine on 120.  BUT, you really want the wire back to the box to be 2-12 and not too long a run of it.  Furthermore, the SB-220 should be the only item on that branch circuit.

Realistically, most shacks don't have a heavy dedicated 120 volt source so it is just as easy to run a 240 volt circuit if your 120 line isn't up to the load.  Another option would be to limit the input power to around 1 KW but still avoid having other items running off this circuit.

My philosophical view (for what it is worth):  If you plan to be in your current QTH for more than a year or so bite the bullet and have a 240 volt line installed now so you can enjoy the SB-220 and any other heavy duty gear you might add in the future.   Dealing with insufficient AC power to the shack will detract from your overall enjoyment of the hobby.  Blinking lights and tripping breakers will greatly reduce other household member's tolerance of your hobby (or you in general if a key breaker trips at an inopportune moment-some of you probably remember some of the creative commercials by Phillips indicating what could happen when a light fails at the wrong moment  Smiley

Rodger WQ9E
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Rodger WQ9E
KK4RF
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« Reply #5 on: January 05, 2010, 06:52:24 PM »

Gentlemen,
     Thanks for the advice. I'm not sure what I'll do, but I'm leaning toward running it on 110 volts. My SB-201 does OK on 110 volts. The SB-220 seems so much bigger, though.
     The first hurdle,  however, in this venture to refurbish this fine old amp is to convince my wife of the necessity of spending the $225 needed to buy the new power supply parts plus a new fan and the soft-start module necessary for the job. Somehow I'll get it done.
Thanks again. ---Marty, KK4RF---
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Jeff W9GY
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« Reply #6 on: January 05, 2010, 07:33:57 PM »

You can get your parts from Harbaugh if you like, but believe me, ordering them from Mouser will save you at least 50%.  I've done two SB-220's in the last year.  Regards Jeff W9GY
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Jeff  W9GY Calumet, Michigan
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« Reply #7 on: January 05, 2010, 08:53:11 PM »

Considering that you can only operate that amp safely (and cleanly) at around 350W out on AM that means a hair over 1000W input and you will be heating up the shack with the other 700W. So a 120V line will be OK. Just dont get into old buzzard transmissions as the power transformer isnt rated for that sort of abuse.

The fan motor is very easy to take apart, clean and lube. Just be sure to replace the blade as per the manual.  No need to spend on a new fan unless you need a higher speed one for graphite tubes.

Filter caps can be from Mouser as mentioned, the CDE 381LX 330uF @ 450V fits the blocks perfectly and they are 105* C rated. Another option is to buy them from Ameritron who has 270uF shorty computer grade that also fit perfectly.  In any case replace the equalizing resistors with 75K 3W MOX.

Replace the PS diodes with 1N5408's and drill out the holes to fit. Unless you have other problems there is no need to buy a new PS board.

Dont tell the wife you saved money, treat yourself to something you want Grin

Carl
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ke7trp
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« Reply #8 on: January 06, 2010, 01:03:08 AM »

There is no way you can run 350AM on an SB220.   Forget that right now.  The real limit of this thing is more like 200 am. Maybe 250 if you feel lucky.

I have owned 4 of them. I still own 2.   I have ran them on 120 volt houshold lines but performance suffers.

I have had an electrician run a real 30 amp 120 volt line into the shack and a 50 amp 220 volt line.  Before I had a chance to change the jumpers and wire the plug, I ran it on the 30 amp line.  This is what I found:

On the standard wall socket, I was hard pressed to get 800 watts.  My Shack is far from the breaker box across the house. Lights dimmed in the room.

On the 30 amp line, I got about 1000 watts out pep.

On the 220 volt 50 amp line the amp sings right along at 1300 watts output. If I Drive it hard, I can get 1450 out but I am really hitting it.

Even on the 220 volt line,  AM is a killer on this amp.  The Power trans is small and taxed.  Many of failed.  Massive heat boiling out of the thing also makes me run it down a bit. 

Mine has the Harbach Caps, Diode board and meter board. I built and isntalled all this on the bench in a saturday.

The big thing to remember here is to use low Drive and the tune position to tune.. Then gradualy increase the Drive. The air cap is very easy to arc over and if you hit it to hard just slightly out of tune, Thats it.

Clark
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KM1H
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« Reply #9 on: January 06, 2010, 12:35:52 PM »

Quote
There is no way you can run 350AM on an SB220.   Forget that right now.  The real limit of this thing is more like 200 am. Maybe 250 if you feel lucky.


The real limit is 1000W input for continuous carrier operation, read the manual. With controlled carrier and no old fool transmissions that limit wont be close to being exceeded. At 1000W input it can easily be run from a standard 120V 15A service using a quality duplex outlet....not a discount store special. Or a single 20A outlet if you want.

For AM the goal is to remove the excess tube heat which can be helped by a Harbach or other higher speed fan motor if found necessary.

Excessive transformer heat can be mitigated by a muffin fan but Id be more concerned by the leakage of the filter caps which doesnt show on the plate meter. Leaky caps and low value equalizing resistors need to go before anything else.

Ive run a SB-220, LK-500, NCL-2000 and several other amps with 800-1000W of plate dissipation for years in the past as AM linears running around 350W output which is where they look good on the scope. Never had a failure as its all within spec.

Carl
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K5UJ
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« Reply #10 on: January 06, 2010, 12:44:34 PM »

I've been running the ten tec Centurion at 300 w. with a dahl 1/2 A ccs plate trans. and 180 CFM fan pulling air in through the plate supply and blowing out across the RF deck.  Made 10 to 20 minute transmissions with no problems but still want to build an outboard plate supply.   At 300 w. dead cxr Ip is just a tad below 400 ma. (according to the front panel meter), around 380 ma.  Ep is 2.7 or 2.8 KV
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N4LTA
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« Reply #11 on: January 06, 2010, 01:51:48 PM »

FYI - A 30 amp 120 volt branch circuit is only code legal if it terminates in a single NEMA rated 30 ampere 120 volt receptacle to serve a single dedicated appliance. If it terminates in a single or several standard 120 volt 15 or 20 ampere receptacles - it is not allowed by the NEC.

You can run #10 wire from a 20 ampere breaker - but that is not a 30 ampere branch circuit - that's a 20 amp branch circuit.


Pat
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WQ9E
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« Reply #12 on: January 06, 2010, 01:59:23 PM »

The controlled carrier AM rigs, like the original poster's HT-40, are very linear friendly.  The SB-220 will work fine with it but you do need enough AC power capability to prevent flickering lights and other issues on peaks.  I have heard some very nice sounding Knight and Heath low power AM rigs on 75 driving modern amps.  The controlled carrier rigs can sound very good and they are plentiful and inexpensive.  I bet a lot of new generals really had fun getting on "phone" with their old novice rig and their new ticket.

Any of my Drake 4 lines work well with my L-4B in the AM mode but I have to be much more careful using the TR-7A/L-7 combo because the 7 line is full carrier with one sideband unlike the older 4 line which is controlled carrier.  To add insult to injury, the cooling system in the L-7 is poor compared to its older brother.  

None of the traditional 2KW pep amps are really up to 375 watt carrier output i but I imagine the Alpha 77 (especially the dual 8877 model!) would do quite well.  I have used my Viking 2 with my homebrew amplifier at the legal limit but I wouldn't try it with any of the other amps I have around.  On the other hand, running an SB-220 at 150 watts carrier out driven by a high level plate modulated transmitter is well within its capabilities and is only a few DB down from the legal limit.   I will happily give up a few insignificant DB on the S meter at the other end to save the finals and power supply.  If we ever generate enough AM activity for a real DX contest using AM then I will use one of the legal limit rigs or my HB amp for that and take every DB I can find!

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Rodger WQ9E
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« Reply #13 on: January 06, 2010, 05:02:41 PM »

Roger, Ive run my Alpha 76 3 holer a few times driven by a backed down 5100 and Viking II on 10M. With 1200W of plate dissipation and the optional Dahl xfmr there is no overheating anywhere even after a few hours of ESkip pileups. Carrier out was right around 375W. This was a Carribean contest amp that has always been pushed hard in less than ideal enviroments before I got it and I was curious about its AM capability.

Most of the AM linears Ive run into are also driven by CC or a SSB xcvr with one sideband. Once adjusted they sound fine.

Id really like to try an Amp Supply LK-800A with its 2400W of plate dissipation or one of those 3CX3000A7 Henrys. Shocked

A heavy metal AM contest would be fun as long as there was serious activity and not just a couple of BCB rigs and pampered KW-1's. All power levels welcome but mainly get those old time homebrew big rigs fired up again.

Carl
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KD6VXI
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« Reply #14 on: January 06, 2010, 05:20:05 PM »

FYI - A 30 amp 120 volt branch circuit is only code legal if it terminates in a single NEMA rated 30 ampere 120 volt receptacle to serve a single dedicated appliance. If it terminates in a single or several standard 120 volt 15 or 20 ampere receptacles - it is not allowed by the NEC.

You can run #10 wire from a 20 ampere breaker - but that is not a 30 ampere branch circuit - that's a 20 amp branch circuit.


Pat
n4lta

That's interesting, and thanks.  I was ABOUT to reappropriate the dryer outlet.

OK, if that's the case, what about this?  Your own "BOB", BreakOut Box?  I've built them for years for powering the shack from dryer outlets, old stove outlets, etc.  Would that screw you?

Thanks, in advance....  Fortunately, the old 220 dryer outlet is 6 gauge, and terminates exactly 4 feet from the Harris Sad

--Shane
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KD6VXI
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« Reply #15 on: January 06, 2010, 05:25:42 PM »

Roger, Ive run my Alpha 76 3 holer a few times driven by a backed down 5100 and Viking II on 10M. With 1200W of plate dissipation and the optional Dahl xfmr there is no overheating anywhere even after a few hours of ESkip pileups. Carrier out was right around 375W. This was a Carribean contest amp that has always been pushed hard in less than ideal enviroments before I got it and I was curious about its AM capability.

Most of the AM linears Ive run into are also driven by CC or a SSB xcvr with one sideband. Once adjusted they sound fine.

Id really like to try an Amp Supply LK-800A with its 2400W of plate dissipation or one of those 3CX3000A7 Henrys. Shocked

A heavy metal AM contest would be fun as long as there was serious activity and not just a couple of BCB rigs and pampered KW-1's. All power levels welcome but mainly get those old time homebrew big rigs fired up again.

Carl
KM1H

Carl,

The 8K Ultra is a great amplifier, but not capable of 2Kw of carrier.

It likes to run about 1200 to 1400, if you want to remain clean, not have loads of intermod, etc. 

The LK800 I've not had the pleasure of operating, but I have done a Commander HF2500E.  It's also 2400 watts, 3 800 tubes.  It had NO problems making 6 thousand PEP, into the Altronics, of course.  Funny, it would darn near SMOKE the 8K ultra.

The 8K is a good amp, for general use, but if you want a great amp that actually exploits the tubes potential, that's not it..  I don't know of a general 3x3 built FOR amateur useage.

The 3K Ultra was OK, I (as everyone knows) don't like the 8877.

But, when you think about it, Henry amplifiers are about the most abused amps by the CBers, so it does speak volumes about them when you think of they way they where usually (over)run, etc.

--Shane
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WQ9E
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« Reply #16 on: January 06, 2010, 06:03:36 PM »

Roger, Ive run my Alpha 76 3 holer a few times driven by a backed down 5100 and Viking II on 10M. With 1200W of plate dissipation and the optional Dahl xfmr there is no overheating anywhere even after a few hours of ESkip pileups. Carrier out was right around 375W. This was a Carribean contest amp that has always been pushed hard in less than ideal enviroments before I got it and I was curious about its AM capability.


Carl
KM1H

Carl,

The 3 hole 76 is a nice amplifier and I think it is a definite step above most of the "legal limit" amps of the day.  They probably really would stand the brick on the key test in their old advertisements.  I picked up a much less capable Alpha 274 last year at a hamfest.  It did come with a pair of nearly new 8874 tubes and works fine and for $200 it was quite a deal.  But it will ultimately be paired with a Signal One CX-7 when I get it running properly running mostly SSB and CW.

I visited one of the deep south contest stations in the mid 1970's and it was running multiple Alpha 77SX amps.  But prior to that the owner used Heathkit SB-220 amps and they stood up to contest usage OK also; they were run with the external case removed and an additional fan which probably greatly helped the reliability.

Someone on Hawaii purchased several Henry 8K ultras for a contest setup a few years ago but I didn't keep up with the story.  They should do a nice job on AM.

It would be fun to recreate some of the older contests and keep the multiple power and band categories to encourage a broad variety of rig usage.

Rodger WQ9E

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Rodger WQ9E
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« Reply #17 on: January 06, 2010, 06:04:06 PM »

If it were me - I'd put a small panel 4 or so spaces - you can get one at Home depot and put some 20 amp breakers to make the breakout box. Or just install it one the end of the dryer wiring and acll it the shack subpanel.

Or maybe just wire up something safe - the problem is almost all receptacles are 15 amps (even used on a 20 amp branch circuit) and if you overload one to 35 amps or so it can overheat. Most any residential circuit breaker will hold 120% of rating for hours. That is why the code does not allow 30 amp receptacle circuits without a dedicated 30 amp receptacle.

If you have a single receptacle 20 amp circuit - you must terminate it in a 20 amp receptacle - 15 amps receptacles are only allowed on a 20 amp branch circuit if you have two or more receptacles.

20 amp receptacles are available at Lowes and Home Depot but are not the normal lower cost ones everybody uses including builders.

Pat
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« Reply #18 on: January 06, 2010, 06:59:22 PM »


Carl,

The 8K Ultra is a great amplifier, but not capable of 2Kw of carrier.


I may have missed something but I don't recall Carl expressing a desire to run a 2 KW carrier.
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« Reply #19 on: January 06, 2010, 07:23:28 PM »

Quote
The LK800 I've not had the pleasure of operating, but I have done a Commander HF2500E.  It's also 2400 watts, 3 800 tubes.  It had NO problems making 6 thousand PEP, into the Altronics, of course.  Funny, it would darn near SMOKE the 8K ultra.

And to think that I had a customers Cary LK-800NTA with the 2500/3500V PS in here last month with brand new 3CPX800A7's. It was in here to be converted from a No Tune to a regular tune amp for a contest station. It sure impressed my 5KW slug with only 100W drive but I didnt have the nerve to try it on AM Cry  With Bill Edwards of Omega gone Im getting a lot of the Amp Supply work in here.


Pat, when I wired this place in 89 (legal for a homeowner in NH) I ran #12 to every outlet and with almost twice the number of outlets normally used. Nothing gets overloaded, I just dont like blinking lights and the house covers a lot of area. A 200A panel was filled up with 120V 20A and many 240V 20-40A circuits. The outlets used in the living areas were the case lot builders grade 15A; the basement and kitchen were the heavier duty ones with more copper and a positive feel when a plug is inserted. Ive replaced 8-10 of the cheap ones the past few years, plugs would simply fall out.  One thing I will not do is use those strip and push in the wire outlets. Everything here was done the old wrap the wire around the screw way.

Carl
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Quote
I visited one of the deep south contest stations in the mid 1970's and it was running multiple Alpha 77SX amps.  But prior to that the owner used Heathkit SB-220 amps and they stood up to contest usage OK also; they were run with the external case removed and an additional fan which probably greatly helped the reliability.


Back before they became big $$ collector amps I did my share of work here on repairs and conversions to SX with Alphas blessing. Customers didnt want to ship and cant say I blame them
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N4LTA
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« Reply #20 on: January 06, 2010, 07:53:26 PM »

Actually there are some very good 15 amp 120 volt receptacle. My favorite is the back mount receptacle that you insert the stripped wire and tighten a screw to retain it. It stops the unfortunate touching of the side screws. They are a little more expensive but I just helped my son rewire his house and I love them.

What I was trying to say is that 15 amp receptacles are standard for a 20 amp circuit UNLESS you have only one dedicated receptacle - then you must use a 20 amp receptacle.

On a 30 amp circuit - you can't put any receptacle on it except a bastard type NEMA 30 amp receptacle (that a standard plug won't fit).

In a residence - you can actualy put as many receptacles on a circuit as you wish. The code just specifies how many circuits you must have (as a minimum).

In a commercial or industrial  establishment - you have to count each duplex receptacle (called a strap) as 180 VA load and are limited to 1920 VA per 20 amp circuit.


Pat
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KK4RF
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« Reply #21 on: January 07, 2010, 12:42:09 PM »

Gentlemen,
     Thanks for the great response to my question. Lots of great ideas to digest. I'd like to do a 220 volt line into the shack but may try just re-wiring the SB-220 for 110 volts, put a new plug and cord on it so that  I can at least give it a try. I'll let you all know how it works out. Thanks again. ---Marty, KK4RF---
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KD6VXI
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« Reply #22 on: January 07, 2010, 02:08:43 PM »

Gentlemen,
     Thanks for the great response to my question. Lots of great ideas to digest. I'd like to do a 220 volt line into the shack but may try just re-wiring the SB-220 for 110 volts, put a new plug and cord on it so that  I can at least give it a try. I'll let you all know how it works out. Thanks again. ---Marty, KK4RF---

I ran mine on AM on 110 for literally, years.  I did increase the bias voltage, though.  A series of 6A10 diodes will be indestructible for that.

I netted 300 watts PEP by going to a stiff 220 line.  IMD did improve, however.

--Shane
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