sb-221 drive

[153]

Here is a prob dumb question. Can I use my sb-200 to drive my sb-221 without damage? I have a rci2990 for my radio. I have it keying about 40 swinging to 150. That is what I would be putting into the sb-200.

[Rich]

150 watts will overdrive it already.These were designed for use with 100 watt hf rigs.
Rich

[153]

The question in my mind is when i drive it with radio drive I only get about 800-900 watts on a dosy test center. Several people have told me just keep the dead key below 100 drake watts and let it swing. I don't know. I have a neighbor that has a maco 200 driving a sb-200 driving a sb-221. he has ran it for several years. Now i'm not saying that is correct, I just don't want to blow mine. But if that is all it will do my 4 pill will run all over it. Correct me if i'm wrong please

[Foxhunter]

He's right. The majority of "Ham" amplifiers are lower-level "highdrive amps" that require at most 100W of drive/input. Feeding the SB-200 into the SB-221 will damage/destroy the SB-221. Watch it-----those 3-500Z tubes are expensive.

I have a Heathkit SB-200 and although it will take up to 100W of drive, it is better driven at about 65W to get full output 500W-600W. If you were to send 500W or more into the SB-221 it would harm it guaranteed. Atleast you have two decent amplifiers, one to use as a decent talker (220) and one to cut through the smoke a little more (221).

There really is only almost 1 S-unit difference between the two amplifiers.

[153]

Thanks for the info. i think i prob will sell the 221 and opt for a 12 pill maybe. I need some get up due to my elevation.

[PONY EXPRESS]

Well if you overdrive those 2 HEATHKIT amps you will be buying some expensive tubes.

Maximum drive to either 1 is 100 watts input and that is on ssb /cw .
I wouldn't even try it on AM unless you want a GRID short on some expensive tubes.

Here is some good info on the SB-221

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[153]

OK now let me ask this. I know not all watts are created equal. If I put 100w into it by my dosy I get 1,ooo out. I have a drake meter (w4) so should I put 100 "drake" watts into it because that is a more accurate reading. I know there is alot of difference between the two.

[Foxhunter]

OK now let me ask this. I know not all watts are created equal. If I put 100w into it by my dosy I get 1,ooo out. I have a drake meter (w4) so should I put 100 "drake" watts into it because that is a more accurate reading. I know there is alot of difference between the two.

Some are using two different types of measurements for "wattage" readings.

1-----True "Root-Means-Square" (RMS) power aka "Average" (AVG) power

2-----"Peak-Envelope-Power (PEP)

PEP Peak power ratings refer to the amount of power an amplifier produces or can handle, for a brief burst.

RMS power describes the amount of continuous power an amplifier produces or can handle. The RMS power rating is always the more significant number, as it is a more accurate reflection of a unit's performance in everyday continual use.

In other words peak envelope power is the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope, under normal operating conditions. RMS power and average power are the same value.

As a rough guide often RMS is about 1/2 of the PEP value.

The watt meters themselves will vary with accuracy from manufacturer to manufacturer. Note the type (RMS or PEP) of measurement the meter is using.

Dosy meters are known for being a tiny bit generous and are definitely "PEP" reading meters.

I don't own a Drake but their products were good and pretty well-known and if the meter is still accurate I'd prefer that one over the Dosy.

There is a review of the Drake W-4 at the following link including a post mentioning its use with a very similar to yours Heathkit SB-200.
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There is a review of the Heathkit SB-200 also at Eham here:
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There is an descriptive article and schematics too of the Heathkit SB-200 also at here:
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There is a review of the Heathkit SB-220 & SB-221 also at Eham here:
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Also read this more detailed review of your Drake meter here:
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PEP AVG RMS explanation
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[153]

thanks so do you think i need to input 100 wats of drive going by my w4 drake? If I put 100 rms watts into it and then put it on my dosy it will do over 2500 watts. Or about 1600-1700 on my drake. i may be going about it all wrong. I have a 6 pill that seems to output more than my sb221. is this correct?

[Foxhunter]

thanks

so do you think i need to input 100 wats of drive going by my w4 drake?

If I put 100 rms watts into it and then put it on my dosy it will do over 2500 watts.

Or about 1600-1700 on my drake. i may be going about it all wrong.

I have a 6 pill that seems to output more than my sb221. is this correct?

It seems that the Drake W-4 is capable of reading measurements from 0-200W and from 0-2000W forward power on the each scale.

I do believe (anyone correct me if I'm wrong) that the drive/input levels for these amplifiers are measured "PEP" or in other words "swinging up to 65W or 100W". Not a "deadkey" of 65W or 100W and swinging up from there.

I would keep the "drive" input maximum PEP ("swing") levels near or below 100W PEP. Most people recommend driving "it easy" at 65W of drive and others drive "it harder" at 100W of drive.

The 6-pill you have I am not familiar with as far as if it is a straight 6-pill with all 2SC2879's or is it a 2x4 with two 2SC2290's driving four 2SC2879's or what you have. I'll take it that it is a Class C amp. Although I think that six 2SC2879's (rated at 120W each) will only total around 800W guys claim to get much more out of them but I'm not sure what measuring method exactly they are using. By increasing voltage you will get more. I have two DaveMade 2x4 amps and they are good for around 1000W by pushing them a little.

I'd think that the SB-221 would rival the 6-pill without much problem. Besides it's much more versatile and also SSB capable, as well can be tuned etc. Very flexible and is forgiving to operate. You will get better reports back often with a tube radio or amp. I myself am waiting for 220V to use a couple of my tube units and I will switch over to them more as I rotate my radio's & amps often.

One more thing let me list a link to a thread where I first asked about my Heathkit SB-200 when I first bought it. Some of the guys here had some recommendations for me as I was unfamiliar with the unit entirely. Here's the topic link:
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After reading quite a bit after their suggestions on the "Harbach Mods" for the Heathkit amps I would say that they would be a recommended upgrade. Many of the reviewers on the Eham links I provided earlier also mention doing these upgrades. Go to the following page at the link below and when you get there you will see two listings on the left sidebar for each pair of amplifiers (the SB-200 & 201 and the SB-220 & 221). I'd recommend reading this:
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[Night Crawler]

If you drive that 221 with 100 watts rms for more than 30 seconds the plates in those tubes will start to turn cherry red. That amplifier is rated for a 50% duty cycle ssb and cw. Read the info on the links that were posted. That amplifier was never designed for use on am.

[Foxhunter]

If you drive that 221 with 100 watts rms for more than 30 seconds the plates in those tubes will turn cherry red. That amplifier is rated for a 50% duty cycle ssb and cw. Read the info on the links that were posted. That amplifier was never designed for use on am.

Hey Nigh Crawler glad to see you and I hope all is well "up there" in the Northern suburbs. Hope your Thanksgiving holiday went as it should!

This is good advice and true SSB is highly utilized in Amateur Radio and used far more often than any AM transmission. The following guys here I believe are very familiar with this type of AC unit:

Night Crawler

NCMidnight

Circuit Breaker

Red Warrior

......to name a few and I'm sure I may have left some out!

PM them or perhaps they will see your post-------but I'd listen to/follow their recommendations.

Foxhunter

[153]

Thanks for all the info. I never use ssb only am. i may come out better selling and getting something different. Everybody locally says input 100 watts and swing 400-500. But I thought that was a bit much. I in no way want to damage my sb as it is what i consider mint. I am just going to sell it to someone who can use it for its intended purpose.

[Night Crawler]

Everybody locally says input 100 watts and swing 400-500. But I thought that was a bit much.

I think what they were trying to tell you is that you can drive that amplifier until you get a resting carrier or dk of 100 watts out of the amp with 400-800 watts pep or swing.
Here's an example it's a modification to a ham transmitter to enable you to use a legal limit amplifier on AM and stay within the ratings of the the tubes. I used it myself on a dx40 that I use on 75/80 am phone and it worked very well.

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You can drive a pair of 3-500z's pretty hard on AM and see well over a 1000 watts but the downside is they won't last very long.

[153]

great info...that is why i asked yall. They are saying drive it wih a maco 200 or a sb-200. I do not feel safe doing that. Now I also was "told" 3-500z are 500 watt tubes. I have a neighbor running a jb-2000 driving it with a 4 pill (keying 20 swinging 600) into it. Been doing it for years. But I value my sb as it is near perfect. I just ASSumed when i bought it i could run am and get about 2000+ out of it. I have a guy close by that says he can do a little modifing and add 1 more tube and it will be good for 3500 plus. Like I say I am going to sell and get a am amp. Got my eye set on a 12 pill.