The AM Forum

Brought home a new to me Heathkit Chippewa today.  It is complete but very dirty.  I think the best thing to do is re-build her from the ground up.  Although it was supposedly working before it was put away in storage.  I'm starting this thread to document the restoration process.  I will likely need the collective input of ya'll as I do this re-build as I have never done a restoration like this.

Here are the pics, this is how I brought her home:

Front view:
http://n1ese.qrpradio.com/AM/Chippewa-1.jpg

Top view:
http://n1ese.qrpradio.com/AM/Chippewa-2.jpg

See the broken meter in the first pic?  Here's a NOS replacement:
http://n1ese.qrpradio.com/AM/Chippewa-3.jpg

- JT

How's the power supply section?

Turned out to be homebrew, I was hoping it was the matching HS-1 but it's not.  Here are some pics of the HV supply that came with the amp:

Transformer:
http://n1ese.qrpradio.com/AM/HVSupply-1.jpg

Capacitors:
http://n1ese.qrpradio.com/AM/HVSupply-2.jpg
http://n1ese.qrpradio.com/AM/HVSupply-3.jpg

- JT

Dude, that's a helluva strapping PS  ;D ;D

Tell me about it, I can barely lift the transformer.  I need to figure out how to safely discharge the capacitators before I kill myself working on this stuff.

- JT

Matching supply was model KS-1.

Hopefully you got a schematic of the power supply to get a feel as to how it was designed. Hard to tell from the pictures you just posted. Actually I probably would be more concerned with the supply then the KL-1. Other than the broken meter, it just looks like it needs a good cleaning and component checking.

Fire hydrant red. Cool!

Unfortunately, no skizmatic for the supply.. it was basically the transformer, capacitor deck, and a few terminal strips inside the rack cabinet.
 
- JT

Should be easy enough to trace out and make your own schematic.

How do i go about identifying what all the terminals are on that big transformer?  There are a couple terminals on the other side of the transformer as well.  I also have a big mod-iron with a bunch of terminals I need to identify as well.

All this is much different than the QRP rigs I am used to building but I know to be careful with high-voltages. 

- JT

Yeah, I know I'm an idiot but we all have to start somewhere and I am capable of learning.

- JT

Negative.  On the other side, we have three terminals.  Two of them are about half way up the side and centered on each half of the transformer.  Someone hand wrote "sec." on each of these.  At the top of the transformer is the third terminal with a big ceramic insulator.  Both halves of the transformer are connected to this point and someone hand wrote "C.T." with an arrow pointing to it.  So it is clear these are the secondaries with a center tap.  No other connections are on this side of the transformer.

Thanks

- JT

I will throw out a guess, 3 phase primary...  If my guess is correct, not to fear because the transformer can still be used on a single phase line with slightly reduced ratings and I don't think that would be a problem given the size of that piece of iron!

Rodger WQ9E

Hi Mack,

The H marked terminals seem to be typical of some three phase units so that was the reason for my guess.  Hopefully if it is 3 phase someone can offer expertise in that area.  There is an article in the May '95 Electric Radio starting on P.8 that offers some information on connecting/using 3 phase transformers to single phase lines.  JT, if you find that you have a 3 phase unit and you don't subscribe to ER I can make a copy for you.  However, given that you have jumped into vintage with both feet you might want to call the nice folks at ER and get a set of back issues since you will find them full of interesting and informative info!

Rodger WQ9E

Definitely, that is why I am trying to figure out what I am dealing with first.  I don't have 220VAC in the shack yet so I won't be applying power anytime soon either.  I'll ohm it out when I get it in the shack (hopefully tomorrow).  I can barely lift it, it is still on the porch, and we nearly broke my dolly when we tried bringing in the rack cabinet and the transformer.  I'm going to U-Haul tomorrow to get a hefty dolly.

- JT

Actually, the power supply project may have just come to a grinding halt.  Does this look like a leaky cap to you guys?

http://n1ese.qrpradio.com/AM/LeakyCap.jpg

Thanks

- JT

BTW, that strap is a capacitor.  Can't tell from looking at the pic.

- JT

Sounds good, thanks Mack.  I'll wait until I discharge the caps.   8)

- JT

yeah hat looks like a leaker to me. just remove it. unless it's cap input it wont amount to anything. check it, but dont despair unless the voltage rating is exceeded or it's a cap inpoot suckply.

I would worry more about making that thing safe than makin it work for now. I think the way it's made it's a deathtrap waiting to happen. you got a lot of cleanup on that RF deck to worry about before you even fire the supply, unless you like the smell of carbon tracks, becuase that all you will get.

1. see how the supply is made. make a bangstick for yourself to discharge the caps.

2. document. dont assume the builder knew what he was doing. assume the exact opposite, that you can and will do it better than him.

3. start figuring out how you want it to be laid out.  Personally, I would turn it into a Henry Radio pedestal type all in one unit, self contained, on big casters.

(http://www.radiodan.com/Henry/images/3k.JPG)

make the framework out of 2 X 6" and wrap yer sheet metal around it. But get that supply and cap bank under cover. Unless you wanna b a SK.

btw, the pic comes from the best place to get a used henry amp in the country. the one in the pic is a bargains - -such amps are lifetime buys.

Yeah, I have no plans in the near future to make this power supply work.  It's obviously setup for 220VAC 3-phase and I definitely don't want to deal with getting that in the shack at this time.  I'm just trying to figure out what the heck it all was/is.  I will likely build a smaller supply for use with the Chippy.  The Chippy needs 3000VDC, 450 ma.  I have a feeling the power supply that I have now it much beefier than that.

- JT

 

How should I go about discharging these two capacitor banks?

One person told me to just lay a screwdriver across the bars.  However, this would likely result in the screwdriver becoming welded to the bars wouldn't it?

Should I carefully remove each bar and deal with each capacitor individually?

Once discharged, I'm putting this mess aside for awhile.   :-X

Thanks

- JT

Seems like a resistor mounted to an insulated stick is probably the best way to handle the situation?

- JT

You mean fire hydrant yellow?

I don't think that's a 3ph tranny there. I have big 3ph open frame chunks here and they all have 3 windings, or cores, or whatever. Judging by where the taps are going into the windings on the primary side, that trans looks like it has a nice selection of outpoot voltages.

Does that RF deck still have the 4x4's in it, or did someone knock it up with some 500z's? Can't see a 4-400 base in the pic.

Looks like a nice score and what will be one helluva power supply when your done. Very first thing I would do is break apart that bank of caps. Having those long large straps across the tops leaves way too much "accidental contact area". Tying them together with that 1" bar stock is useless anyway, We're talking about Kilovolts here, not Kiloamps. :P

Start at the tranny and get a nice print drawn up, and when you get to mounting the caps, wire them up with HV wire leaving the only exposed area's right at the terminals. I like to use GTO-15, it's a 14ga. neon sign wire that's available everywhere cheap.

I believe the original PS was a choke input, but that doesn't mean nothing now. It's clear this PS is wayy hairier than the original stuff was.

I would pick up a HV probe, like a Fluke 80K, and when you make your Jesus stick, a resister type is good, but make sure you also come up with a way to dead short everything right to ground. Don't use cheap clip leads to tie cap terms together. The roachclips don't have enough bite to hang on if they get bumped and can come off when your not looking. Make a set with some high quality battery clamps. Build your safety gear as though your life depends on it not to fail. Because it does.

 

Yup, here's a picture:
http://n1ese.qrpradio.com/AM/4-400A.jpg

Says Eimac 4-400A on each tube.  The amp is very stock and complete, just very dirty and the face plate is discolored with lots of nicotine buildup.

Thanks for the other comments.

- JT

Wires from resistors to caps have been cut at some point so I can't take that chance.   :o

Just pulled the bottom cover on the Chippy, more pics coming up.  it looks like there has been one mod made to the rig as there is a MOSFET installed in the LV supply area.

- JT

Yeah, I'm going to check it out later today.


Yeah, that's the best plan I think.  Build a dedicated supply, I think the original builder had several amps or modulators in mind when he built this beast.
 
- JT

Well, other than being dirty as hell, it looks to be in decent, restorable shape at least. The panel should clean up nicely and buff to a shine, can't tell what the chassis has on it, maybe just oil from the blower and accumulated dust?

Tubes look like they were ridden hard and put away wet, though. Maybe it's just the lighting. Hold a piece of white paper behind them and take a peak. Brown staining and spatters don't mean the tubes are bad, just driven hard. 

Good deal to get the replacement meter with it. The case might not be difficult to find, but the scale would be another story. I'm guessing you got the cabinet with it, just took it off for the shots?

Make a decent cage to cover the PS with. Something stout to keep things at a distance. You might find an original supply for it someday, but at least this one should work well in the meantime. Production figures I heard were in the multiple hundreds, can't recall exactly.



One of these sold at Deerfield for $450, complete. W1DEC sent it down the road along with his 75S-3B and a few other trinkets. I never cared for the looks of 'em, along the lines of a HB linear in a 30S-1 case. Always liked the Alphas, kinda miss my old PA-77 some days. The original 'brick-on-the-key' amp.

JT,

The guy I got it from was planning on building a modulator, and he sized the supply to power both the amp and the mod deck. I'll look through my file drawers and see if I come up with his address.

HTH.

Bill W1AC

Here are some more pics of the Chippewa with the bottom covers removed:
 
http://n1ese.qrpradio.com/AM/Chippewa-4.jpg
http://n1ese.qrpradio.com/AM/Chippewa-7.jpg
 
Some type of modification was done to it.  This is an NTE51 which is a high Voltage, high speed switch transistor.  Here's a pic of the transistor:

http://n1ese.qrpradio.com/AM/Chippewa-5.jpg
 
Some of the caps look new:
 
http://n1ese.qrpradio.com/AM/Chippewa-6.jpg
 
I just hauled in the cabinet this was all mounted in.  Pics of this beast coming up in a bit.

- JT

Some of that soldering looks like it was done by a gorilla. You sure have got your work cut out for you, but plenty there to work with.

Yep, it's a long way from the world of QRP.  ;D

Rack cabinet pictures:
 
http://n1ese.qrpradio.com/AM/rack-1.jpg
http://n1ese.qrpradio.com/AM/rack-2.jpg

Blower:
 
http://n1ese.qrpradio.com/AM/rack-blower.jpg
 
Wiring at the bottom where the HV transformer was mounted to the floor.  Secondaries were wired to the terminal strip in the first picture:
 
http://n1ese.qrpradio.com/AM/rack-wiring-1.jpg
http://n1ese.qrpradio.com/AM/rack-wiring-2.jpg
 
- JT

Wow, someone went through the trouble of painting up a relay rack to match. That's a lot of Heathkit green!   :o

Actually, upon closer inspection.. only one of the tubes is a Eimac brand 4-400A.  Not sure what the other tube is, there are no markings on it and it looks a bit different.

- JT

When you go to test the transformer, use a low voltage transformer and a fuse if you like to fire up the primary - or what you think is the primary.

In the case of a big step up like 120v:6000 CT or so, I'd use a 5 volt AC source.
Then the ratio of ~1:60 will give you like 300vac across the entire secondary... not quite so bad... I often use a 10v source since that gives you a quick and accurate reading of the ratio.

To "short" those caps? How about taking two cleep leeds from one of those resistors and putting an insulated stick on one lead, clip the other lead to one of the cap rails and take the other lead with the insulated stick and put it across. Then wait, it should be down to nil pretty quick. Put a temporary shorting wire across the bars or the terminals of the caps. Done.

                         _-_-bear

I just ordered a high voltage probe today, if I'm going to be working on this stuff.. I need one anyway.

- JT

I bet that little bit of solid state in there has something to do with the tubes idle current.

I'd take the Alphas too, but the older Henrys are damn nice amps. At $450 that was a steal.

Nooooooooo!!!   :o :o

Yes, you need a HV probe later!!

When you go to fire up an unknown transformer one definitely does not want to put line voltage on it!! Not terribly safe nor a good way to figure out the taps.

The best way is to use a small step down transformer, as I said preferably one that makes it easy to figure out the ratios later, like a 5vac, 10vac, or for those who are terminally lazy or without a calculator 12vac (10x less than line voltage). It can be rather small, nothing big needed, an amp of current rating is quite sufficient.

(or you can use a random low voltage transformer with the secondary set to your favorite voltage with a variac on the 120vac primary side of the LV transformer...)

This also works fine for finding the turns ratios on mod iron.

This lets you test without popping the breakers in the house, without sparks, without deadly voltages and no smoke.  ;D :D

                     _-_-WBear2GCR

                       

Bear, sorry.. you misunderstood and I wasn't.  I am not powering up the transformer anytime soon.  I bought the HV probe so I could see how many volts are still in the capacitor banks.  This was suggest by a few people earlier in the thread.

- JT

You can play with the HV probe no prob.

As Mack said, just take and short them out already - use the resistor.
They'll only have some minor atmospheric charge unless something wierd happened to them... the internal leakage will drain them down usually, or worst case leave them with some voltage but not backed by any Joules... usually.

Then tie them down with a few bits of #20 solid wire, keep them at ground, if you worry about such matters...  ;D

JT, keep in mind that just like a QSO on the air, the reader to poster ratio is fairly high here, so opportunities to spell out things like that are useful to others who might merely be lurking and reading the posts, and may actually go off and try some things that they're not 100% on solid footing with are valuable. In the case of high voltage high current transformers it's not a minor detail. So, I try to nail down things like this, lest someone get the wrong impression and make a dangerous or fatal error as a result.


                           _-_-WBear2GCR

PS. why wait to test the iron(s) - GO FOR IT!!

Mack, I appreciate your concern and experience.  I'm scared enough to respect what I am dealing with here as I start to work with high voltage stuff.
 

Actually, the iron will likely be going to NEAR-fest in the spring along with the capacitor bank.  I'm never going to need anything as potent as this setup.  I don't know if I even want to mess with the Chippewa.  There is an OM who contacted me who has the matching supply and he's been bugging me to sell him the Chippewa so I just might.  I'm thinking of going the Class-E route where I am a bit more friendly with solid state.
 
I'll get my barefoot screen modulated transmitters on the air in the meantime.
 
- JT

Ok, I just finished stripping the rats nest of hanging and disconnected wires from the rack cabinet.  Here are pictures of the remaining pieces of the high voltage supply.  Still not sure how this was all wired originally as everything was cut up pretty good with almost nothing attached.
 
Big honkin' relay, this was mounted right next to the big honkin' power transformer near what I believe to be the primary side:
 
http://n1ese.qrpradio.com/AM/relay.jpg

The secondaries on the big honkin' transformer were connected to this bridge rectifier panel:
 
http://n1ese.qrpradio.com/AM/diode-panel.jpg
 
Back to cleaning up the cabinet.
 
- JT

For watts its worth, I'll wrap solder around the terminals of oil filled caps, and other points of HV...Eye glasses help for thoes 'little' accidents.

 All oil filled caps in storage get the solder treatment.........   klc

Well, it turns out that my Chippewa has been heavily modified.  All the screen/bias control circuitry is missing and other parts put in their place.  I am definitely in weigh over my head now with none of these changes documented anywhere.  Not sure what to do now, guess I will sell it as a parts unit as it will be next to impossible to restore it back to original condition.

- JT

Hi JT,

I have an unmodified Chippewa and I will be happy to take some high res photos of the insides as a guide to you also.  Just let me know.

Rodger WQ9E

I'm just suddenly a bit overwhelmed and this is suddenly a much more extensive project than I originally envisioned.  There are actually chassis parts missing as well.  To do this amp justice likely would mean tearing down and rebuilding from step one in the manual.

I dunno what to do.
 
- JT

Hey Sonny,
You got yourself a serious project there!! A lot of TLC needed but you will have a very nice strong signal for AM.
It won't happen over night.
Prolly next radio season or in a couple of months if you have lottsa time and some dineros to fix/replace anything outta spec.

Very nice amplifier.....Chippewa capable of 160M??

Fred

Here's a picture of one problem area, this horizontal coil should not be here.  There is supposed to be a vertical plate here with a bunch of voltage regulator tubes and a clamp tube mounted to it.
 
http://n1ese.qrpradio.com/AM/Chippehack-1.jpg
 
- JT

Rodger, I'd greatly appreciate this.  I'd like the raw images straight off your camera as I run pretty high resolution on my screens here.
 
Thanks
 
- JT

160M coverage is the general consensus of the Heathkit reflector as well but several people told me it'd be extremely difficult, if not impossible, to find some of the missing parts I need.


I have received a few offers to buy it as is but I don't know if they are fair offers or not.  My gut tells me they are too low.  I am split quite evenly on whether to keep it or not.  I guess I just don't want to get it all disassembled and half way through the rebuild and hit a major roadblock. 
 
- JT

JT did you get my e-mail?


Brent W1IA

Just replied, it found it's way into my spam bucket for some reason.  Very weird, sorry.
 
- JT

Hi JT,

Do you want the actual RAW data files (.CR2)?  They will be from a Canon 1DM2 and roughly 8 to 10 megs per photo.  You would need software that reads the Canon raw data files.  Otherwise I can put it in Jpeg format and using the high res option the files will typically be 5 to 6 megs.

It will be Friday before I have a chance to take the Chippewa out of its cabinet so let me know what format you want and I can email them to you.

My suggestion is consider keeping and restoring the Chippewa since you are not likely to find another.  Although it may seem somewhat overwhelming when looking at everything if you break it down into a series of sub-projects then it should be quite manageable.

Rodger WQ9E

lmao, usually the people telling you it sucks and you should sell it, are the same people that want to buy it.

Your experiencing one of the great things about the internet. When you post a question about a piece of tube equipment in a forum that's otherwise inhabited by 'tube equipment junkies', things tend to move fast. The collective knowledge here with this type of gear is unlike anywhere else on the net, and these guys can have the project move from nut's and bolt's to dead key in an hour, then modulate that dead key in an hour and 15 minutes. So the thread moves extremely fast. Usually, a whole helluva lot faster than the project will actually move.

I would guess the project would seem over whelming at lightspeed, but there's no hurry what so ever. Take your time and learn the circuitry at your own pace. I would give it a good cleaning, then study the circuitry. See what was changed, what needs to be put back to normal, and learn the theory of how it works. I wouldn't dump it off just yet without giving it a go. It doesn't have to be this month, or even this year. Unless Bush sells the Aether, then it'll still be there when that Chip is ready.

SK

JT,

Another option to consider since it has been modified is you could use the G3SEK "tetrode board" to simplify the process of providing bias and screen voltage along with tube protection and modern transceiver friendly T/R switching; see:  http://www.ifwtech.co.uk/g3sek/boards/tetrode/tetrode-1.htm

I took the easy way out and used this when I built my homebrew triple 4CX-800 amp and the board worked fine with no problems.  You can download the manual and it will give you the information you need on what it provides and how to select the transformers you need to provide the correct screen and control grid potential for your application.

If you do this, please try to use existing mounting holes in the KL-1 since you (or a future owner) may decide to go completely back to original one day.

Rodger WQ9E

The Chippewa has been sold.  My "bitch" is off to be mated with someone who has the matching HV supply but no amplifier so I guess it will be a good fit.

I have a variac on the way to smoke test my barefoot screen modulated rigs and I will use these for now until I build the Class-E station I've always wanted.
 
Thanks to everyone for their guidance and opinions.  Rodger, thanks for offering the hi-res pics.. it naturally won't be necessary now.
 
- JT

WIMPY, WIMPY, WIMPY! ! ! ! ! ! ! !  ::)

that amplifier would not have been that hard of a project to resurect, as there are not a lot of small parts or intricate wiring to deal with. And with the rarity of that amp and the collectability of griefkit stuff, a very worthwile project.

I have repaired / resurected many Griefkit, Junkston, and other "kit built" pieces of equipment. Including 1 Apache that was literally a stripped out, empty chassis and a front panel. Most of the kit built stuff that I have redone was so poorly built or butched up that I completely dissasembled it anyway.

From the flavour of this thread, I kinda think you were overwelmed and intimidated by this project. It would have probably been less work to do than scratch building a low power rig as the engineering and layout work is already done for you. A leanyour amplifier is really a rather simple device.

Remember that taking on a tough project and kicking it's butt is what life is all about. Not to mention the bragging rights you EARN for doing it. Rizing to the challenge is truely what life is all about.

And besides "life's too short for QRP"

                                                    The Slab Bacon

Wotta wimp!   ::)   I'm in the process of rebuilding a Hammond HL2000 amp.  And it was no kit!  It's a state-of-the-art  3-500 amp, which was the progenitor of the B&W PT-2500A and then the Ameritron AL82.   

I'm rebuilding the time-delay circuitry, and the parasitic chokes.  Have all the parts  but need to fabricate a bracket to mount the time-delay relay.   I'm in no hurry, and expect it to take months, (if not years). I'm also going to upgrade it with  step-start, and  a new bias circuit.

At the same time, I'm rebuilding a Drake L4B.   

Hey, a guy's gotta have sumtin' to do!

Not really a matter of wimping out and I don't appreciate the insults.
 
The more I thought about it the more I just really wasn't interested in the project.  I don't really need a 1KW amp and I didn't want to go about re-inventing the wheel.  Someone came along who had the matching power supply but had been looking for a Chippewa for several years so this seemed like a good thing for both of us.
 
Now, I can go back to focusing on my Class-E 350W deck.
 
- JT

Recognizing the turn before you reach it is always a plus. ;) It can't be easy jumping from new QRP to old QRO technology if you're not comfortable with it. I know the fellow who is purchasing the amp, and he will do a first-rate job of bringing it back to life and will use and enjoy it. He's got a fair amount of work ahead of him.

As far as price, there's always someone out there willing to place a high value on something, just not willing to pay that themselves. Since you're happy with the deal, I suspect you (both) made a good choice.

(Emily Litella voice:)  Never Mind! :-[

It was not meant to be a direct insult, more kind of a friendly "poke in the ribs".  If you are that thin skinned, you are not ready for the world of AM. Between the knuckle draggers, tuner uppers, and other arrogant sideband operators that constantly jam and qwerm us, you will definately get a "case of the ass" trying to operate. You have to be thick skinned for AM work. It comes with the territory, or you will be constantly be fighting and bickering on the air.

It was very obvious by your posts that you were quite intimidated by that project. (high voltage does require large amounts of respect as it wont hesitate to kill you). You were scared of stuff that had been sitting dead for a long period of time.

Also you posted this big "here is my next project" then backed out of it after asking everyone for pointers. How does this make you look??
Like I said before I was just having a little fun with you. "If you cant take the heat get out of the kitchen."

As far as the class e stuff is concerned, everyone that has built them has had some tribulations with crapouts and popping mosfets. I wonder how you will react to that?

Just remember that rizing to whatever challenge life throws at you is part of the true joy of living.

                                               The Slab Bacon



 

I was mainly scared of the HUGE capacitor bank that is still strapped together.  Those suckers can hold a charge, and even rebuild a charge for a long time.  The resistors were cut from the banks several years ago, it isn't SAFE practice to assume they don't still have a HV charge.


And I respectfully thanked those who took the time to help me.  Some of those who helped me, publicly and privately, contributed additional advice to help me wisely decide that this wasn't a project for me at this time.  How does this make me look like a bad person?


I have a good local elmer 16 miles away who does a lot of Class-E building and he doesn't see this as a big problem.  I can deal with popping mosfets but multi-thousand volts potentially sitting in a capacitor bank isn't for me.
 
- JT

JT,

Don't mind that Slab o' guy... he's actually very nice.

As far as the big cap bank - well, it is a good excuse!  ;)
There is/was no requirement that you use that cap bank!! (or the rest of the supply parts...)
Don't know why it should scare you in particular, but perhaps you've read some bad novels late at night about large cap banks??  ::)

You could have always hung out until a suitable B+ supply arrives, complete, like at the next NEARFeast?? Think I saw a suitable one there in the Fall...

No matter what, you need to work with stuff that is in your comfort zone, so no worries mate! I just sold two BC-610s entirely because I knew that I did not have the time or $$ to make them come back to life in the style that I know I need to have. And, as Slab-o-Ham is currently doing in another thread - raking me over the coals - as I sold a reasonbly nice SX-28 at NearFEAST for the same reason. Now, THAT would have been a really sweet station, the 610 and SX-28!! droool.....

"...man's gotta know his limitations..." C. Eastwood

Would you ask the purchaser to post up here with a thread so that we can know what he finds was up with the Chippewa? I'm sure we're all curious as to what is found on this rare Griefkit piece!!  ;D

         _-_-WBear2GCR



PS. as I said, and you should simply learn for future use, all you have to do to drain that cap bank is to use two clip leads to the existing power resistor(s) and sequentially attach the leads to the caps... after all, you did already touch and move the thing to get it home, right? After that  (a while later) then some wire or solder across the terminals will make sure there is no charge sitting around. Not a big deal at all.

somebody close that ul tag!

                                          *SMACK*!

There. Got it.  :)

I think the main thing is JT, you thought you wanted to get into the big iron and discovered otherwise, for whatever reason(s). It's certainly no small step going from lightweight QRP to LARGE QRO, especially old stuff that has been monkeyed with. Slab and Ed's point is, you gotta start somewhere and it doesn't get much easier than the basic amp. Class E might seem easier, and the components sure are smaller, but you'll end up doing a whole lot more before you're done. Not a bad thing, just different.

More importantly - the AM community is a great bunch, but not what'd you'd call a bouquet of quietly-retiring flowers. I've gotten razzed on more than a few occasions myself, but always knew it was for my own good. "Why would you wanna do THAT?" and so on, more of a friendly poke or nudge to move me along in the thought process. One of my long-time friends and elmer KC1BT, former BC engineer and in his early 70s has no compulsion about letting me know when I'm being foolish/stupid/whiny, or anything else. "You could do it that way, but it's the stupid way. This is the smart way..." followed by more great info learned from years of actual applied technique and experience.

That's what you get here, for the most part. And it really is all good. The fact that you're basically a newb to this side of things and treated like one of the group says so. ;)

My whole point is that very often things arent realy as difficult as we often make them out to be. especially once we set our minds on doing them. We often take more time talking ourselves out of doing them than it would take to just do it. I.E. my SX-28 post.

that post was really meant to inspire others to try doing it. Many people are scared to death at the thought of recapping a 28. I couldnt resist throwing in a poke at Bear, since he just sold a 28.
(At least he's a good sport about it) As I have said many, many times: If I "put one across your bow" I dont expect you to turn tail and run, I full well expect you to fire one back. I am not thin skinned and dont get offended.

The point is that very often rizing to the challenge is not nearly as hard as running away from it. (or as hard as you thought it would be)

                                            The Slab Bacon

I respect what you are saying Slab, I really do.  However, this project really wasn't for me.  The Chippewa was part of a package deal I traded equipment for.  When I sat down and looked at the kind of AM station I wanted to have, a 1KW amp with a 3000VDC supply didn't quite fit.

You are right, I should have been more thick skinned and may have been if I hadn't let it discourage me so much when I found out the amp had been heavily modified. 

Thanks for everything and I mean everything.

- JT

Last time I checked, a man can sell any radio he owns, and it's nobody's damn business.

That said, we do yank each others' chains, and it does motivate. I've done more antenna work after getting told I was piss weak, and I've done more audio mods after being told I sounded like crap. Next time it might be wise to let the newbie get hip to this fact before we "motivate" him to much. ;)

JT,

I'm also an AM (and homebrewing) newbee.  I built a class e rig over the period of about 10 months based on QIX's designs.  Put it on the air this past spring.  So far I'm told I sound great and put out a good signal given my marginal inverted V antenna.  Check it out on my webpages if you like.

The last thing I'd do is put down tube gear.  It's the remembrance of the smell of burnt lint and the glow of tubes that turned me on to radio in the first place!  However for someone who doesn't have a basement full of boat anchors, no experience over 120VAC, and a want to get on the air with a great AM signal, class e is hard to beat.  Having said that I'm currently working on a nice little Eico 720 to put on the air and do some learning.  In the mean time I swing a decent maul on AM with my class e rig...  Whether it's hollow state or solid state, get into what suits you, get on AM.  Look forward to hearing you!

If there's anything I can help you with on a class e project just email me.

Karl (KD3CN)

WOW 5 pages!!!

Fred

JT,
Been away underground for the past week, but I see that you passed on that Chippewa. I wanted to mention, that it may have been converted to grounded grid linear operation, I turned down one in Seattle a few years ago that got butchered that way. Its OK for SSB, but not so great for AM, exp if you plan to high level modulate the plate voltage. Of course, high level modulation of the chippewa is already asking for arc overs, since the plate tuning cap is not spaced to handle the audio and B+ voltage.

Also, that other tube, looked completely wrong in it.

One more thing, that iron was single phase. Three phase power transformers for HV have three vertical cores of windings on them.

I have a Chippewa that has been modified also, to get rid of the dropping resistor/VR tube screen supply, instead having a small Stancor screen power transformer in it. I still need to check all the wiring as some of it doesn't look real strong for 700 VDC.

I have just gotten the matching KS1 power supply, delivered from a ham in CA, today. So I may get that monster on the air someday.

Mine too had the cracked meter, i wish i had a spare one.

Roger, WQ9E, if you have those high res photographs of your stock KL1, I would appreciate seeing them. Let me know.
thanks
John

I am helping JT and the days of exploding mosfets is behind us. There was a lot of experimentation in the early days and with the current designs it very rare to have such problems. My big rig has been flawless for more time than I can remember and I will be sure that JT has the guidance to build a quality rig.

So far he has a good start and I am confident he will come on with a strapping and stable rig.

Brent W1IA

John, thanks for the input.  Turns out that plate transformer came from Timtron initially and he kinda wants it back.  I just need to figure out how to get it to him.  I'm a pretty big guy but very weak due to health problems.  I can barely lift it off the ground.  Heh.
 
- JT

There may be some of that tomorrow when I go to fire up the HV supply I should have finished tomorrow if my relay arrives.  *grin*  Glad I have a variac.

- JT

Just received an email from W9RAN.. the Chippewa arrived in fine shape today and he is very pleased to have her.
 
- JT

<cloaking device off>

As the new owner of JTs much-discussed Chippewa, I reckon I ought to comment.  As you may have garnered from this thread, I have the matching KS-1 power supply, which I have been using as "bait" to attract a KL-1 Chippewa now for some years, and it finally worked ;-)   Since Heath sold the two separately and since most hams were probably more comfortable homebrewing a KW power supply than a KW amp, I suspect there are more amps than power supplies, and thought it would be cool to marry these two orphans up.   

I didn't think it was appropriate to jump in since I had a dog in the fight, but I think J.T. got good advice and made the right decision for him.  He says he's happy with how things came out, I'm happy, and UPS ought to be freakin' ecstatic!  I haven't yet noodled out the mods and what was done to the screen circuit, but I promise it will be after everyone gets the annual dose of turkey before I start "W9RANs Chippewa Thread"!

73, Bob W9RAN

tell us what you find and how botched up it was. 90% of all mods done to gear I have owned over 25 years was sloppily done, bad solder, bad layout, etc. they tended to just do it quick as possible and to hell with the quality of the work.

Bob,

As I said earlier, it went to a deserving operator (sort of a takeoff on the old "deserving DX'er phrase).  The photo CD is in the mail so happy "unmodding"!  As you are probably already aware, watch out for the plate current meter since it is at plate voltage above ground.  I look forward to hearing your Chippewa on the air; mine is hooked up with an RX-1/TX-1/SB-10.

 I spent tonight cleaning up the motor tuning on my recently acquired Hallicrafters ARR-7/R-45.  I really don't need the motor drive but since it is there it has to work or it will always be a nagging reminder that something doesn't work.  Of course with as many pieces of vintage gear as I have there is probably always going to be something that doesn't work...

Rodger WQ9E

Good luck with it. Hope to hear it on the air soon.

I betcha someone eliminated the scleen supplies and converted it to glounded glid. As glid dliven amps usually need some form of inpoot attenuation to avoid over dliving it.

W9RAN and group

Looking forward to a future Chippewa thread. Mine has been sitting on a shelf in the garage for ~5 years, it was gotten from Lon down in TX. He had another one that was mint, i took the worser of the two. He had a third one which was totally butchered, like a CBer had gotten ahold of it. I passed on that one. Mine has a HB screen power supply in it, other than that, looks fairly OK. All the VR tubes were removed along with the big high power resistor nearby. The blower is hanging loose, and that little pipe that blew air on the 4-400A tops is kind of flakey looking. The left meter on mine, the multimeter, is all boogered up, as the original was replaced with another brand meter, that was wedged into the same case, to match the other too, meter on the front panel. The pointer on it, is far too short though. If I can ever find  another of that Heathkit meter..... It kind of looks like the case for the meters on the old Johnson Vikings and such.

Like you, I held on to it, trolling for the matching unit, in my case, the power supply- a fairly rare find. I just got that a few weeks ago from Pat out in CA for a good price. (<$150). Its only missing bottom plate (I assume it must have had one) and the metal vented cover for the 866s. Mine has 3B28s installed. Will hand-fabricate a new cover for each.

That Chippewa is a monster compared to the often touted Johnson Thunderbolt that also used 4-400As. There was a great series of articles in Electric Radio on the KL1/KS1. The Chippewa ran class AB1 while the T'bolt ran AB2 I believe. The T'bolt suffered from having too low a plate voltage. I have used a T'bolt at work, for some testing, as it can tune anywhere in HF band. It struggled to supply 650 watts of output.

I hope to use a KL1/KS1 instead of my much lighter-duty SB220, to amplify low level AM from my exciter (TR7 in AM). For one thing, the plate transformer in the SB220 drives a doubler, and is really rated only for intermittent service. The KS1 plate iron is big Basler stuff, looks to be potted.

This appears to be the quickest way for me to get a decently strong AM signal on the air at present. 

John
K5PRO

Hi John,

Wow another KL1+KS1 mating!  Sounds like our amps were modified in a similar way as the screen regulation and clamp circuit in this one has been removed, along with the screen dropping resistors.  I agree with your comparison vs. the T-bolt...it's no lightweight but the iron in the KS1 is beefier. 

Yes there was a sheet metal cover on the KS1 bottom, should be no big deal to fab.  The cover for my final compartment is missing so I'll have some metalbending to do also.   You'll want to keep an eye peeled for a Weston model 1721 meter - that's the number that is printed on the dial scale and both meters are from that product series.   Back in the early 60's, Heath and Weston Instruments were sister divisions of  Daystrom Inc. which may well explain the connection.

73, Bob W9RAN

No you won't, I just came across this panel along with the bottom chassis panel.  I'll get them off to you soon but not quite sure yet as I am strapped for cash until payday on the 3rd.  However, I will finally be getting the manuals from Gary into the mail tomorrow.. sorry for the delay, been crazy around here with the holidays.
 
- JT

I've never found a published modification showing this conversion of the clamp tube and screen PS. I would have been perfectly content to have the screen dropping resistors and the string of VR tubes to maintain the correct screen voltage for AB1 or class C in mine. I suppose those resistors did add a lot of heat to the package though. With a separate screen power supply, one has to be very careful that the screen can only be energized with or after the plate voltage comes up on those 4-400As. Otherwise quick tube failure results. That includes the inevitable possibility that the HV lead comes loose (yikes!) or the fuses blow on the big power supply. One method which used in commercial amplifiers was to have a high impedance relay at the bottom of the HV meter multiplier resistors. This would pick up when the plate voltage reaches some minimum, say 1.5 kV in this amplifier. Then the screen power supply is enabled.

Since i never got a schematic with my Chippewa of the mods that someone applied, I dunno if this was ever done. It may be as simple as a relay that clicks on after the HV switch from the plate supply. That's the way i did it in my own modified DX100 where I regulated the modulator screen (EL34) voltage and got rid of the horrible center tap on the bleeder resistors in the HV supply. Loosing a pair of EL34s is a lot less painful than a pair of 4-400s though.