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Author Topic: N1ESE's Chippewa Thread  (Read 49972 times)
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N1ESE
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« Reply #75 on: November 14, 2007, 08:47:47 PM »

Just received an email from W9RAN.. the Chippewa arrived in fine shape today and he is very pleased to have her.
 
- JT
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W9RAN
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« Reply #76 on: November 20, 2007, 11:11:38 PM »

<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


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N3DRB The Derb
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« Reply #77 on: November 20, 2007, 11:15:22 PM »

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.
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WQ9E
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« Reply #78 on: November 20, 2007, 11:27:02 PM »

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
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Rodger WQ9E
Steve - WB3HUZ
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« Reply #79 on: November 21, 2007, 10:08:11 AM »

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



<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



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The Slab Bacon
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« Reply #80 on: November 21, 2007, 10:27:06 AM »

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.
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"No is not an answer and failure is not an option!"
John K5PRO
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« Reply #81 on: November 21, 2007, 11:27:32 PM »

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
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W9RAN
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« Reply #82 on: November 24, 2007, 11:59:58 PM »

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
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N1ESE
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« Reply #83 on: November 25, 2007, 06:35:03 AM »

The cover for my final compartment is missing so I'll have some metalbending to do also.
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
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John K5PRO
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« Reply #84 on: November 26, 2007, 11:08:21 AM »

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.
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