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 Post subject: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Sun 22, 2020 6:20 pm 
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Location: West Point, PA 19486
I wasn't sure where to post this, so it's in the Clubhouse.

This guy is going to "re-kit" a KT-135.
https://www.youtube.com/watch?v=pT9CJdm ... e=youtu.be


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Sun 22, 2020 6:50 pm 
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Location: Carmel, Indiana
So what's he going to do with it after it's been reduced to pieces, relive the old kit building glory days by building it back up again?

Quote:
We are going to show a 'real, live' working radio get turned back into a kit, so we can build it up better.

Sounds more like a full restoration to me. Shoot, I do that all the time when I restore 1920s superhets, tear them down to the nuts and bolts, clean and polish everything, and then build them back up again. That's also how I restored my Scotts, Lincolns, and McMurdo Silvers.

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Last edited by Indiana Radios on Nov Sun 22, 2020 7:02 pm, edited 1 time in total.

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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Sun 22, 2020 6:58 pm 
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Indiana Radios wrote:
So what's he going to do with it after it's been reduced to pieces, relive the old kit building glory days by building it back up again?


Yes, exactly.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Sun 22, 2020 7:57 pm 
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Indiana Radios wrote:
Shoot, I do that all the time when I restore 1920s superhets, tear them down to the nuts and bolts, clean and polish everything, and then build them back up again.


Hah, there is a lot more to that than what Dave is going to do. There are only three tubes in a KT-135. No IF cans, not even a dial string or pilot light.

My reason for the post may not be clear. We can watch people like BUZZ1151 tear down a radio or even build one up from scratch. In this case, I'm interested in the KT-135, and felt some of the guys here who like regens would also be interested.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Sun 22, 2020 9:46 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Colorado Springs, CO
My first general coverage receiver that I used as a novice ham was the Lafayette KT-200 which was a kit radio. To upgrade to a better receiver, I had to trade it in on an HQ-100. I often wished I had the KT-200. I found one a couple of years ago on ebay for a good price and it need quite a bit of restoration. I took it down to kit level and rebuilt it. Almost like getting the kit the first time.

http://radioremembered.org/kt-200.htm

Bill - K5MIL


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 4:31 am 
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Location: Peekskill, NY
"felt some of the guys here who like regens would also be interested."

That KT-135 was the first receiver I owned - it was purchased at the LRE store on Rt. 17 in Paramus, NJ. - and the cabinet (sold seperately)
was out of stock. My late brother helped me build it, and manufactured a cabinet out of fiberboard for me.

Very interested.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 2:46 pm 
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jim rozen wrote:
My late brother helped me build it, and manufactured a cabinet out of fiberboard for me.



Here's one in a cabinet made of some kind of particle board.
Attachment:
KT-135WoodCase1.jpg
KT-135WoodCase1.jpg [ 276.66 KiB | Viewed 687 times ]

Attachment:
KT-135WoodCase2.jpg
KT-135WoodCase2.jpg [ 243.97 KiB | Viewed 687 times ]


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 3:16 pm 
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Bill Harris wrote:
I took it down to kit level and rebuilt it. Almost like getting the kit the first time.

http://radioremembered.org/kt-200.htm

Bill - K5MIL


Wow, what a great job. I can't believe somebody made all those mods to it, to its detriment!
Here's a bigger picture of you, from the World Radio History site.


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K5MIL.jpg
K5MIL.jpg [ 133.76 KiB | Viewed 681 times ]
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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 8:25 pm 
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SkyKing wrote:
Wow, what a great job. I can't believe somebody made all those mods to it, to its detriment!
Here's a bigger picture of you, from the World Radio History site.


The microphone in the picture is a cheap crystal mic I picked up somewhere and the stand is the filter holder out of a percolator coffee pot.

Attachment:
coffeePot.jpeg
coffeePot.jpeg [ 20.34 KiB | Viewed 651 times ]


Bill - K5MIL


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 8:44 pm 
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Location: Moss Landing CA
It was working. It looked to me like the detector plate voltage and/or number or feedback turns was excessive.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 11:27 pm 
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Scota4570 wrote:
It was working. It looked to me like the detector plate voltage and/or number or feedback turns was excessive.

There was a 12AX7 in place of the 12AT7. He didn't notice till he pulled it out.
When I tried a 12AX7 in mine it was really detrimental to the operation of the radio. I sent him a 12AT7 in the mail.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Mon 23, 2020 11:55 pm 
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Joined: Jul Thu 16, 2020 8:44 pm
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That makes sense. Hi Mu triodes make poor regens. Lower mu run at low voltage always gave me the best result.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Tue 24, 2020 5:44 am 
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Bill Harris wrote:
SkyKing wrote:
Wow, what a great job. I can't believe somebody made all those mods to it, to its detriment!
Here's a bigger picture of you, from the World Radio History site.


The microphone in the picture is a cheap crystal mic I picked up somewhere and the stand is the filter holder out of a percolator coffee pot.

Attachment:
coffeePot.jpeg


Bill - K5MIL

The mike looks like an Argonne crystal lapel mike. That was my first mike and I still have it and it still works good. Lafayette sold them for $1.95.

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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Tue 24, 2020 8:46 am 
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Joined: Mar Tue 10, 2020 5:11 am
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Location: Mission Viejo, CA
Sheesh... doesn't he have any proper tools?? I winced in sympathy with those poor screws as he loosened em with that Swiss Army thingy... :shock: Then when he cut all the resistors and capacitors and coils loose... <shudder>....

SteveH


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Tue 24, 2020 9:08 am 
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Location: Tokyo
I did the same with a Knight Star Roamer, Space Spanner and Span Master. It's fun. And far cheaper than waiting for an unbuilt kit to show up on eBay. I rebuilt them in 'homebrew' order, that is, started with the PS, then the audio, etc, testing each stage as I went along, didn't use the assembly manual very much.

I also used an Argonne crystal mic back then, with a Hallicrafters HT-40. Excellent. Typical comment was 'you sound like a broadcast station', which, depending on the tone of voice, was sometimes a compliment, sometimes a criticism. But I didn't buy it at Lafayette, got it at Federated Electronics, Rte 22 Springfield, NJ. Had money burning a hole in my pocket that day, so I got the optional stand.

I clearly remember KN5MIL's photo in PE. I kept that issue for a long time because it had a review of the Mosley CM-1 receiver, which I wanted (and never got). I admit I suspected Bill was using that VFO instead of crystals.

If I were rebuilding a KT-135, I'd replace the 12AT7 with a 19EZ8. This tube has three 12AT7/6AB4 triodes in a 9 pin package. Use one as a grounded grid RF amp and replace that antenna coupling VC with an attenuator pot. All regens need a way to control RF level before the detector, and the GG amp with attenuator is perhaps the best.

Rob


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argonne.jpeg
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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Tue 24, 2020 6:59 pm 
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Location: Colorado Springs, CO
shinkuukan wrote:
I clearly remember KN5MIL's photo in PE. I kept that issue for a long time because it had a review of the Mosley CM-1 receiver, which I wanted (and never got).


I wished to own the Mosley CM-1 receiver but could not afford one at the time. I picked one up on eBay for a good price, restored it and I now use it on 40 meter AM.
http://radioremembered.org/mosleycm-1.html

Quote:
I admit I suspected Bill was using that VFO instead of crystals.

No way. I knew that if I even loaded the DX-60 to 1 watt over 75 watts input to the final, the limit for novice, the FCC would be knocking at my door so I certainly was not going to use that VFO until my general ticket arrived.

Bill - K5MIL


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Wed 25, 2020 1:23 am 
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Quote:
No way. I knew that if I even loaded the DX-60 to 1 watt over 75 watts input to the final, the limit for novice, the FCC would be knocking at my door so I certainly was not going to use that VFO until my general ticket arrived.


I thought the same way. I was sure the FCC had thousands of monitors constantly following each novice QSO, precisely and accurately measuring your frequency. And secret, high tech ways of measuring your input power at a distance. I operated on 40 meters only, but once I threw up an 80 meter bent and inverted V dipole and tried to make some contacts. Failed, but several days later I got a bunch of OO warnings from all over the US, including some from the west coast (I lived in NJ). My friends joked I was going to get the first OO WAS award. I was terrified I would come home from school and find several unmarked black cars parked in our driveway. As I walked in, FCC agents would wrestle me to the floor, handcuff me and take me into custody. 'And we're taking your beloved Vibraplex Original; you won't be needing this where you're going'.

Today I wonder if the FCC does any HF monitoring at all.

Rob


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Wed 25, 2020 3:29 pm 
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What is an 00 warning?


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Nov Wed 25, 2020 4:07 pm 
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Location: Montreal, Quebec
"Official Observer".

It was a program run by the ARRL to help keep the bands tidy. So people with the right equipment would watch the bands and if they noticed your CW was chirping or you were out if band, or transmitting harmonics, they'd send you an officisl postcard. I can't remember if it went beyond technical issues.

It was self-policing, and there was no way to enforce things. But if you didn't listen, the FCC might issue a ticket.

I notice the program is gone, I missed why, though something new is in place in the past year or so.

If you were starting out, especially if your transmitter was home made, you might not have the test equioment needed to fit the rules.


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 Post subject: Re: Tear down a Lafayette KT-135 live on YouTube
PostPosted: Jan Sat 02, 2021 3:18 am 
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Hi - this is my livestream series. Hope you enjoyed it.

The radio turned out nicely - if we weren't packing up for a move I'd throw up a nicer antenna to match the effort and lovely walnut case. In a segment I had to leave out due to background noise - this thing was doing very well at 160M CW during a contest - with enough fiddling I could get down to a couple stations in the moshpit and pick out who's who. But I am not deluded - its a really basic radio, the regen control is touchy on band A and is generally not smooth or consistant - and tuning anything narrow band take exceptional patience. But, it works!

It was a real thrill to experience putting together a kit from the 60's and I have respect for those who took these on with minimal experience and saw it out to the end. I know my 16 year old self would have rushed this in the excitement of 'exploring the air', then flubbed something along the way, and then done all sorts of damage trying to find out what was. Such a radio would be 50/50 success or in a cardboard box in the attic in embarrassment of my failure to build it right. And those who finished things like the HW-101 are now to me gods among men...and I've essentially done the same workup on one of those as well!

Another revelation was how able the free and open source tools like KiCad and FreeCAD are to doing this rapid prototyping, and that there are suppliers out there that can work to the price range of hobbyists. The replacement pointers from Ponoko, the polyvaricon PCB from OSHPark, the pointer spacers from my local STEM-oriented toy shop, and some other items - all were really easy to work with and get decently priced parts - I spent way more on the case and other parts.

A couple of last little issues remain. My original plan was to use countersunk screws to mount the polyvaricon to the PCB, which would have let me bring up the PCB closer to the sheetmetal. But flat countersunk screws at M2.6 and short enough were not cheap, so I had to pivot to mounting like I did. But, then the shaft adapter (from Mike's Electronic Parts) is now just a little short. Since I want to try out some 3D printed metal for these projects, I've designed a new shaft adapter that is longer, with all the features plus a recess for the mounting screw. Also, its going to bug me that those pointers are a little long. In time, I think I'll design new knobs and replace them outright.

We just packed up the workbench and everything in preparation to move but I'm looking to continue a regular streaming series for Sunday nights. So, we're going to try and find a compact project I can film anywhere. Any interest in seeing a 2 transistor TRF ala a 'Boy's Radio'? I'm thinking about replacing the existing circuit with something new. Another idea is to work up a replacement power supply for the Atwater Kent Model 40 that completely replaces the pitch-filled power pack.

Thanks to SkyKing for the assistance, parts and encouragement.


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