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Author Topic: TenTec 238C tuner repair...  (Read 168 times)

KT0DD

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TenTec 238C tuner repair...
« on: July 04, 2022, 06:30:17 AM »

Now that Dishtronix has effectively buried the Ten Tec name 6 feet under with their repair shop shutting down, I have a TT 238C L network tuner to repair. The electronics and main parts are fine. However, on the 11 position fixed capacitor switch, and the antenna switch, Ten Tec designed their own in house switch position locking mechanism on the 238C. It's not the usual ball and slot type lock. This one only controls the shaft position in the front of the tuner. The ceramic / switching part is at the other end of the shaft. There is a cog like switch lock / coupler with a spring loaded arm and a small roller on the end of the arm that moves up and over the tip of the cog and settles into the groove as you switch. Well, the locking shaft of the cogs is wearing big flat wear spots in the bottom grooves and it's getting hard to switch. Partly my fault fore not lubing the cogs, but also I believe too much spring tension is on the roller, mashing the metal flat, and or the wrong strength of materials were used.

Anyway, are there any small machine shops in the Amateur world that could "Copy" 2 of these cogs if I send them in? If I can't get replacement cogs, I will talk to Palstar about modifying the inside front plate, removing the old mechanism and finding a typical ball and socket rotary assembly, although this could be hard. If anyone needs a visual picture, I'm sure a google search could find it. Constructive replies are appreciated as always.

Todd - KT0DD
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K5XS

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Re: TenTec 238C tuner repair...
« Reply #1 on: July 04, 2022, 07:32:03 AM »

Todd,

Have you considered a local machine shop?

Bernie
K5XS
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KT0DD

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Re: TenTec 238C tuner repair...
« Reply #2 on: July 04, 2022, 07:48:21 AM »

We have them here in my town, but most are geared for large industrial or oilfield and recreational things like boat props. I'll call one I know about and see, but I'm not expecting anything. Maybe they can refer me somewhere.
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N8YX

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Re: TenTec 238C tuner repair...
« Reply #3 on: July 04, 2022, 12:12:08 PM »

Are these metal or plastic pieces?

If the latter, there are a few 3D printer owners who are reproducing various gears and sprockets for things like the Tempo 2020 and Kenwood 530/830.

I've used a couple of online laser cutting services for 2D parts. If you have access to a CAD program, you might try laying out the flat part of the stopper and saving it to a file format that's compatible with one of them. There are similar services that can fabricate the attachment bushing. I'd probably design the "wheel" with a few holes for screws to secure the shaft bushing to it and have the bushing drilled and tapped for 2-56 fasteners.

A link to a high-res pic of the part you need would help.

ETA:

I found a couple pics of the inside of one (including the "wheels") but the angle and resolution of the photos don't give all the details I'd need to reproduce the required part.
« Last Edit: July 04, 2022, 12:17:02 PM by N8YX »
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KT0DD

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Re: TenTec 238C tuner repair...
« Reply #4 on: July 06, 2022, 07:17:30 AM »

Are these metal or plastic pieces?

If the latter, there are a few 3D printer owners who are reproducing various gears and sprockets for things like the Tempo 2020 and Kenwood 530/830.

I've used a couple of online laser cutting services for 2D parts. If you have access to a CAD program, you might try laying out the flat part of the stopper and saving it to a file format that's compatible with one of them. There are similar services that can fabricate the attachment bushing. I'd probably design the "wheel" with a few holes for screws to secure the shaft bushing to it and have the bushing drilled and tapped for 2-56 fasteners.

A link to a high-res pic of the part you need would help.

ETA:

I found a couple pics of the inside of one (including the "wheels") but the angle and resolution of the photos don't give all the details I'd need to reproduce the required part.

They are metal, probably aluminum the way they are flaring. Local Machine shop that can do it is  booked 6-8 mos. out. 73,
Todd-KT0DD
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KT0DD

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Re: TenTec 238C tuner repair...
« Reply #5 on: July 06, 2022, 07:23:04 AM »

Todd,

Have you considered a local machine shop?

Bernie
K5XS

Local shops that can do this are booked out 6-8 mos. 73,

Todd
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KT0DD

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  • Posts: 568
Re: TenTec 238C tuner repair...
« Reply #6 on: July 06, 2022, 07:49:04 AM »

Are these metal or plastic pieces?

If the latter, there are a few 3D printer owners who are reproducing various gears and sprockets for things like the Tempo 2020 and Kenwood 530/830.

I've used a couple of online laser cutting services for 2D parts. If you have access to a CAD program, you might try laying out the flat part of the stopper and saving it to a file format that's compatible with one of them. There are similar services that can fabricate the attachment bushing. I'd probably design the "wheel" with a few holes for screws to secure the shaft bushing to it and have the bushing drilled and tapped for 2-56 fasteners.

A link to a high-res pic of the part you need would help.

ETA:

I found a couple pics of the inside of one (including the "wheels") but the angle and resolution of the photos don't give all the details I'd need to reproduce the required part.

They are metal, probably aluminum the way they are flaring. Local Machine shop that can do it is  booked 6-8 mos. out. 73,
Todd-KT0DD


Yep, no good photos online. I'm going to pull one of the cogs in the next few days and get good photos and measurements. Recently had right shoulder rotator cuff repair so it will have to be one of my good days where the bicep muscles aren't cramping up. I'll keep you posted. Thanks.

Todd
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W1VT

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Re: TenTec 238C tuner repair...
« Reply #7 on: July 06, 2022, 11:50:20 AM »

Is there a nearby makerspace?  There is one in Hartford CT.
https://makerspacect.com/metal/

I did a lot of machining not long after I had a stroke.  While my balance and coordination were impaired, I still had enough to turn the wheels on a miniature lathe and milling machine.  These days my balance and coordination are vastly better, so I've been golfing and gardening instead.  The small tools I used lacked the horsepower to do serious damage if I made a mistake.

Zak W1VT

« Last Edit: July 06, 2022, 11:54:29 AM by W1VT »
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