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Dubis7

Keyboard Component - Substitute for RF Extender?

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15 hours ago, Dubis7 said:

Okay, I've been working this over and looking at how the cables are designed. Here's my current thoughts:

The extender would be made of five pieces. A female end, a male end, a male center pin with a flared ring in the middle, a plastic ring and a standard piece of coax cable with the outer insulation stripped off to reveal the dielectric mesh underneath. The central coax core would be stripped back on both ends, one of which would be wrapped around and soldered to the back end of the male center pin behind the ring. You can then pull it back into the male end until the pin was flush with the outer male bit and solder that down. Take the other end of the coax cable and run it through an open hole in the female end and apply solder to the side. The two metal pieces could even be designed with channels to lock into each other like a BNC connector. Then all you'd have to do is slip the plastic over the top and have it designed in a way that it snaps onto both sides of the metal connection between the male and female ends. A design like that would make it fairly easy to assemble by hand once you have the pieces. 

 

It looks like a block of stainless steel will be the best option for construction. Should match visibly and it'll make soldering easy. I figure if we get a prototype cut and tested this could either be available as a hand assemble kit or I could do the assembly for each. 

I think this might require a diagram to visualize it.

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8 hours ago, Lathe26 said:

I think this might require a diagram to visualize it.

Yeah I agree. Let me come back with some visuals. 

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I should mention that part of the shielding of the extender is exposed so that it make contact with the KC's own shielding.  The KC's shield has a hunk of metal that comes up to the KC's pass-through hole for the RF extender to make the connection.  It also constrains the diameter of the extender at this portion of the pass-through hole.  I'll include photos of all this so that it is clear.

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43 minutes ago, Lathe26 said:

I should mention that part of the shielding of the extender is exposed so that it make contact with the KC's own shielding.  The KC's shield has a hunk of metal that comes up to the KC's pass-through hole for the RF extender to make the connection.  It also constrains the diameter of the extender at this portion of the pass-through hole.  I'll include photos of all this so that it is clear.

That's why the male end of the adapter is so long, right? I've seen that metal bridge while working on my own unit, I figured that was an RF shield connection point. If we match the measurements of the original it should be a self-solving problem, just put metal where metal already is. 

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5 hours ago, BBWW said:

No, too short unfortunately, and that's looking for a screw on coax adapter. The Intellivision master component video out is the same female style plug they used for RCA connectors. 

 

I've had luck with stacking two adapters, though Lathe is right about them wanting to pull apart when you try to pull the whole thing out. Thankfully I have some long thin pliers that can reach in to grab the offending adapter but that's a temporary solution. I'm going to solder the two together, I think. That way I have something reliable while I'm working on this reproduction idea. 

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You could probably wrap them together tight with some electrical tape too.

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Here are the measurements for the KC's RF Extender.  Please note that they are all in inches, mainly because that is the only units my tools directly measure. 

 

1670489885_KCRFExtenderMeasurements-Length-wise.thumb.png.3216f525e09421f3eb7fa5ca4a8d04cf.png

 

2027750101_KCRFExtenderMeasurements-MaleEnd.thumb.png.608dc2eb747d50f5f9dd894152b354c7.png

 

245903233_KCRFExtenderMeasurements-FemaleEnd.thumb.png.306f220f09daf70ed5e2f15e29a88681.png

 

Here are photos of the KC's pass-thru hole that the RF Extender goes through.  The metal piece visible in the bottom portion of the pass-thru hole is part of the KC's internal electrical shielding.  This metal piece makes contact with the exposed metal of the RF Extender, which itself is connected the metal shielding of the Intellivision Master Component.

 

Outside view of the pass-thru hole:

2144377538_KCRFPassthrough-Outside.thumb.jpg.e436ada41eeb44eb7be1b715a06c7ff8.jpg

 

Inside view of the pass-thru hole (i.e. viewed from inside of the large recess the Intellivision Master Component goes into in the Keyboard Component):

1955238553_KCRFPassthrough-Inside(2).thumb.jpg.eaeed8f1b6ff748566a22e2567ed6d6d.jpg

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Here's the equipment used to take the measurements:

1. Calipers that measure down to 1/1000 of an inch.

2. A head magnifier to improve measurement accuracy.

 

20210807_210311.thumb.jpg.c41a0e56481c811926d0dfb0e26b1c4f.jpg

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Amazing. Thank you Lathe! I'm getting someone with actual drawing skills to sketch out the blueprint for how this thing can come together. Expect that in the next few days or so. If everyone says that's good I'll start contacting folks with resin print and CNC experience to build a prototype. 

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Quick timing update: The artist I'm working with is booked until this weekend. We're going to sit down together either Saturday or Sunday and get this sketched out.

 

Just don't want anyone to think I've forgotten. It's still happening. 

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Don't worry about minor delays of days or weeks.  It often takes years to just to find an RF Extender.  😉

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Okay! We have a design. I simplified my original pitch to something with 4 components and no soldering required. 

Part 1: An outer plastic ring with a recessed groove inside. 


Part 2: The outer metal collar. It visibly matches the outer metal part on the original adapter, and adds a raised groove around the center that the recessed groove on the outer plastic ring will snap into. The inside narrows slightly between the female opening and the groove just above it, then has a screw cut into the inside up to the groove that marks the beginning of the male side.


Part 3: An inner plastic cylinder that runs the length between the narrowing on the female side of the metal collar and the groove that marks the beginning of the male side on the metal collar. It has a screw cut into the outside that will tighten into the inside of the collar. It also has a hole cut into the center. The bottom of this hole narrows to match the standard width of male RF pins much like the design on the inside of the metal collar, then has a screw cut inside all the way to the top.


Part 4: An inner metal pin with a screw cut down much of the length to match the screw cut on the inside of the plastic cylinder. This pin narrows at the top to match the standard width of all male RF jacks.

 

Proposed assembly: The wider section of the inner metal pin screws into the center of the plastic cylinder. The wider section near the bottom prevents it from screwing beyond a certain point, leaving just enough length for an additional male RF cable to plug into it and contact the male pin running through the adapter. The plastic cylinder then screws into the metal collar, and the wider inside on the female end prevents it from screwing in too far. The plastic ring slides onto the top and snaps into the groove, locking it in place and matching the appearance of the original part.

 

What do you guys think? Any feedback so far? This could probably be done with one metal lathe, one resin printer and some aluminum. 

rfadapterforkeyboardcomponent.png

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The attention to detail for what is arguably one of the most obscure parts for the Intellivision is fantastic!  I don't have anything useful to add, other than to suggest that since this part will be largely invisible once installed, you don't need to obsess over the details TOO much.  Functionality is more important.

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3 hours ago, retrogmr said:

The attention to detail for what is arguably one of the most obscure parts for the Intellivision is fantastic!  I don't have anything useful to add, other than to suggest that since this part will be largely invisible once installed, you don't need to obsess over the details TOO much.  Functionality is more important.

Thank you! My girlfriend (the artist) says thanks too, she's also a huge enthusiast.

 

My only point of uncertainty with this design is whether the center pin contact will be enough to sustain a stable electrical connection. I think the answer is yes if we get the distances right, but I'm not sure if they had another way of doing it at the time. Guess we'll find out.

 

I'm currently seeking someone with a metal lathe to move this to the next step. I've got plenty of resin print connections as is. More to come. 

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So a quick update, and sort of a call for assistance if anyone is familiar with CAD. In hunting for lathing services I came across this website. I'm going to do a little more research on the subject, but it looks like we could design the pieces in CAD, then have them manufactured by this service. Might save money over getting someone to turn the metal by hand. 

 

Barring that, I'm waiting to hear back from a few emails to machinists. I'll let you all know as soon as I have anything to report.

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Just wanted to update everyone on the status of this:

I'm working with a CAD designer to get the hand drawings turned into something that can be produced physically. From there it looks like I've got someone with a lathe lined up to cut the metal parts. I'm going to speak with him about the two plastic bits, but with the CAD designs it shouldn't be any issue to either have him do all four parts or have someone resin print the plastic bits and ship them to him to cut the screws into. 

 

Should have more news in the next week or so, hopefully a prototype lined up not too long after that. 

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