[Elecraft] KX3 2m Install

Tue Apr 26 17:49:07 EDT 2016

Thanks Bruce: If that capacitor is no longer an issue we don’t want to be asking builders to look for it, Hi! 

I’ll look into the TO-220 issue. As long as it’s tightly clamped by the screw, it should provide good heat transfer to the case. 

73, Ron AC7AC

From: Bruce Nourish [mailto:w0mbt at w0mbt.net] 
Sent: Monday, April 25, 2016 8:55 PM
To: Ron D'Eau Claire; Elecraft Reflector
Subject: Re: [Elecraft] KX3 2m Install

Yes, sorry, C180, not C120. Not that I'm complaining, its absence made assembly easier.

Re: TO-220. If you look at Fig 24 (bottom of p28) in the instructions, you'll see TO-220 "leaning back" inwards from the side of the case, loosely held by the nylon screw. My TO-220 looked like that before I inserted the module -- so far so good. 

When I inserted the module, the transistor heat sink went into the gap between the top of TO-220 and the case. I wiggled it a bit until the hole in the heat sink, and the top hole of TO-220 approximately lined up. I was able to screw in the metal Phillips screw fine, so the heat sink should have a good connection to the case. But TO-220 was still "leaning back", meaning that the bottom hole of TO-220 was still at an angle. I tried unscrewing both screws, but the heatsink had wedged TO-220 firmly at that angle.

Bruce

On Mon, Apr 25, 2016 at 8:17 PM Ron D'Eau Claire <ron at cobi.biz> wrote:

Hi Bruce:

Are talking about C180 near J4? I'll check into it. It won't be the first
time the engineers made a change and didn't realize it impacted the assembly
instructions (I'm 600 miles from Watsonville, but only milliseconds by voice
and e-mail. Still that can be "light years" at times, Hi!)

I'm not sure what could put the TO-220 screw at an angle. The TO-220 heat
sink simply slips in between the retainer, which is then pulled tightly
against the TO-220 heat sink and the side of the case. That's the critical
part - good mechanical and thermal contact between the TO-220 heat sink and
the side of the case.

Have you tried loosening both screws and then re-tightening them? What comes
to mind is that in tightening the top screw, the retainer might have turned
slightly, misaligning the bottom screw in the hole. With everything in
place. Loosen both screws a bit, then retighten the bottom (nylon) screw to
hold the retainer, then tighten the top screw and see if things line up
better.

I'd appreciate hearing if that works either at my address on this message or
ron at elecraft.com.

73. Ron AC7AC

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bruce
Nourish
Sent: Monday, April 25, 2016 5:37 PM
To: Elecraft Reflector
Subject: [Elecraft] KX3 2m Install

Hi folks,

Last night I installed and configured a KX3 2m module following the current
instructions on the website (Rev C). My KX3 is a recent factory build.
Everything seems to be working fine; I haven't actually tried it on-air yet
(need to finish my 2m Moxon), but at least I didn't blow my rig up.

I encountered one difference with the instructions: When installing the LO
coax on J4, I could not find any capacitor C120 to avoid. My KX3 simply
doesn't have C120 or R81 on that PCB. Has something changed in recent KX3s?

The only hard part was the final installation, specifically clamping the
heatsink lug properly with retainer TO-220. It seems like the clamping
arrangement unavoidably puts the nylon bottom screw at a weird angle. I
double-checked the orientation of TO-220 and redid these steps over several
times, and couldn't figure out any other way to make it work. Is this right?
If so, a clarification in the instructions would help.

Bruce
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