[Elecraft] Ouch - An Update

[Matt VK2RQ]

I'd suggest to replace the toroid core, as the high temperatures to which it was subjected may have altered the characteristics of the material.

73,
Matt VK2RQ

> On 1 Jul 2014, at 12:40 pm, "Mike Lewis" <mlewis53 at gmail.com> wrote:
> 
> So brought the K3 in to work this morning to our lab area where we have
> static benches, blowers, wrist straps etc. and opened it up. Sure enough,
> the T4 transformer was pretty crispy looking. My boss who is also an avid
> ham (dream job setup :) ) then sprang into action. He removed the
> transformer, counted the turns, removed the old wire, found some new magnet
> wire of the proper gauge, rewound the toroid, and replaced both it and the
> straight through portion (which had gotten pretty hot from the proximity to
> the core.) Prior to stripping the burned turns off of T4 we looked at it
> under a microscope and saw that the windings had burned open in one place,
> effectively acting as a fuse of sorts. There didn't seem tpo be any other
> parts, connectors, or board traces that looked to have been stressed. I
> brought the radio home and hooked it up to a dummy load and a reasonably
> accurate external wattmeter. It seems to be fine, both on receive and
> transmit. 
> 
> 
> 
> I was hoping there was a built in SWR bridge cal procedure, but I didn't see
> anything like that in the manual. The SWR values reported though seem to
> match the LP-100A I am using externally pretty closely. I did try to follow
> the Wattmeter calibration and ran into some confusion on the procedure as
> written in the manual. I think I was able to puzzle it all out except for
> one item - how do you change the config menu item from CONFIG:WTMR LP to
> CONFIG:WTMR HP? It doesn't seem to change just by having the tune power
> changed to 50 watts, so I am at a loss on how to change it.
> 
> 
> 
> So perhaps my K3 is now alright again, although I would appreciate any other
> comments on other things to check or calibrate. And thanks to all on the
> list who helped me out. After this the next project is to fuse the DC supply
> cables to my DC blocks with some rationally small value of fast blow fuse :)
> 
> 
> 
> de Mike/KE0MF
> 
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