Re: KX1 Please need help with T/R thump

Posted by Jerry W7ANM on May 26, 2011; 5:34pm
URL: http://elecraft.85.s1.nabble.com/KX1-Please-need-help-with-T-R-thump-tp6395259p6407957.html

Don,

I did extract the old Q7 without any damage or problems.

I was looking at the spec sheet for the 2N3904 after getting your last suggestion and after ordering the 2N4124 from Elecraft. Do you think the 2n3904 is a superior replacement for the 2n4124? Any reason to suspect it would not work or why the 2n4124 was chosen for that circuit?

73,
Jerry

On Wed, May 25, 2011 at 5:13 AM, Don Wilhelm-4 [via Elecraft] <[hidden email]> wrote:

  Jerry,

That voltage would indicate Q7 may be at fault.
If you do not have a proper replacement, but do have a 2N2222A or 2N3904
in stock try one of those as a test.

73,
Don W3FPR

On 5/24/2011 11:48 PM, Jerry W7ANM wrote:

> Thanks Don,
>
> Maybe were getting somewhere. Q7s base is at zero during receive but on
> transmit it only goes to 0.1v.
> The 6T_2 voltage on the other side of R28 goes from 0v during receive then
> to 5.63v on transmit. (Normal?)
>
> Looks like I will need to get another Q7?
>
>

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