[Elecraft] 40m relay in K2 LPF stage - sorry if this is blank

[Jim Giercyk]

Sorry, of course I mean that the continuity tester reads 0 ohms, not 0 volts.  That's embarrassing.  :o


--- jim at giercyk.com wrote:

From: "Jim Giercyk" <jim at giercyk.com>
To: <don at w3fpr.com>
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] 40m relay in K2 LPF stage - sorry if this is blank
Date: Mon, 2 Mar 2009 16:40:14 -0800


Thanks Don,

You're right, my email was a little ambiguous. I am using the 'Continuity' tester on my DVM to get a relative (between relays) idea of what I should see.  As you pointed out, it's difficult to make accurate resistance readings across relays.  The continuity tester has a fixed tolerance for resistance, and if it reads 0v +/-[tolerance] it beeps indicating that the points the probes are touching within the same circuit and that there is no resistance between them.

Given the above, positive means I get a beep (same circuit, no resistance) and and negative means no result (resistance between points > 0 +/-tolerance).  This is a crude way of testing, but it gives me an indication of what I should be seeing with respect to the other relays in the stage.  The 'beep' is a benchmark for low/high, and is a constant value.  Believe me, I've never been mistaken for an engineer  ;)

So all that being said, I get a  beep on pins 3 and 8 on every other relay, but the 40 meter does not beep.  It's an inconsistency that I can't explain, and so I will defer to minds greater than my own.  Help!   :)

Thanks for all of your help,

Jim  

   

--- w3fpr at embarqmail.com wrote:

From: Don Wilhelm <w3fpr at embarqmail.com>
To: jim at giercyk.com
CC: Elecraft reflector <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] 40m relay in K2 LPF stage - sorry if this is blank
Date: Mon, 02 Mar 2009 14:56:49 -0500

Jim,

I don't understand your terminology.  In most common usage, positive and 
negative have nothing that relates to continuity - a continuity 
measurement is usually expressed as an amount of resistance (usually 
low) between two points.  Alternately, the conductivity can be expressed 
in mhos, the inverse of resistance, but that is not normally used except 
in engineering.

As for making relay measurements in the Low Pass Filter area, every 
point will have a very low DC resistance to ground because T4 lead 3 is 
permanently connected to the LPF and the other lead of that winding 
(lead 4) is connected to ground.  One must lift either lead 3 or 4 of T4 
in order to make meaningful resistance or continuity measurements in the 
LPF.

73,
Don W3FPR

Jim Giercyk wrote:
> All,
>  
> I seem to have lost receive on 40m on my K2 (rev A, no 60m), and I am thinking that I have a bad relay in the LPF stage.  I'm seeing some strange readings and wanted to get a consensus before attempting to remove a relay.  So, here is what I see:
>  
> With power off, measuring for continuity with W1, pins 3, 7 and 8 on the relay are negative.  However, pins 2, 4 and 9 are positive.  That makes no sense.  With the power off, shouldn't 3 and 8 be positive?  Time for a new relay??
>  
> Thanks,
>  
> Jim 
>   
>


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