[Elecraft] [K3] RE: K3: Relay noise?

Thu Dec 10 05:53:26 EST 2009

I recently ran into a similar issue when interfacing an Ameitron QSK-5, K3, 
and SPE 1K amplifier.  Regardless of power through the QSK-5, it produces an 
audible "tick" when keying.  Yes, there are two relays inside the QSK-5 
unit, but neither is the cause.

It turns out that the QSK-5's PIN diodes are being biased with moderately 
high voltage. The ticking sound follows the application of diode bias.  I 
could swear it was the input signaling relay when I tried to localize the 
sound.  Only, the PCB is functioning as an acoustical sound board (akin to a 
piano or violin), amplifying the "tick" produced by the biasing of the PIN 
diodes.   I still don't know the exact ticking mechanism.

I've heard similar effects when using high-voltage transistors.  Anyone who 
has worked extensively with these transistors or high-power PIN diodes care 
to add an explanation?

Paul, W9AC

----- Original Message ----- 
From: "AC7JW" <jreber at thebluezone.net>
To: <elecraft at mailman.qth.net>
Sent: Thursday, December 10, 2009 12:40 AM
Subject: [Elecraft] [K3] RE: K3: Relay noise?

>
> Thanks Steve.
>
> It's sure strange that I get the same click whether I run 1 W, or 100 W. 
> I
> could understand some sort of residual magnetic effect (for lack of a 
> better
> term) causing some mechanical movement to create the noise if it was only
> present while running high power, in which case high currents are present,
> and thus the potential for a powerful magnetic field. But at 1 watt- there
> is something else going on. In any case, I don't think it's a problem- 
> just
> an annoyance.
>
> Jason
>
>
>
> From: Steve Ellington [via Elecraft]
> [mailto:ml-node+4143590-665332999 at n2.nabble.com]
> Sent: Wednesday, December 09, 2009 8:57 PM
> To: AC7JW
> Subject: Re: K3: Relay noise?
>
>
>
> I used some plastic tubing stuck in one ear trying to track it down. I
> narrowed it down to one relay but it's been at least 6 months ago and I
> can't recall which one made the noise. I had suggestions to check for 
> loose
> ferrite chokes along the high current DC line but that wasn't the source. 
> If
>
> I happen to remember which relay it was, I'll post it here. 73
> Steve
> N4LQ
> [hidden email]
> <http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4143590&i=0>
> ----- Original Message ----- 
> From: "AC7JW" <[hidden email]
> <http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4143590&i=1> >
> To: <[hidden email]
> <http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4143590&i=2> >
> Sent: Wednesday, December 09, 2009 9:40 PM
> Subject: Re: [Elecraft] K3: Relay noise?
>
>
>>
>> I've followed this thread concerning a QSK clicking noise through all
>> comments, as well as other similar threads on the list, but it doesn't
>> appear as if anyone ever came to a firm conclusion as to origin of this
>> clicking noise. As others have stated, I can hear a very faint mechanical
>> clicking that follows my code when using QSK. It sounds like it's coming
>> from the KPA100 region, but I can't tell for sure.
>> Did anyone ever come to a conclusion, or receive any information from
>> Elecraft?
>>
>> Thanks-
>> Jason AC7JW
>>
>>
>> Steve Ellington wrote:
>>>
>>> Is there a mechanical relay that follows keying? I've had my K3 for
>>> nearly
>>> a
>>> year and didn't notice any relay noise until lately. I know the antenna
>>> TR
>>> is done by pin diodes but I can now hear the faint click of a small 
>>> relay
>
>>> that wasn't there before. I'm using ver. 2.8
>>> Steve Ellington
>>> [hidden email]
> <http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4143590&i=3>
>>>
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