[Elecraft] K3 - MH2 mic switch mechanical noise

[Richard Fjeld]

Bill,

Be careful with silicone.  Back in the 70's, give or take, it was discovered 
in a lab that silicone widely creeps and gets into electrical contacts and 
can cause circuit failures.  The source was good. I won't let it in my 
house.

I have read that WD-40 does NOT contain silicone, but I don't know if that 
source was reliable.
Some petroleum jelly w/o additives ought to be safe.

A micro-switch works well, but it 'clicks'.   If the PTT contacts are like 
other mics, you need a lever to actuate the contacts.  Plastic PTT 
lever/buttons are rigid.  Something flexible like rubber, or vinyl tubing 
could be devised perhaps.  Maybe something like a soft ear-plug moving 
through a lubricated tube as a crude example.  As I have said, I haven't 
seen the MH2. If you saved the original parts, you could experiment w/o 
ruining the mic.

I just wanted to caution you about the silicone warnings. It could lead to 
big problems.

Rich, n0ce

----- Original Message ----- 
From: "Bill" <bill at w2blc.net>
To: "Richard Fjeld" <rpfjeld at embarqmail.com>
Sent: Monday, November 12, 2012 6:12 PM
Subject: Re: [Elecraft] K3 - MH2 mic switch mechanical noise


> Thanks Rich for the kind reply. I am looking at ways to re-engineer the 
> MH2. Basically, it involves a very cheap switch and plastic sliding on 
> plastic. Two distinct problems.
>
> I am working on using bubble switches as replacements and have tried a 
> silicone lubricant.
>
> I expect the combo of both tactics will relieve the problem.
>
> Thanks again,
>
> Bill W2BLC
>
>
>
> On 11/12/2012 6:18 PM, Richard Fjeld wrote:
>> Bill,  you said in part:
>>
>>> It is a mechanical problem within the mic, as other mics do not do this.
>>
>> You are partially right.  The word is *SOME*  mics do not do this.  I 
>> have had both hand-mics and desk-mics do it.  AND, it was not only a 
>> spike; it was during transmit if I changed the pressure on the PTT.  The 
>> buttons should be soft material.   Yes, it is annoying.  It is one of the 
>> reasons I went to a boom-mic (CM500). No way for a mechanical noise 
>> pickup from a detached PTT.
>>
>> Now, it is so quiet I get complaints that my rag-chew group can't tell 
>> when I release the PTT.  (Longevity affects the hearing.)  I wrote in 
>> awhile back at their request to see if the K3 could do a short 'dit' when 
>> I released the PTT. (That opened up a can of worms)
>>
>> I don't know what the innards of the MH2 looks like, but you may try to 
>> improve what the element is cushioned in to reduce the microphonics. If 
>> it is audible noise, the electret element will 'hear' it.
>>
>> Rich, n0ce
>>
>>
>> ----- Original Message ----- From: "Bill" <bill at w2blc.net>
>> To: <elecraft at mailman.qth.net>
>> Sent: Saturday, November 10, 2012 9:55 AM
>> Subject: [Elecraft] K3 - MH2 mic switch mechanical noise
>>
>>
>