[Elecraft] KE: issue with installation of K3EXREF interface

Sat Apr 2 19:33:02 EDT 2016

Don, in this case the lock washer would jam into the opening for the
connector. If you look at the setup in the manual you'll see that panel hole
is oversized and the engineers put an o-ring on the connector that centers
it in the hole. The inside surface of the panel is masked to provide good
contact with a large flat washer that goes against the rear panel opening
and provides a good surface for the nut and lock washer that secures the
connector to bear against. 

The connector has a hex cut on the inside ferrule. Tightening is done with a
wrench or pliers on the nut outside while holding the hex cut ferrule on the
inside to keep it from turning. 

73, Ron AC7AC

-----Original Message-----
From: Don Wilhelm [mailto:w3fpr at embarqmail.com] 
Sent: Saturday, April 2, 2016 4:07 PM
To: Ron D'Eau Claire; 'Mike Cox'; elecraft at mailman.qth.net
Subject: Re: [Elecraft] KE: issue with installation of K3EXREF interface

One "trick" that I have adopted when tightening chassis mount BNC and SMA
female connectors is to put a mating connector on the outside of the
connector.  That mating connector can be held tightly with pliers or a
wrench without damage to the female connector that you are trying to
tighten, and you can secure the nut with a wrench.  The mating connector may
or may not have coax connected to it - that makes no difference.

The other thing that is often shown in manuals which is IMHO incorrect is
that the star washer should go between the grounding lug and the chassis so
the teeth of the star washer bite tightly into the metal of the chassis as
well as into the grounding lug - assuring a good ground path.
Another plus for the latter star washer positioning is that once the star
washer begins to 'bite', the grounding lug is not apt to turn as you secure
the nut.

73,
Don W3FPR

On 4/2/2016 6:52 PM, Ron D'Eau Claire wrote:
> Were you only holding the nut while tightening and the ferrule cracked?
>
> That is the first case I've heard of in the 5 years the K3EXREF option 
> has been shipped so it's possible there's an issue with some units, 
> especially since there are two cases.
>
> I'm curious because we might need to alter the procedure in the manual 
> a bit if it's something happening during installation.
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of 
> Mike Cox
> Sent: Saturday, April 2, 2016 2:59 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] KE: issue with installation of K3EXREF 
> interface
>
> Mine broke off too. It appeared for be a crimped ferrule but it split 
> and fell off as though it were already fractured. I carefully soldered 
> the coax braid to the connector to maintain the electrical connection. 
> I was careful not to overheat and melt the dielectric of the coax 
> which could have shorted the center conductor to the shell. It's working
well!
>
> Mike, AB9V
>
> On 4/2/2016 16:16 PM, Jim Spears wrote:
>> While installing the K3EXREF SMA-TMP cable, I ran into an interesting 
>> issue which I do not yet know if it is a problem or just interesting.
>>
>>    
>>
>> There is a ferrule or something similar over the cable where it 
>> attaches to the SMA fitting that is installed on the back panel.
>> while tightening the hex nut down, I must have torqued something as 
>> the ferrule broke into two pieces and fell off.  I finished off the 
>> installation and verified that the GPSDO does provide a suitable 10 
>> MHz
> signal into the radio.
>>    
>>
>> So the question becomes:  is this interesting or a problem?   I took a
> close
>> look and the problem might be improper grounding of the shield to the 
>> chassis at the SMA connector end.
>>
>>    
>>
>> If it is deemed to be a potential problem, I can request a new cable 
>> from support.  It will not take long to replace the cable.
>>
>>    
>>
>> Jim/N1NK
>>
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