BNC connector oddity on KX3

[rich hurd WC3T]

The denouement to the story:  I wrote to Elecraft and purchased P/N
E850552, the KX3 Antenna Connector Assembly w/LPF.   It arrived today.

After the cub scout meeting tonight (my son went from Webelos to the local
scout pack in the crossover ceremony tonight) I spent the last 20 minutes
(and two slices of pizza) putting it in and swearing at not being able to
line up the pins in the ATU in the KX3 radio.  After several fits and
starts, I attached the BNC and tuned immediately to 1:1 on 40 and 20
meters.    Best $50 or so that I ever spent.

Sometimes ya just gotta go for the gusto.   Now to hook everything else
back up from the trip to the mountain, and get on the air again!

On Fri, Mar 9, 2018 at 6:04 PM, rich hurd WC3T <[hidden email]> wrote:

> Thanks Don; I remember that we went over this earlier in the thread.
>
> Highly unlikely that I had legacy stuff as I became a ham in 2015 and
> acquired most of my stuff new.
>
> I am inclined to think that it was more possibly an out of spec 50 ohm
> connector or a manufacturing defect.  I've already worked on the finger
> bending thing but I ageee that given my lack of success that I'd be best
> served by spending the $47 and just buying a new assembly and replacing it.
>
>
> I appreciate all the help and suggestions from all the Elecraft community.
>
>
> On Fri, Mar 9, 2018 at 17:48 Don Wilhelm <[hidden email]> wrote:
>
>> Rich,
>>
>> Since you have traced the problem to the contact between the female BNC
>> and the male (yes your twisting and applying pressure confirms that is
>> the problem).
>>
>> It is entirely possible that if you had some old cables made with old 75
>> ohm BNC male connectors, that they could have enlarged the female pin
>> causing it to become marginal when used with the 50 ohm male connectors.
>>
>> You may have success with a very slender tool to bend the 'fingers' of
>> the female connector toward the center, but the best cure is to replace
>> that connector.
>>
>> Before we get into another long discussion of 50 ohm and 75 ohm center
>> pin diameters, let me say that modern BNCs use the same diameter center
>> pin for both.
>> That was not always true, so beware when buying older BNC jumpers at
>> hamfest flea markets - the old ones could be old 75 ohm BNCs with the
>> larger center pin.  Those less than 10 or 15 years old are OK.
>> It may also be that *some* imported BNC connectors do not have the
>> proper diameter.  For best results, buy only Amphenol connectors or
>> other trusted brands.
>>
>> 73,
>> Don W3FPR
>>
>> On 3/9/2018 11:13 AM, rich hurd WC3T wrote:
>> > I've pretty much exhausted most of the permutations of my cables and
>> > connectors.  The only persistent behavior is that if I apply slight
>> > pressure to the side of the BNC connector where it plugs into the jack
>> on
>> > the KX3, or sometimes if I twist it and then apply slight pressure just
>> so,
>> > I see a jump in the noise floor and instead of the internal ATU wearing
>> > itself out and giving up with a 9:1 or 7:1 SWR, it immediately tunes to
>> 1.0
>> > or 1.1.   I have removed/swapped all my the antenna leads.  I have four
>> of
>> > them, all Cables On Demand (Amphenol) manufacture.  I also have a
>> number of
>> > BNC to banana plug jacks, and even an MFJ-1899T.  If I replace the leads
>> > without doing the twisting-and-slight-pressure thing, I lose the RF
>> > connection; the S meter has no indications on it, and the noise floor is
>> > nonexistent.
>> >
>>
> --
> 72,
> Rich Hurd / WC3T / DMR: 3142737
> PA Army MARS, Northampton County RACES, EPA-ARRL Public Information
> Officer for Scouting
> Latitude: 40.761621 Longitude: -75.288988  (40°45.68' N 75°17.33' W)
> Grid: *FN20is*
>
>

--
72,
Rich Hurd / WC3T / DMR: 3142737
PA Army MARS, Northampton County RACES, EPA-ARRL Public Information Officer
for Scouting
Latitude: 40.761621 Longitude: -75.288988  (40°45.68' N 75°17.33' W) Grid:
*FN20is*
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