[Elecraft] K3 Broken AF knob and bad serviceto geta replacement.
Paul Christensen
w9ac at arrl.net
Thu Dec 3 12:08:35 EST 2009
Also, if the electrical AF/RF knob swap is done, the slightly longer inner
knob on the Sub AF control makes its use as a fader between Main AF and Sub
AF a dream to use. Details below.
Paul, W9AC
> BTW, the mod is likely possible with a future F/W change to allow changes
> just as the current menu allows for 'Normal" and 'Balance' audio
> functions.
> If that ever happens, the wiring mod is very easily reversible in less
> than
> a minute with no evidence left behind.
>
> Paul, W9AC
>
> ----- Original Message -----
> From: "Paul Christensen" <w9ac at arrl.net>
> To: <elecraft at mailman.qth.net>
> Sent: Thursday, September 10, 2009 12:27 PM
> Subject: [Elecraft] K3 AF/RF Mod
>
>
>> Okay, I couldn't leave well enough alone...
>>
>> Yesterday morning, I was working a T30 station split on 40m with the K3's
>> Sub Rx and became a bit unnerved with the manipulation of the K3's "Sub
>> AF"
>> control when balancing between Main and Sub receivers. Multiple quick
>> reaches for the "balance" function on the upper Sub AF control's outer
>> ring
>> was causing me to accidentally come in contact with the other controls.
>> Looking at the K3 schematic, all four controls (Main AF, Sub AF, Main RF,
>> and Sub RF) are all 10K in value. Even when the K3's AF control function
>> menu is selected for "Normal," rather than AF "Balance," a similar issue
>> can
>> arise when trying to quickly balance the Main/Sub AF controls on one
>> shaft.
>>
>> I removed the front panel to inspect the Front Panel PCB and thought a
>> swap
>> of the Sub AF and Main RF controls could be easily accomplished. Here's
>> a
>> "before" photo of the PCB area:
>>
>> http://72.52.250.47/images/K3-AF-1.jpg
>>
>> And the "after" wiring...
>>
>> http://72.52.250.47/images/K3-AF-2.jpg
>>
>> A hot glue gun can be used near the 5-pin header to keep the two ribbon
>> cables from interfering with future front panel extractions and
>> insertions.
>> Now, the upper controls handles Main AF (inner) + Main RF/SQL (outer).
>> The
>> lower controls handle Sub AF/Balance (inner) and Sub RF (outer).
>>
>> When I engage split operations and use the Sub Rx, manipulating the
>> balance
>> between Main AF and Sub RF is easier with a bit less propensity to
>> accidentally come in contact with the adjacent controls since: (1) the
>> Main/Sub AF balance function is now on the inner concentric control and
>> extends out further from the front panel than the outer concentric ring;
>> and
>> (2) the balance function is now moved to the bottom where the hand can
>> approach the control from the bottom rather than directly in-line with
>> the
>> knob.
>>
>> If needed later for a sale, reversal of the mod is very easy. Certainly,
>> this mod is not for everyone. However, I would think that in later PCB
>> revisions, Elecraft could provide the option of selecting the existing
>> format or the modified format at the time of purchase -- or to the
>> builder
>> who simply makes a few header pin changes during construction.
>>
>> Of course, the front panel legends also need changing and that's probably
>> the biggest drawback to the mod. In my case, I will use new legends
>> printed
>> from a Brother 'P-Touch' printer -- printed with white lettering against
>> black background tape. Font size and type is adjustable to match the
>> existing legends on the K3.
>>
>> Paul, W9AC
>>
>>
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