Digging out the data sheets from that maker, it shows pots with 1/4"
shaft and 3/8" bushing, choice of two bushing lengths. That's on the
data sheet offered by Maplin. Digging deeper the factory data sheet
shows a reverse log pot can be had. http://www.omeg.co.uk/p20data1.htm
Whether in quantity one I don't know.
However if the pins don't match the board anyway, it might be handier to
go with a smaller diameter pot and wire leads. I've not checked those.
I don't think I've see a reverse log taper pot offered lately in US
catalogs that I've wandered through like Mouser. Allied doesn't offer a
dual pot of any value. But then Allied has never recovered from being
owned by Radio Shack. Newark neglects to show mounting and shaft
dimensions on line. Useless.
73, Jerry, K0CQ
On 2/10/2011 2:17 AM, Steve Hunt wrote:
Charles,
Thanks for the suggestions. I see a couple of problems:
* The pot mounts directly to the PCB, so swapping the ends means cutting
tracks which I'd prefer not to do at this stage. Of course if I modified
it for panel-mounting then it would be easy.
* The front panel is marked with an "Out" position with the knob fully
CW; in that position the AF frequency of the notch is above the filter
passband. Reversing the "sense" would mean that in the "Out" position
the notch is still within the passband, albeit at the LF end and maybe
not too noticeable.
All of this makes me wonder why TT went to the trouble of using a
reverse log pot. It would have been as easy - and arguably more logical
- to have the control work the other way round: i.e. the "Out" position
full CCW.
73,
Steve G3TXQ
On 09/02/2011 22:49, Charles P. Steinmetz wrote:
Steve wrote:
I can't think of any simple way of "fudging it".
You can swap the "end" contacts of the pot (i.e., cross the wires
that connect them to the PC card). This will restore the original
linearity, at the expense of lower frequencies being clockwise and
higher frequencies being counterclockwise with the knob.
Best regards,
Charles
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