BJ question


David Wilcox
 

Has there been a change in the tuning pot or knob?  I am glad I didn't cut any of the shaft off because my knob snugs right down on the faceplate, and when I put it flush with the faceplate it becomes more stable in staying on frequency and easier to tune.  At first I had it about 1/16 inch above the faceplate to prevent scratching it but it works better down tighter.  Might put a piece of felt behind it like the knobs of yore.

Another question:  why does the attenuator pot work backwards?  I would think, clockwise = more attenuation.  Less attenuation at the 7:00 o'clock position.  Mine is least at the 5:00 o'clock and max at 7:00 o'clock. May have to fix that on mine.

Has anyone found a way to remove the lettering on the tuning pot? Then I could just use small press on numbers somehow relating to the frequency.  7  .03 .05 1.0 etc.  I think I could do it or if someone was good with Word or some printing program print out a ring that we could place on the knob skirt with dots or something we could make a chart for.

Dave K8WPE

On Feb 2, 2017, at 5:40 PM, CStratton groups@... [4sqrp] <4sqrp@...> wrote:

 

Thanks Jim and Larry -

I chose to cut the tabs and through hole leads flush with the bottom of the pot so it would sit lower on the board. I passed small pieces of bare wire up through the pcb holes for the three leads to solder to the remnants of the pot leads. This provided plenty of room for the S38 venier shaft to clear the pot frame.

Chip
AE5KA

On Tue, Jan 31, 2017 at 6:45 PM, Jim Sheldon <w0eb@...> wrote:
I used the normal standoffs, cut about 1/4 inch off the tuning pot shaft (maybe a little more) and inserted a couple washers under each standoff to adjust the height to the point that the vernier shaft would just work and still leave enough height on the other shafts to engage the setscrews on the knobs.

Jim 

On Jan 31, 2017, at 7:44 AM, CStratton <groups@...> wrote:

Hi Jim -

I'm trying the vernier dial mod to my BJ. To get an extra 1/8" of clearance for the shaft, I used 3/4" standoffs instead of the 5/8" standoffs. The work to let the vernier shaft just clear the pot, but now all of the other pot shafts are too short to be engaged by the supplied knobs.

Grinding the vernier shaft down would work, but to get 1/8" it looks like he set screw hole will be compromised.

What did you find on your build?

Thanks,
Chip
AE5KA

On Thu, Jan 5, 2017 at 7:49 PM, 'Jim Sheldon' w0eb@... [4sqrp] <4sqrp@...> wrote:
 

I had a 1.5" diameter Philmore vernier dial laying around so I decided to see how difficult it would be to install for tuning the Bayou Jumper which is sort of fast and difficult, but not impossible, to get just right. 
 
First, it was necessary to drill out the hole in the panel for the tuning pot to a diameter of 7/16" to allow for clearance of the shaft coupler on the vernier.  Next, it was necessary to cut the tuning pot shaft down to just over 1/4" long and the bottom of the shaft coupler still bottomed out on the frame of the pot, leaving the base of the vernier mechanism about 1/8" above the panel.  There are two options here, grind down the shaft coupler until the vernier sits flush with the panel and the coupler doesn't bind on the frame of the pot or use 1/8" or so of spacers between the panel mounting standoffs and the panel (easier at assembly time to add the spacers between the main PC board and the bottom of the standoffs).  The mounting holes for the vernier must be carefully laid out and drilled for 2-56 screws and 2 of these are used to mount it to the panel.
 
Before re-assembling the panel/pc board combination, set the shaft on the tuning pot to mid range and the vernier to midrange (#50).  Carefully fit everything into place, tighten all the panel mounting screws and other top side hardware just like you did on the initial assembly.  Next, very carefully tighten the set screw on the vernier's shaft coupler to lock it to the tuning shaft of the pot.  You will only have 180 degrees of rotation rather than the full 270 degrees but this should fall within the 7020 to 7130 range assuming you had done the calibration steps earlier.
 
I used the 1.5" Philmore S38 vernier.  The S50 is a 2" diameter dial and these are also available for somewhere around the same price or just a little more.  The S38 is the ideal one as it fits within all original markings on the Bayou Jumper's panel where the S50 will cover the word Tuning and the top will extend into, if not completely cover the original V shaped pointer at top center. 
 
It's a daunting modification and probably most won't do it, but it does really slow down the tuning and makes it much easier to tune in a CW station and it's now actually possible to also tune in the SSB stations at the high end if they fall within the tuning range.  The radio is quite stable and once tuned to a frequency I didn't observe any drift after a couple minutes of warm up.  Super job by the designers.
 
Jim - W0EB
 
 
It actually looks pretty decent mounted on the radio - helps a lot with ease of tuning in a signal.
 
 
Closer picture of the installed Philmore S38 vernier dial



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