Re: Another mod to the Bayou Jumper


random.path
 

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


Join main@4SQRP.groups.io to automatically receive all group messages.