EMRFD Message Archive 13658

Message Date From Subject
13658 2017-03-05 13:12:37 RodWall1234@Gmail... Re: [emrfd] Disc Ceramic Capacitor "Adjustments"
Hi Bob,

When you.

 A bit of Sally Hansen Nail Hardener sealed the capacitor tops.

Did the capacitance change?

Regards,

Roderick Wall, vk3yc.

----- Reply message -----
13659 2017-03-05 15:27:01 bob_ledoux Re: Disc Ceramic Capacitor "Adjustments"
The 47pf I ground down to 42pf showed no change.  It was within a 0.1pf of the original value.

bob-N7SUR
13660 2017-03-05 15:47:15 Robert Fish Re: Disc Ceramic Capacitor "Adjustments"
Hi Bob,
What timing. I am building a 10Mhz filter this afternoon and I am struggling with getting the correct capacitances with values I have on hand.
I think i will try this method just for an experiment. If it doesn't work, I will just place the parts order that I was about to place anyway.

I presume your talking about through hole ceramic caps. If not, which side is the top and do you still have fingerprints? hi hi

Thanks,

Bob  K6GGO



 

The 47pf I ground down to 42pf showed no change.  It was within a 0.1pf of the original value.

bob-N7SUR


13661 2017-03-05 16:23:37 Dan Rae Re: Disc Ceramic Capacitor "Adjustments"
I have some commercial 10.7 MHz switched SSB / AM width crystal
filters. Curious to see how they'd done it I opened one up and the
width was altered with a bunch of NP0 disc ceramics that had had the
edges ground off as needed to get precise values. Coarse alteration
by the flat side of the Dremel wheel, and further fine reduction if
needed by cutting a slot with the edge. Diode switching.

I have photos if anyone wants to see.

Dan - ac6ao
13662 2017-03-05 16:32:41 AD7ZU Re: Disc Ceramic Capacitor "Adjustments"
I for one would like to see some photos
this is one of those hacks that's too good!!

also curious about SMT parts .. 
I have some 1206s I might be tempted to try
probably by grinding a notch or two in the side

Randy
AD7ZU



13663 2017-03-05 18:23:39 bob_ledoux Re: Disc Ceramic Capacitor "Adjustments"
One friend suggested that carbon resistors might be modified by grooving the area between the leads.

bob-N7SUR
13664 2017-03-05 21:02:42 bob_ledoux Re: Disc Ceramic Capacitor "Adjustments"
By the way, I'm not the first poster to mention "capacitor grinding."  Go back to message number 2112.

bob-N7SUR
13671 2017-03-09 19:55:40 Raj Re: Disc Ceramic Capacitor "Adjustments"
At my resistor factory some time in the 80s, the resistors were trimmed to precise values with a diamond file.
This is done without the epoxy paint.

We also made low inductance 50/300 ohms for some clients without a spiral cut going all the way round but
only cutting less than 360 degrees.

Raj

At 06/03/2017, you wrote:
>
>
>One friend suggested that carbon resistors might be modified by grooving the area between the leads.
>
>bob-N7SUR