Is there a "best" Capacitor for RF use?

MiXiN · Post by **MiXiN** » Sun May 09, 2021 3:16 pm

I've got a bulk pack of Ceramic Disc Capacitors here that I got from China. A good bunch of them have unreadable values.

I see Ceramic Disc Capacitors being used in our type of circuits (drivers) a lot - so does this mean they're ideal, or is it just because they're cheap?

While I'm on the subject, how do these Philips/Mullard old type Ceramic type fare in RF & general purpose circuits? I used to see a lot of these in RF circuits way back in the 80s & 90s but no longer see them used.

Are they more suitable, & what do the coloured tips denote? IE - black, orange, etc

Screenshot_20210509-150710_eBay.jpg

sinus trouble · Post by **sinus trouble** » Mon May 10, 2021 12:12 am

As far as i know?
Ceramic capacitors are the simplest construction (excluding multilayer) which offer decent stability and voltage handling! So i guess your point of cost is pretty accurate.

Im sure there are more elaborate and expensive versions claiming better specs available?

Interestingly i have noticed that recently the big suppliers (UK) seem to stock less disc ceramics unless its rated for the KV ranges?

Multilayer leaded and SMT versions are more common.

MiXiN · Post by **MiXiN** » Mon May 10, 2021 9:28 am

Cheers Sinus.

I was meant to reply sooner, but everytime I log on the kids distract me.

I've noticed the lower availability of low voltage Ceramic discs, too.

I've been doing a little more research, and it seems Silver Mica is about the best.

Do you know what the coloured tips on the old Philip's Capacitors I posted denote?

Krakatoa · Post by **Krakatoa** » Mon May 10, 2021 3:28 pm

Temperature coefficient. Black is normally NP0, other colors other values.

MiXiN · Post by **MiXiN** » Tue May 11, 2021 2:18 am

Top man, cheers Krakatoa

radium98 · Post by **radium98** » Fri May 14, 2021 7:46 am

seems to me copy of PHILIPS capacitor , what a shame from thoses chineses

rigmo · Post by **rigmo** » Sun May 23, 2021 10:31 am

Silver film high frequency ceramic capacitor are the ones to use for high performance applications that require the most accuracy and dependability.

MiXiN · Post by **MiXiN** » Sun May 23, 2021 11:31 am

rigmo wrote: ↑Sun May 23, 2021 10:31 am Silver film high frequency ceramic capacitor are the ones to use for high performance applications that require the most accuracy and dependability.

I always thought they were called "Ceramic Plate" - usually manufactured back in the day by Philips & Mullard.

Maybe Albert H can shed some light on this?

Bton-FM · Post by **Bton-FM** » Sun May 23, 2021 11:57 am

In exciters, use Capacitors with C0G dielectric (NPO) and you will be fine.

MiXiN · Post by **MiXiN** » Sun May 23, 2021 12:14 pm

Bton-FM wrote: ↑Sun May 23, 2021 11:57 am In exciters, use Capacitors with C0G dielectric (NPO) and you will be fine.

Cheers mate.

Yeah, I've been doing some swatting up on this subject & what you say is right - COG/NPO with black tips.

I managed to source a load of new old stock Hitano NPO ceramic disc Capacitors of different values for about 2p each, so I bought them.

I've also got some NPO ceramic plate Philips/Mullard type.

Is there a "best" Capacitor for RF use?

Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?

Re: Is there a "best" Capacitor for RF use?