Is there a "best" Capacitor for RF use?

Everything technical about radio can be discussed here, whether it's transmitting or receiving. Guides, charts, diagrams, etc. are all welcome.
Post Reply
MiXiN
proppa neck!
proppa neck!
Posts: 570
Joined: Sun Sep 07, 2014 4:20 pm

Is there a "best" Capacitor for RF use?

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
You do not have the required permissions to view the files attached to this post.

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 818
Joined: Fri Aug 22, 2014 11:34 pm

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

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.
I am as stupid as I look! :|

MiXiN
proppa neck!
proppa neck!
Posts: 570
Joined: Sun Sep 07, 2014 4:20 pm

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

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
who u callin ne guy bruv
who u callin ne guy bruv
Posts: 35
Joined: Tue Mar 07, 2017 8:57 pm

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

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

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

MiXiN
proppa neck!
proppa neck!
Posts: 570
Joined: Sun Sep 07, 2014 4:20 pm

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

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

Top man, cheers Krakatoa :tup

radium98
proppa neck!
proppa neck!
Posts: 649
Joined: Fri Aug 26, 2016 7:01 pm

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

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

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

rigmo
no manz can test innit
no manz can test innit
Posts: 204
Joined: Wed Jan 30, 2019 9:35 pm

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

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
proppa neck!
proppa neck!
Posts: 570
Joined: Sun Sep 07, 2014 4:20 pm

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

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?

User avatar
Bton-FM
tower block dreamin
tower block dreamin
Posts: 444
Joined: Sun Jun 16, 2019 2:55 pm
Location: Beside the seaside

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

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
proppa neck!
proppa neck!
Posts: 570
Joined: Sun Sep 07, 2014 4:20 pm

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

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.
You do not have the required permissions to view the files attached to this post.

Post Reply