Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jul Sun 25, 2021 10:30 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 7 posts ] 
Author Message
 Post subject: what is this component?
PostPosted: Jun Sun 13, 2021 8:34 am 
New Member

Joined: Mar Thu 25, 2021 2:43 am
Posts: 17
Hi all. I have a question, can anyone tell me what this component (attached) is please? It's in a Kreisler radio 11-71 and 11.81 and i think it is a capacitor or trimmer.
Does anyone know where i can get one from please?
Regards.
Paul.


Attachments:
File comment: Top RH corner of the photo
Kriesler 11-81A radio.jpg
Kriesler 11-81A radio.jpg [ 488.21 KiB | Viewed 623 times ]
Top
 Profile  
 
 Post subject: Re: what is this component?
PostPosted: Jun Sun 13, 2021 9:15 am 
Member
User avatar

Joined: Mar Sun 22, 2020 5:56 am
Posts: 1875
Location: Arvada, CO, 80004
Your assumption is correct. It is a 56PF capacitor. You can get one from Ebay, or from one of these vendors:------------------------->

_________________
Electronics are filled with smoke. It’s my job to put the smoke back in when they fail.
Cheers,
Jay


Top
 Profile  
 
 Post subject: Re: what is this component?
PostPosted: Jun Sun 13, 2021 2:16 pm 
Moderator
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 9547
Location: Latham NY 12110
These are temp compensating type caps and very reliable, leave it be


Top
 Profile  
 
 Post subject: Re: what is this component?
PostPosted: Jun Mon 14, 2021 4:25 pm 
Member

Joined: Jun Fri 19, 2009 6:34 pm
Posts: 10709
Location: Long Island NY
Answer to your question, you cannot buy anything like that any more, nor should you have to unless it is physically broken. It's a tubular ceramic capacitor that likely had specific temperature and voltage characteristics to keep the radio stable with temperature changes. The radio manufacturer selected them for that particular application, and would be the only source of exact replacements. Inexact replacements are possible (i.e. stick any old 56 pF capacitor in there) but then the radio may drift or malfunction in other ways.

_________________
"Hell, there are no rules here--we're trying to accomplish something!"

Thomas A. Edison


Top
 Profile  
 
 Post subject: Re: what is this component?
PostPosted: Jun Mon 14, 2021 9:19 pm 
Moderator
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22427
Location: Somers, CT
As is the white ceramic tubular beneath it. Best source is Surplus Sales of Nebraska, but finding one with the exact tempco may next to impossible. They rarely go bad.

_________________
Just because it can be done doesn't mean it should be done.


Top
 Profile  
 
 Post subject: Re: what is this component?
PostPosted: Jun Mon 14, 2021 9:43 pm 
Member

Joined: Jan Tue 16, 2007 7:02 am
Posts: 4577
Location: Lexington, KY USA
I wonder about the termination for the inner electrode. The photo just shows darkness in that area? Is there a short bit of metalization on the outside surface and a second wire? As seen on the 56pF part?

If you have to replace one that has been broken, and do not have complete information, you will need the capacitance value, at least. A reasonable substitute might then be an NP0 / C0G ceramic, or a silvered mica capacitor. This will probably be OK for a consumer radio. At worst you get a bit of drift with temperature.

It is not as if they had some magical ceramic material years ago that cannot now be found. Present day dielectrics are as good or better. Discs, or multi-layer capacitors work as well as the tubular caps, they just look different. (And no doubt cost less to make.)

Can you give us a link to information on this radio? The schematic and parts list will often provide some clue about the components.

Ted


Top
 Profile  
 
 Post subject: Re: what is this component?
PostPosted: Jun Tue 15, 2021 1:05 pm 
Member

Joined: Jun Fri 19, 2009 6:34 pm
Posts: 10709
Location: Long Island NY
Quote:
It is not as if they had some magical ceramic material years ago that cannot now be found. Present day dielectrics are as good or better. Discs, or multi-layer capacitors work as well as the tubular caps, they just look different. (And no doubt cost less to make.)


Short of doing a chemical analysis on it there is no way to know if the ceramic is one of the ones still in use today. There were hundreds of ceramic formulations used to make capacitors, many of which were unique to particular manufacturers who disappeared without leaving their data behind. Indeed, the more familiar designations like C0G, N750, or Z5U were intended to bring some standardization to a chaotic situation, but not everybody adopted those right away. Aside from composition, the sizes and shapes of those capacitors helps determine how they respond to changes in temperature. Designing them was a real art form, one that is long gone. Everybody uses digital PLL tuning now! Disc capacitors won't ever be the same, and MLCC capacitors have all sorts of parasitic problems at higher frequencies.

When radios were manufactured, only the smallest, weakest companies went to distributors like Allied or Newark and bought off-the-shelf components. Anybody with any buying power went direct to the component makers and contracted for what they needed. If standard production parts could be used that was fine, but if they needed some with custom characteristics most component companies were happy to do special orders. We don't even know if the caps in the OP's radio are standard values, let alone if they had any unique characteristics or features. The schematic will only have the pFs and maybe the volts, and the parts list will only tell you the replacement part number which probably went NLA more than half a century ago. The additional data was probably in an engineer's file folder that got chucked when factory support for the radio ended.

_________________
"Hell, there are no rules here--we're trying to accomplish something!"

Thomas A. Edison


Top
 Profile  
 
Post New Topic Post Reply  [ 7 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: Google [Bot], Tin Omen and 11 guests



Search for:
Jump to:  


































Privacy Policy :: Powered by phpBB