Topband: .TX Mica Caps

[donovanf at starpower.net]

Many of these old transmitting mica capacitors have reliability issues. 
Their foil-mica technology is very obsolete and their molded enclosures 
often leak moisture and contaminants. On the good side, unlike many 
other capacitor designs they're capable of the handling high currents 
and high voltages found in many antenna tuners. 


Its wise to use more modern capacitors if you can. 


73 
Frank 
W3LPL 



----- Original Message -----

From: "Richard (Rick) Karlquist" <richard at karlquist.com> 
To: "HP" <pfizenmayer at q.com>, topband at contesting.com 
Sent: Saturday, February 8, 2020 6:19:21 PM 
Subject: Re: Topband: .TX Mica Caps 

On 2/7/2020 6:15 PM, HP wrote: 
> FWIW -- I was looking at All Electronics website last night - looks like they have 
> unearthed a bunch of WW2 TX micas -at what looks like reasonable prices 
> 
> Reduced Price 
> 0.0004 UF, 5000 VOLTS MICA CAPACITOR 
> CAT# MC-401V5K 
> Sangamo Type F2L Mica Capacitor. 2.32" x 1.25" x 1.73" high. Screw/nut terminals. Mounting holes on 2.63" centers.... 
> [ https://www.allelectronics.com/item/mc-401v5k/0.0004-uf-5000-volts-mica-capacitor/1.html | ] 
> 
> $3.50 each 
> 
> Hank K7HP 

An alternative to these legacy Mica's are: 

Cornell Dubilier (CDE): 

MC (100 to 1,000V) (1 to 2,000 pF) 
MCM (300 to 1,000V) (1 to 1,500 pf) 
MCN (500V) (33 to 470 pF) 
MIN (300V) (1 to 350 pF.) 

All are surface mount 

Available from Mouser and Digi-Key 

I have had good results with these, and they 
are MUCH smaller than the legacy ones. 

Rick N6RK 
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