Swapping Electrolitic cap for tantalum

[W1SFR]

Ok. I got a kit radio transceiver and in the RX section of the transceiver there is a 1uf tantalum cap specified. Unfortunately the cap is missing from the kit. I have plenty of electrolitic caps and would like to make a substitute, but I'm unsure of the value to use and if it's a good idea to make the swap as I read that tantalum caps are more freq stable. The radio is 7.050 so hardly high freq, so maybe no issue there.

Suggestions?

Steve

 

[House0Fwax]

It depends where in the circuit the cap is. However, substitute a 1uF Electrolytic anyway, it won't do any harm.

 

[JimB]

The tanalum cap is unlikely to be in any frequency determining circuit, so at a quick guess any reasonable 1uF cap will do.

Also, why not contact the supplier of the kit and say "The one mike tant is missing" or words to that effect and see if they will send you a replacement.
(Replacement? Is that the correct word for something which was not there in the first place? My brain hurts!).

JimB

 

[WTP Pepper]

You should be OK. Don't ever think of replacing electrolytics with tants in the output of a switching power supply. They can explode.

 

[crutschow]

Just a nit. Tantalums are electrolytic type capacitors.

WTP Pepper: Tantalums may fail if subjected to voltage spikes above their voltage rating, but they are used successfully in high-reliability space electronic switching power supplies when properly derated. The aerospace company I worked for had hundreds of such capacitors in the satellite power supplies we built with no significant failures of the tantalum caps.

 

[mvs sarma]

Ok. I got a kit radio transceiver and in the RX section of the transceiver there is a 1uf tantalum cap specified. Unfortunately the cap is missing from the kit. I have plenty of electrolitic caps and would like to make a substitute, but I'm unsure of the value to use and if it's a good idea to make the swap as I read that tantalum caps are more freq stable. The radio is 7.050 so hardly high freq, so maybe no issue there.

Suggestions?

Steve

you can use normal electrolytic, but try to add a 0.1uF disk in parallel. It can be placed at on solder side

 

[WTP Pepper]

Just a nit. Tantalums are electrolytic type capacitors.

WTP Pepper: Tantalums may fail if subjected to voltage spikes above their voltage rating, but they are used successfully in high-reliability space electronic switching power supplies when properly derated. The aerospace company I worked for had hundreds of such capacitors in the satellite power supplies we built with no significant failures of the tantalum caps.

I think that was the problem. Following a witch hunt after several failed power supplies, the tants where too close in voltage rating to the ouput voltage and nor where they low ESR (schoolboy mistake). It was found the electrolytics where more robust to these spikes and appeared to work. As a result (rightly or wrongly) they were replaced with aluminium electrolytes with twice the overhead in rated voltage. Not a single failure (due to caps) since.