Christopher E. Brown wrote:
> On Mon, 12 Apr 2010, Eric - VE3GSI wrote:
>
>
>> Is there an advantage using those 'big caps' when mobile? Perhaps a positive
>> noise reduction from the car electrical/electronics?
>>
>> Courious,
>> Eric - VE3GSI
>>
>
>
>
> Those 'big caps' have too low a SRF to be useful as an RF bypass. *IF*
> you have low frequency ripple making it through to the radios audio stage
> it could help but this would normally indicate a failing battery, and
> could be filtered with a *MUCH* smaller cap.
>
>
You aren't going to find a bigger cap that that battery up front.
73
Roger (K8RI)
>
> The only really useful role would be the same one they serve in a large
> stereo install. As a current reserve.
>
>
> In a audio system they keep the voltage from sagging (causing distortion)
> during current peaks (bass strikes mainly).
>
>
> In a mobile install, there is very little reason if only running a radio.
> Proper size wire will do fine for the 20 - 25 amps a 100watt mobile draws.
>
>
> If you are running say a SG500 amp... A 500watt mobile amp cat hit 70 -
> 90 amps on voice peaks.
>
>
>
> You can run 1/0 cable, you can run #4 or #6 from the main batt to an aux
> batt and 18 inches of #6 to the amp and be OK for AM/FM or dead carrier...
>
> OR
>
> you can run smaller cable with a large audio cap by the amp. The audio
> amp will do nothing for a 70amp+ continious draw, but it will level out
> the supply voltage when transmitting uncompressed SSB (average draw <
> 25amps, peaks to 90amps).
>
>
>
> Personally I favor 1/0 cable and a aux battery, but if one is stuffing
> things into a compact car, or say a jeep wrangler and only runs SSB a cap
> could be viable.
>
>
>
>
> The main issue is when someone installs an 500watt mobile amp at the end
> of a 12 foot #6 run and attempts to drive it to 500watts. The voltage
> drop on audio peaks leads to severe overdrive on peaks and distortion.
>
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|