Hi Carl,
Back when, choke input was required to protect the Mercury/Xenon rectifiers
from current peaks they couldn't tolerate.
The transformer will run just fine with modern diodes. Voltage regulation
will suffer a twidge due to the higher R but, if you're only running (real) AM
that's a constant load.
73 & Good morning,
Marv WC6W
http://wc6w.50webs.com/
--- On Thu, 2/19/09, Carl <km1h@jeremy.mv.com> wrote:
> From: Carl <km1h@jeremy.mv.com>
> Subject: [Amps] Vintage rig PS question
> To: amps@contesting.com
> Date: Thursday, February 19, 2009, 6:36 AM
> I recently obtained a vintage 500W self contained 813 TX
> based on a Jan
> 1954 QST article. The rig was built back then but the PS is
> a mix of old
> and new.
>
> The plate xfmr is a UTC CG -305 (this is their high end
> Commercial
> Grade) using the 1750-0-1750 winding with a pair K2AW
> diodes and 8
> 520uf/400V Mallory 'lytics.
>
> Apparently this has worked well for that builder (SK
> unfortunately) but
> Im wondering about the effect on the relatively high
> impedance secondary
> without a choke to limit current spiking. The xfmr is rated
> at 300 ma
> CCS and I'll be running 250ma max. The rig will only be
> used on AM with
> a seperate modulator deck and PS.
>
> A bench test with a Variac and using no load and a 250 ma
> resistive load
> looks good with no more than expected heating after 30
> minutes under
> either condition.
>
> Carl
> KM1H
>
>
>
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