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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