[Boatanchors] BC-1004, Bringing up BA Slowly via Variac

[Al Parker]

Hi Phil,
    You oughta check the voltage divider/bleeder(s) in the p.s. b4 you
start.  They've often drifted high in resistance & you'll have much lower
screen voltages than expected.  (and probably ck the filter caps'
resistances, they're oil filled I think, not electrolytic, if so, you
don't need to go too slow for their benefit.)
    I've usually seen some B+ coming up at 50-70% of line voltage, & I
don't worry abt hurting the rectifiers, we're not talking abt real high
voltage, high current stuff.
    Let us know how it comes out, you'll have a nice bandcruiser.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info


----- Original Message ----- 
From: "Philip Atchley" <beaconeer at sbcglobal.net>
To: <boatanchors at mailman.qth.net>
Sent: Monday, January 24, 2005 2:28 PM
Subject: [Boatanchors] BC-1004, Bringing up BA Slowly via Variac


> Hi All,
>
> Well Finally!  After some months of overhauling this Hammarlund BC-1004
> for a friend it's in the process of "bringin' 'er up slow" <grin>.
>
> For some reason, I'm not sure why, the re-cap and overhaul of this set
> has taken FAR longer than any BA that I've ever done.  Perhaps the sheer
> size and weight of the set AND it's outboard power supply has been
> intimidating.  Who knows.
>
> Anyway, I haven't been into the power supply at all.  The owner of the
> radio had already brought it up and tested it.  HOWEVER, I am still
> bringin' 'er up slowly.
>
> The owner said that he ALSO replaced the 5Z3 with silicon units. I'm not
> sure why, if he were going to go to the trouble, he didn't replace BOTH
> tubes with silicon rectifiers.  On the same subject.  The schematic I
> downloaded doesn't show a 5Z3, it shows a 5U4 and 5Y3 tubes,
>
> I realize that the remaining tube rectifier won't start conducting till
> it's filaments reach a certain temperature.
>
> A couple quick questions.
>
> 1.  At about what point (percentage of rated line Voltage) can I expect
> this to begin to occur?
>
> 2.  Do I need to worry about the filament of the tube being
> stripped" by having Voltage (al-be-it below normal) on the plates while
> the filament is still too cool to "squirt electrons"?
> 73 de Phil,  KO6BB
> 991 Different NDB's heard to date.
>
> http://www.geocities.com/ko6bb/
> Merced, Central California, 37.3N  120.48W  CM97sh
>
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