[R-390] drill a hole next to or just under the KC tuning

Tue, 13 May 2003 17:44:21 -0400

Darn, now you tell me !!!
I just got it mounted, and only had to drill two holes to find the right
spot.....
Was that "ZERO ADJ." important?

Jim

> Guys,
>
> This thread is nothing but tongue-in-cheek hacking ideas intended to push
> emotional buttons, hopefully of the belly laugh variety. Can anyone
> seriously contemplate putting a 15 Watt rheostat on the front panel to
vary
> the filament current of the oscillator tubes? And even a cursory exam of
the
> archives or Pearls of Wisdom point out that the instant B+ topic is also a
> dead-end, strictly a matter of personal choice. No info has surfaced to
> establish that this would cause tube failure or even shorten their life.
>
> Bob
> Portland, OR
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of [email protected]
> Sent: Tuesday, May 13, 2003 12:27 PM
> To: [email protected]; [email protected]
> Subject: Re: [R-390] drill a hole next to or just under the KC tuning
>
>
> In a message dated 5/13/2003 2:35:09 PM Eastern Daylight Time,
> [email protected] writes:
>
>
> > Is drilling holes permitted or is this an unforgivable heresy?  I'm
> > still debating a couple of 9/64 hole in the rear panel to locate a
> > 220 ohm Dale resistor near the B+ fuse if and when one of the 26Z5 tubes
> > dies and I have to go to silicon. I think that will be
> > better (and easier) than putting it under the AF deck.  I'll repeace the
> > selenum bridge at the same time as it will have to move to
> > make room for the resistor.
>
> Hi Gord. I don't think drilling holes in an R-390/R-390A is unforgivable
as
> long as they are NOT in the front panel, are mostly UNSEEN, are NICELY
DONE
> and for a good practical reason, and can be REVERSIBLE. Drilling 2 small
> holes in the rear panel to hold a power resistor or perhaps to mount an
> IEC-type power connector I would not consider heresy. Drilling a hole in
the
> front panel to mount a toggle-switch I would consider unforgivable heresy.
> The other thing I would add is that if making ANY kind of wiring changes
to
> the radio, PLEASE leave documentation on what you did. It would be very
> frustrating for someone to bring home a radio from eBay or a hamfest and
> find
> several wires hanging out the side of the IF deck with no explanation. Any
> modification done to the radio should make it BETTER. Solid-stating the
> power
> supply with no regard to increased B+ I would consider a BAD modification.
> Adding a power resistor to bring the B+ back to normal is better, but
there
> is still the question of : is it better to have full B+  instantly on all
> the
> tubes before the filaments have had a chance to warm up? In most cases I
> would keep the radio as the original engineers intended. A lot of design
> thought and details went into building the radios by engineers that  had a
> world of experience in all aspects of the radio. 73 Todd Roberts WD4NGG.
>
>
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