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

Tue, 13 May 2003 12:43:41 -0700

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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