[ARC5] BC-230, -430 Without AudioPhoolery

[Dennis Monticelli]

Even the lowly 1626 has been noticed by the audiophools. Prices have been
going up.  Fortunately, there are sill quite a few kicking around in our
junk boxes.
I'm thinking you could "push" the 1626's to more power and not worry too
much as we tend not to put many hours on our sets.

Dennis AE6C

On Tue, Apr 20, 2010 at 9:29 AM, David Stinson <arc5 at ix.netcom.com> wrote:

> As you know, the tubes for the SCR-183 / -283 transmitters have
> become golden idols to the AudioPhoolery cult,
> so many of these interesting transmitters stay cold.
> I've been experimenting with the idea of alternate, inexpensive
> tubes.  So far, I've subbed a pair 1626s in the RF stages.
> Jumper 7-8 together fil to cathode and connected that to
> the fil pin nearest the outside of the set.
> These tuned right up, neutralized and put out power
> without a hitch.  They are rated for 250 volts at 25 mils in
> this type of service and the PA puts out
> about 2+ watts at 220 VDC.
> Only trouble- the 1626 is a 12-volt fil tube.  If you have
> a BC-230 and you sub all four tubes, you'll need 24 volts fil.
> If you have a BC-430, it would take 48 volts.
>
> So.... is there a 6.3 volt equiv. to the 1626, that isn't
> an object of cult worship?  6J5 is no-go... too little current
> capacity.  How about triode-connecting an inexpensive
> power pentode, like 6K6 or the like?
>
> What are your ideas?  They will be applicable to other
> rigs that are suffering from cult-inspired amputations.
>
> 73 Dave AB5S.
>
> p.s.  If you decide to work on one of these:
> The 25 mFd filter cap is open.... No.. Really.
> They make them the size of a pencil eraser now.
> The .1 bypasses leak a little, but are still serviceable
> at this B+ in the two sets I've fired-up so far-
> .1 at 350 volts is still big and looks clunky ;-).
> In one set, the hand-made 120 pFd A.R.C. silver mica
> "sandwich" cap with the 30 K-Ohm across it was diseased.
> In the other, it was fine.  In both, the 30-K resistors had
> drifted 15-20% high. Parallelling a 220K across brought
> them down to spec.  Other resistors were within spec,
> except the One Megger (of course).  Lifted one end
> and subbed a new one.
> If you're on 80-75 meters, put a good 1KV NPO 75 pFd
> cap in series with the roller-coil contact output.
> Put the roller about half-way up the coil.
> It will tune right up into 50-ohms.
> Haven't tried 40 yet.
> Move the roller up and down a turn at a time
> and re-tune the tank cap each time for max.  out.
> Keep your power, control and antenna leads short- bypassed
> if possible- or mount the set over a ground plane (thanks Mike H)
> if you have the control boxes.  Otherwise RF will get back into
> the audio leads and you'll FM.  I used aluminum tape (with contact
> tabs, of course) on my wooden base and it works great.
> Neutralize, then "tweek" to min. FMing, just like a BC-375.
> Fun rig.
> Oh... and De-Ox-Id is your friend.
> More later... work calls.
>
>
>
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