[R-390] Recapping question

[n4buq at knology.net]

Actually, lug B has a few more component soldered to it which is why I was 
considering moving it away from there so it wouldn't have eliminated that 
lug by running the cap in question to somewhere else.  I like the A to D 
route too and may use that.

Yes, it's water under the bridge alright.  I got started with the wire 
clippers and just couldn't stop myself :)  I have some very small 0.0047 
1kv ceramics that make for a lot more room and will be using those in their 
place.  Yes, I realize 1kv is way overkill, but I happen to have them and 
they are quite small so I'm going with them.

I've done pretty much the same thing in another crystal deck I have without 
much change in the output.  This one seems to be rather weak on several 
bands and am hoping I'll see a small increase in output for my troubles.  
The new plate resistor and screen resistors will hopefully have the most 
effect, though.

73,

Barry - N4BUQ

On Wed, 6 Sep 2006 11:39:49 -0700, "David Wise" <David_Wise at Phoenix.com> 
wrote :

> Ceramics hardly ever go bad, but that's water under the bridge.
> 
> At 455kHz, the lead length and dress are not critical
> to the extent that any of the connections you mention
> would cause different behavior.
> 
> My opinion: First, to make it easier to remove the
> transformer, and to minimize the possibility of
> damaging it from soldering heat, it's desirable
> to minimize the number of wires per terminal.
> A-B is one tick better than A-C.  Second,
> the A-B connection has a smaller chance of B+
> getting shorted to ground than A-D, because the
> latter is stretched across more stuff.
> 
> In this case, neither of the above arguments is
> compelling, but they could have saved a penny
> and left out lug B.  I would have assembled it A-D.
> 
> FWIW,
> Dave Wise
> 
> > -----Original Message-----
> > From: r-390-bounces at mailman.qth.net
> > [mailto:r-390-bounces at mailman.qth.net]On Behalf Of n4buq at knology.net
> > Sent: Wednesday, September 06, 2006 11:19 AM
> > To: r-390 at mailman.qth.net
> > Subject: [R-390] Recapping question
> > 
> > 
> > I'm replacing some high resistors in the crystal deck and in 
> > the process, 
> > am replacing some of the bypass caps.  I suspect they could 
> > be partially 
> > responsible (due to leakage) for the resistors going high.  They are 
> > the "Erie" brand disk ceramics and their outside surfaces 
> > have turned to a 
> > sticky, waxy feel which make me think they could be 
> > comprimised (not sure 
> > about that).  I decided that while I was in the area I'd replace them.
> > 
> > My question concerns the placement of one of the caps.  In 
> > the following 
> > image, the original cap was connected between point A and the 
> > grounding lug 
> > at point B.
> > 
> > http://www.knology.net/~thelanding/crystaldeck.jpg
> > 
> > I'm curious why they wouldn't have chosen to put the cap 
> > right across the 
> > transformer at points A and C.  It seems it would have made for less 
> > clutter in the other area.  Also, from point A to point D 
> > might have been 
> > just as convenient.
> > 
> > Is there a good reason to go with A to B?  Maybe it is better 
> > to have the 
> > components soldered to a common ground point?
> > 
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