[R-390] Recapping question

[David Wise]

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?
>