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Re: [TenTec] Corsair II realignment: DIY?

To: tentec@contesting.com
Subject: Re: [TenTec] Corsair II realignment: DIY?
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 02 Jan 2011 19:18:48 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>

On 1/2/2011 8:05 AM, Joe Roberts wrote:
> On 1/2/2011 2:20 AM, Dr. Gerald N. Johnson wrote:
>> Mouser carries Vishay-Sprague Atoms. They seem to be the same high
>> quality they originally were. Much larger for better heat dissipation
>> than the miniatures too.
> I believe they are now a big can with a little cap tucked inside. I use
> them in guitar amps, which is probably their biggest market. They are
> now super light for the size...used to be they felt like a battery!

Could be. Still the last I checked their ripple current ratings were 
greater than the super compact electrolytics.
> Nichicon and Chemi-Con make much better HV caps (long life, low
> impedance) but they are going to be small radials, not big chunky axials
> that look right and fit vintage tag strip layouts.
> Best grades of axials today might be the ones made by Vishay/BC
> Components with the blue transparent wrapper (used to be Philips)
> http://www.vishay.com/capacitors/aluminum/aluminum-axial/
> No idea where to get the high grade versions in small quantities from a
> distributor. You also have to watch the size with axials...the ones TT
> used in Tritons and Omni Cs were miniaturized even by today's norm.
>> I hadn't considered drilling new holes in the board to use radial caps,
>> but I think I'd be inclined to have spliced one of the leads on a radial
>> cap so it could routed to the original holes.
> That was my inclination also. Radial leads will usually span the axial
> holes. However, providing appropriate holes for radials looks better and
> is more mechanically stable. I had visions of shorts when installing
> radials with 2 or 3mm spacing with long unsecured leads. The leads are
> mighty close together on a 1uf radial cap.

> Also, a long lead could have more reactance at/above 30mHz than the
> capacitor itself. Many of these modern digital-ready caps, like Os-Cons
> and motherboard caps, are very low Z well into the VHF range.  A 1/2"
> lead would be significant in this regard, degrading the performance of
> the cap.

True, though the elderly electrolytics were not a great benefit for RF 
or even IF bypassing so lead length wasn't considered in the design.
> Plus, in about 30% of the cases, I could find a shorter path to ground
> with a new hole, further shortening the leads. It might not matter all
> that much, but the performance boost is free!
> Joe N5KAT
73, Jerry, K0CQ
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