Basically, electrolytic caps start their life of deterioration from day one.
As the electrolytic begins to vent and thus dry the value of the C
decreases. Some have slower deterioration than others thus likely those
being of better quality. There's several factors which contribute to making
this better or worse. Internal heat, voltage applied, ripple content or
signal content and such. Even these items have a valid "shelf life".
Yes, some caps are better at serving as power supply filters, some serve
better as bypass for Vcc and some better for signal paths. As they say,
"all electrolytics aren't created equal".
As to the Omni V filter, can't say, never owned one. However I found the
audio filter in the Paragon and Paragon II that I owned worked quite nice.
73
Bob, K4TAX
----- Original Message -----
From: "Steve Berg" <wa9jml@tbc.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, September 12, 2007 11:20 PM
Subject: Re: [TenTec] Fragile Radios
>I have a really nice Omni V and have never been able to make much use of
> the audio filter in the rig. Instead, I use a Autek external filter to
> good effect. Does anyone here know if this could be a problem with
> older electrolytic caps? Since I plan to use this rig for many more
> years, would it be advisable to recap it like Joe has suggested? I also
> have done this many times with my older boatanchor radios.
>
> Steve WA9JML
>
> Joe Roberts wrote:
>> On a related note, I wonder whether early digital gear like Omni V ages
>> so well. Specifically, wondering about the electrolytic capacitors.
>>
>> Case in point: Picked up an Omni V and the potential was there but I
>> found it to be a rather hissy and spitty set. NOT pleasurable to listen
>> to. Too much high frequency garbage. Made my ears hurt.
>>
>> Contrary to the "If it ain't broke" law, I decided to replace a few
>> strategic caps on the logic board with super low ESR motherboard caps
>> like Rubycon MCZ and Sanyo Oscon. Wow, spurious noise level went way
>> down.
>>
>> Emboldened by this result, I recapped the entire IF/AF board with
>> similar quality caps. WOW WOW WOW. The V is now super quiet and real
>> well behaved. The difference is NIGHT and DAY.
>>
>> Two questions:
>>
>> 1) Were really good electrolytic decoupling caps for digital available
>> in 1989?
>>
>> 2) Are the yellow IC caps Ten Tec used even on the same planet
>> quality-wise as 2007 low ESR, HF rated caps.
>>
>> I think not. I figure Ten Tec used good quality, but not exceptional,
>> 1989 commercial grade parts....and these are getting rather long in the
>> tooth to boot.
>>
>> A rig like the Omni V is digital and needs good caps and the ones in the
>> radio were probably not the greatest then and certainly aren't now. My
>> theory is that the marginal decoupling capacitors are part of the blame
>> for some of the noisy rigs out there.
>>
>> Reminds me a lot of recapping old boatanchor radios, which I did a lot
>> of. Yanking out some funky wax caps and putting in Orange Drop 715Ps
>> really brought these old radios to life.
>>
>> Time files...maybe we should start thinking about some of the 80s rigs
>> in the same light. My experience is that putting new, fresh, & really
>> fancy capacitors in the Omni V vastly improved the radio, and I only hit
>> a few of the high spots with the replacements. Will probably do the
>> whole radio over time.
>>
>> I can now say that if an Omni V is at all noisy, it is not working right.
>>
>> When I was messing with vintage tube radios, I struggled with the idea
>> of keeping them original, but for radios I wanted to use, I usually
>> went ahead and recapped because the performance gains were so high.
>>
>> I am following the same logic here with, so far, very positive results.
>>
>> Joe N5KAT
>>
>>
>>
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>>
>>
>>
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