Re: [Amps] Ten-Tec Centurion

[Bill Fuqua <wlfuqu00@uky.edu>]

        I just took a look at some of the emails on this subject. Saying 
that please pardon any repetition of anything previously mentioned.

        When the amplifier is in idle state what impedances does it see on 
the input and output. Unloaded amplifiers are prone to oscillate at times 
at resonance not necessarily at VHF frequencies. The parasitic suppressors 
only eliminate VHF parasitic oscillations.
        If the cut off bias is removed before the relays make solid 
contact for on the input an output the amplifier may momentarily oscillate. 
Or it may just  amplify the incoming signal and if the output is not 
loaded  (output contacts not closed quite yet) create a very large voltage 
across the contacts.
        Perhaps the problem is that the bias needs simply needs to be 
removed a bit later.

73
Bill wa4lav


At 06:02 AM 11/11/2004 -0800, k7fm wrote:
> Rich said:
>
> "Measuring the actual resistance of the parasitic suppressor resistors and
> eye-balling their appearance could eliminate parasitics as a possible
> scenario in under 2-minutes - if the soldering-iron is hot. Not measuring
> R-supp will not."
>
> Checking the parasitic suppressors at regular intervals is part of regular
> maintenance.  However, logic seems to be against your theory of paratistics,
> in this case.  You explain that hot switching is more likely to precipitate
> the conditions for parasitics.  But, Tom said when he hot switched he never
> had arcing.  Those two facts seem to reduce the liklihood that parasitics is
> the cause.  It also increases the liklihood that timing is an issue.
>
> I do not want to discount your knowledge and expertise, and your success in
> curing stubborn cases of parasitics, but you do tend to conclude that almost
> every amplifier ailment is caused by parasitics.  I happen to respectfully
> disagree with that view.  In some instances, you take a convoluted path to
> conclude that parasitics is the cause, when there are simpler, more direct
> possiblities, that do not involve parasitics.
>
> And, I should warn you, that I do not have many skeletons in my closet that
> you can use to discredit me (at least not that I know of).
>
> But that is what this forum is for.
>
> Colin  K7FM
>
>
>
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