[TenTec] Paragon Finals and other woes

[Bwana Bob]

Thanks, Pete,

I'm thinking maybe the Astron was putting  out too much voltage. I don't 
trust Astron supplies and don't have any in my shack. In general, I 
don't like running a radio on a power supply that has front panel 
variable voltage and current.  It's just too easy to make a mistake and 
it appears that this Paragon failed on turn-on.  I'm going to disconnect 
the B+ wire that powers the final and see if the rest of the rig powers 
up. The ohmmeter doesn't show a dead short, so maybe something is 
breaking down with applied voltage.

I will also repair the Ten Tec power supply to take the Astron out of 
the picture.

73,

Bob WB2VUF

On 1/29/2019 8:43 AM, Peter Bertini wrote:
> If the PL issues are resolved, I'd fix the radio, or sell it for parts.
>
> The Paragon rigs are aging beasts, and even buying another Paragon may mean
> you end up with TWO parts radios in short order!
>
> But, back to this unit. My only experience is with my Paragon II, which is
> a more reliable radio.
>
> The TenTen power supply should be repaired and used with the radio. It
> provides high current limiting which protects the expensive finals from low
> impedance loads. The Astron would be  poor choice.
>
> Regarding the MRF-458 transistors, it is my understanding that the MRF-454
> devices have similar gain, but are rated for higher collector currents. You
> may want to check around with someone with more knowledge to see if the
> MRF-454 would be more reliable.
>
> The short on the DC bus could be related to other work, a pinched wire,
> etc.  I'd want to prove that the PA was the cause of the short before
> taking any drastic action, or needlessly replacing expensive PA
> transistors.
>
> Every Omni VI I've picked up over the past few years, all five of them,
> have had issues... some subtle, some major. I will eventually just keep the
> best two on the operating bench, and keep two for spares. The earlier VI
> will get sold. I think almost any vintage TenTec should be approached with
> the expectation that there will be a problem in the rig if you look hard
> enough, or there will be one soon.
>
> regards
>
> Pete  k1zjh
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