As best I recall, the MRF-477 final transistors do not have insulating pads
under their tabs. The tabs are emitters and they are directly grounded to the
chassis, unlike most TO-229 transistors where the tabs are part of collector
and must be insulated from ground.
I remember all this because of a talk I had with a Ten-Tec engineer at a
hamfest. He told me about the Argosy finals and how they were different.
Hope this helps.
-de K4CWQ
Sent from my iPhone
> On Sep 15, 2020, at 12:01 PM, Mike Bryce <prosolar@sssnet.com> wrote:
>
> Snowy and the group
>
> on tx you should see about .7V on the bias of both final transistors. Is it
> there?
>
> Mike, WB8VGE
> SunLight Energy Systems
> The Heathkit Shop
> http://www.theheathkitshop.com/
> J e e p
> o|||||||o
>
> A man with one clock knows what time it is. A man with two clocks is never
> sure.
>
>> On Sep 15, 2020, at 11:32 AM, ROLAND HOWELL via TenTec
>> <tentec@contesting.com> wrote:
>>
>>
>> Hi All, just trying to resurrect the above radio, hears just fine but it was
>> lacking, yes it was missing, the PA entirely, i have now acquired one, i
>> have replaced all the 'Q's ( 1 - 5) and the ic.
>> Q1-2 now 2sc2166 not MRF476, as they are the equivalent.
>> Voltages appear correct through out the board, BUT no RF out, i am unable to
>> set the bias with R1 or R2, just nothing happening on my meter. Something
>> not switching on?.
>> During the rebuild i have put insulating pads under Q1-2,5 as they were
>> missing, is that correct?.
>> I have the 13.8 volts when mode switch turned to tune position on the yellow
>> wire.
>> So gents, any and all advice would be appreciated.
>> 73
>> Snowy G0HZE
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>>
>
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