On Feb 24, 2006, at 11:01 AM, HAROLD B MANDEL wrote:
> Hi Steve,
>
> In my big amp I use an RJ-2, and in the little amp an RJ-1.
>
> Neither of these are cheap, and there's more to do than
> fidgeting around inside an amp, replacing vacuum relays.
>
> The original Alpha 77 series have an RJ-1 as an output
> relay and a Magnecraft reed relay as the input relay.
>
> Neither of those are simple repairs, and good luck finding
> a replacement Magnecraft reed job. I went with an
> RJ-1 input and RJ-2 output after finding the input relay
> trashed from 30 years of flopping around, and the RJ-1 output
> was iffy because of all the RF amperage going through it and
> I have heard horror stories of '77's cooking their output relays.
>
> The '77 manual says the original setup will track 50WPM,
In my experiences, an RJ-1A will not do 50wpm without a speedup circuit
to decrease its make time from c. 6mSec to 2mS. see
http://www.somis.org/D-a-07B.jpg
> but without a complete refit an owner might expect a fault,
> especially at 20WPM or thereabouts, and what if that fault
> involved a hot switching and a subsequnet 8877 failure?
>
> I dunno, Steve. I think I'd rather go for the MTBF
> reliability side of the curve and let the relays settle down......
>
> '73,
>
> Hal
> W4HBM
> On Fri, 24 Feb 2006 07:40:25 +0000 Steve Thompson <g8gsq@eltac.co.uk>
> writes:
>>
>>
>> Jim Tonne wrote:
>>>> I think I'm starting to get depressed with this exchange . . .
>>>> . . . some others are enjoying it . . .
>>>
>>>
>>> Echos my sentiments. I just came back from Home Depot
>>> after having picked up a fire extinguisher.
>>>
>>> Awaiting the "we're through with it" comment! :-)
>> Going back to a question posed at the outset about relay life... The
>>
>> reflector is not full of people saying that QSK trashes their
>> relays. On
>> the other hand, my mental arithmetic (far from reliable these days)
>>
>> comes up with an estimate of 120-150k operations for a heavy duty
>> contest weekend - a sizeable percentage of expected lifetime.
>> Ensuring
>> cold switching will presumably help, but mechanical failure is going
>> to
>> be a factor at some point.
>>
>> Steve
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>>
>>
>
>
> Harold Mandel
> Superintendent of Construction
> Baran Telecom Inc.
> 606 - 205 - 0172
> hmandel@barantelecom.com
> _______________________________________________
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> http://lists.contesting.com/mailman/listinfo/amps
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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