according to the tentec code for serial numbers:
amplifier s/n 5b10053
means:
5 = may
b=separator
1=production run for that month
034 =unit number for that run
9=year of manufacture
jack
ak7o
----- Original Message -----
From: "K0BX" <k0bx@arrl.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Thursday, February 05, 2009 5:44 PM
Subject: [TenTec] Centurion 422 Bias Circuit Solved
> Last night I wired up the cable for my Icom IC-756PROIII to do break-in
> CW. CW keying to the 422, 422 to the rig.
>
> So let me try to explain what I was looking for.
>
> 1. In SSB, if you key the mike with no audio, you get a plate current
> of about 100 to 150 ma, 1/2 way between 0 and .2 ma. This is normal for
> SSB.
>
> 2. In CW, using breakin, the older models of the 422 would put the amp
> in transmit and draw the 100 ~ 150 ma when it was in between keying.
> Like you are waiting for the DX station to say QRZ again.
> This would cause a lot of heat from the tubes. See the QST Review on
> the 422 from 1991.
>
> 3. What I found is the later, models of the 422 that are greater than
> the one in the QST Review does not do this. Instead there is no idle
> current in breakin during the pause for QRZ.
> I guess I should have waiting to ask the question until I had the wiring
> completed. I had this heat problem with my Drake L-7 and Ameritron
> QSK-5. It would lock the amp in xmit and just go around it for receive
> but you
> could see the 150ma on the plate meter.
>
> The last question I had was about the serial number and the date it was
> built. From what I have found is that S/N with 'A' in it was before
> year 2000. The last number of the S/N is the year.
> So mine would have been built in 1992 and was the 004th on of that
> production run. Any ideas if I am close or not??
>
> Thanks for all the inputs
>
> Joe K0BX
>
> Carter wrote:
>
>>k0bx@arrl.net wrote:
>>
>>
>>> I just received a 422 Centurion. My question is: How do I determine
>>> if the newer Bias circuit is installed?? This circuit cuts off the
>>> bias when the rig is in transmit but is in idle.
>>>
>>>
>>
>>I think you sort of answered your own question.... if it's in transmit
>>but idle, plate current should be zero. Going back 10 or 12 years ago,
>>my bias board failed and then there was about 300 ma of plate current in
>>idle. You could take it out of its case and check the revision suffix on
>>the board (see below). Otherwise, I don't believe there is an easy way
>>to tell.
>>
>>I had the original bias board that failed; as of ten years ago, I
>>believe TT had a -B and then a -C rev of the board.
>>
>>Note: all of the above is subject to the vagaries of my memory. <grin>
>>
>>
>>
>>> QSL review from 1994 S/N 10A10091 had the old bias circuit and they
>>> indicated that the newer one had the modifiy circuit. My S/N is
>>> 80A10042. But no date of purchase was indicated in the manual. Any
>>> ideas? Any ideas on when the 80A10042 was built?
>>>
>>>
>>
>>Probably ask TT.
>>
>>It's a nice amp! Enjoy it.
>>
>>73,
>>Carter K8VT
>>
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>>TenTec mailing list
>>TenTec@contesting.com
>>http://lists.contesting.com/mailman/listinfo/tentec
>>
>>
>>
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