Well, that's interesting. The symptom was only on two bands... I wonder
what the bias pots had to do with those bands?
In fact, here's a query for other O II owners: In CW mode, I notice that
*only* on 12 and 15 m the transmitter is quite sensitive to any
mismatch. If I don't use the internal tuner, even into a dummy load, I
see a minor reduction in power output and an odd behavior in the ALC
light: as I advance the MULIT control tp adjust PWR output, the LAC
light will *extinguish* when I reach about 97 or 98 and the max power
output will be about 80 W. But, if I first enable the internal tuner and
allow it to find a match, the ALC light will stay lit all the way to 100
and the power output will be ~85 W or so. Does anyone else notice such a
characteristic?
N.B.: I really have no idea what the ALC light is really telling me in
CW mode given that, from what I've been led to understand, the O II
transmitter doesn't use "traditional" ALC.
Kim N5OP
On 7/21/2013 7:25 PM, Robert Mcgraw wrote:
These pots are PA Bias and Driver Bias controls.
A diagnose, remove and replace and re-assemble, followed by a full
"check-out" takes a 2 to 3 hours at least. Then some "burn-in" time and
then a "re-check" is necessary. Yep, 3 to 4 total hours per unit is
quite normal.
73
Bob, K4TAX
Kim, Most likely TT replaced two 1k pots in the final PA. Normally there
are two pots in the RF deck.
Had my Jupiter back to they for service and ot was quick and painless.
Cannot say anything but good
service.
Clayton N4ev
________________________________
From: Kim Elmore <cw_de_n5op@sbcglobal.net>
To: tentec@contesting.com
Sent: Sunday, July 21, 2013 4:36 PM
Subject: [TenTec] Kudos to TenTec Service
I want to hand out kudos to TenTec service: I sent my O II in for service
because of reduced power output and odd ALC behavior on 12 and 15 m. It
took about 2 weeks for it to be repaired and sent back. Total cost of
parts was $12 and labor was $225, so it took someone about 3 h to do the
diagnosis and perform the repair. TT also replaced the RAM battery.
Shipping back to me was $87.53.
The repair lists "Replaced 21k pots in final amplifier," but I don;t yet
know anything more than this. Since I don't have a schematic for the PA,
I don't know what the 21k pots referred to do. I'll call for some details
next week, simply because I'd like to understand better what the nature
of the problem was.
Everything seems to be back to normal and, as an added bonus, TT replaced
the "rubber tires" that encircle the tuning knobs.
Now I need to finish the refurbish on the AL-1200 I scored for ~$1600. I
replaced the bleeder resistors (two were open, but both showed flaws in
the vitreous coating), all the filter capacitors (adding one to the
string), set the B+ to 4kV with the HV transformer tap, added an internal
PIN diode QSK switch and the associated keying loop, and replaced the
dial lights with LEDs. All I need now is a replacement meter switch (on
its way) and I should be cooking with a new amp.
Kim N5OP
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|