Peter -
You can check the bandwidth of the filter by tuning across the
calibrator or other steady signal. As you tune across, the S-Meter
should read low, then rise smoothly to a peak. It will maintain that
peak as you continue tuning for some way in the same direction, and then
drop smoothly down to a low reading again. If you note the frequency
between the two points where the signal drops about one S-Unit from the
peak, you will get a reasonable approximation of the filter bandwidth.
If adjusting the PBT improves the sound, you may need to do the filter
alignment procedure that is attached. There is only one adjustment for
each mode, so you may want to compromise the adjustment for best results
between the 2.3 and 1.8 kHz filters. Essentially these pots adjust the
"FIXED" passband tuning position for each mode. Be VERY careful not to
bump the last, far right pot. Moving it will require a complete
realignment of the transceiver.
73, Garey - K4OAH
Atlanta
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Keong Family wrote:
I have a 1.8 khz narrow SSB filter on my TR7.When using this filter it
is very hard to center on speech and is very echo like.Pressing the
PBT improves things dramaticlly.Filter works great on CW and almost
makes you think it has been mislabelled?Any comments.
Thanks Peter
Zl2PW
The fixed passband controls are located on the power supply board of the TR-7.
Remove the wrap-a-round cover of the TR-7, the power supply board is located
in the right front corner. You will see five small "blue" controls along the
top of this board. They are in the same left to right sequence as the "mode"
switch.
The left most control (you are facing the TR-7) is the AM control, next (going
to the right) is the RTTY control, then the CW control, then the LSB control,
and last the USB control. The control to the far right (sometimes a "black"
control) is the 10 volt adjust control DO NOT BUMP OR ADJUST THIS CONTROL ! !
Once you have become familiar with the controls and their location, proceed as
follows:
1. Select the desired mode to be aligned.
2. Ensure that the PBT button is released.
3. Tune the receiver to the exact frequency which corresponds with the desired
mode.
AM = 13695.0
RTTY = 13697.5
CW = 13694.2
LSB = 13696.4
USB = 13693.6
4. As the receiver approches the desired frequency, a beat note can be heard.
The beat note should be zero when the receiver is on frequency. It may be
necessary to increase the audio gain since zero beat will be on the slope of
the filter and weak.
5. If the beat note is not zero, adjust the corresponding PC control for zero
beat.
6. If additional modes are to be inspected, repeat the above procedure.
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