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[TenTec] RIT or Tunable BFO Mod for Omni V]

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Subject: [TenTec] RIT or Tunable BFO Mod for Omni V]
From: n4lq@iglou.com (Steve Ellington)
Date: Thu, 30 Oct 1997 20:39:17 -0500
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  I received so many request for this that I am reposting it.
Another advantage to this over using the split mode is retention of the
fast qsk capability while allowing RIT type operation on cw.   N4LQ

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Message-ID: <3428957F.45A6EBB6@iglou.com>
To: <tentec@contesting.com>
Date: Wed, 24 Sep 1997 00:22:24 -0400
From: Steve Ellington <n4lq@iglou.com>
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To: tentec@contesting.com
Subject: Tunable BFO Mod for Omni V
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Mod: Provides a means of varying the bfo frequency on the CW and LSB

History: The Omni V has no RIT. Offset tuning is accomplished by
operating constantly in the
             split mode. This is cumbersome. Installing a real RIT
control would be overly complex.
             This mod provides the next best thing.

Application: Omni V

Likely Users: Good CW men who love the Omni V

Specs: Allows frequency of bfo oscillator to vary over a 600hz range.

Purpose: 1 .To allow changing the audible pitch of incoming cw signals
without engaging
                  the "split" mode.
              2. Allows the operator to change the bfo offset at will
for a more comfortable
              3. Increases convenience during NET operations allowing
one to ( tune in) off-
                  channel signals and quickly QSY to another frequency
without pushing the
                  split and a=b buttons.

Parts Needed: 1ea. NTE612 Varactor
                       1ea. 68pf disk ceramic capacitor
                       1ea. 12k 1/4 watt resistor
Parts Cost: $2.50

Test Equipment: Frequency counter.


1. Remove C3 from the transmit audio/bfo board. If you are careful and
lucky, this cap can be
    crushed with pliers and the remaining lead used as a connecting
point for the new cap. Otherwise,
    you will need to remove the board. The latter makes for a neater job

2. Solder the anode lead of the NTE612 to the ground lead of R21

3. Solder a lead of the 68pf cap to the cathode lead of the NTE612

4. Solder the other lead of the 68pf cap to the ungrounded lead of the
former C3.

5. Locate the IF/AF board. Locate connector 53. Pull the wire out of the
center pin. This wire
    comes from the wiper of the notch control and provides a variable
source of dc regulated
    and well filtered voltage. Other controls could be used but would
prove more complex.

6. Extend this wire up through the large hole in the back of the chassis
up to the tx audio/bfo

7. Solder the 12k resistor to the end of this wire.

8. Solder the other end of this resistor to the junction of NTE612 and
68pf cap.

9. Set the notch control to the center position.

10. Connect the frequency counter to the hot side of R30.

11. Apply power to the rig and adjust C4 for exactly 9mhz.

12. While you're at it, adjust C6, C7, C10 and C9 per instructions on
page 6-57.

Note: If the 250hz filter is used, the PBT may need readjusting when the
bfo is varied over a wide

For those who like the notch function. The tone control or squelch could
be used since they are all 10k pots. The regulated voltage source can be
applied to the top of either pot and the bottom end grounded. The wiper
can then be routed as previously outlined.

For you who like the looks of a good mod may I suggest drilling a hole
and mounting a new pot right in the middle of the word Ten-Tec on the
front panel. Rename the rig Omni V+. This should increase it's value at
least $300. I suggest a bright red knob with BFO written on it with a

Need Help? Be glad to!  73

Steve N4LQ


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