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Author Topic: Valiant VFO  (Read 2485 times)
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W9BHI
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« on: February 20, 2012, 04:02:02 PM »

Hello all,
I know that the output of the VFO on a Valiant on 160,80 and 40 meters goes  through to the final amp with no multiplying and that 20 meters is multiplied by 2, 15 is multiplied by 3 and 10 is multiplied by 4.
Could you just inject the the actual frequency for 10 thru 20?
Would the multiplier stages tune to the those frequencies?
I want to use a DDS vfo with a buffer and don't want to mess with bandswitching on the DDS.
I may be barking up the wrong tree on this.
Any thoughts?

Don W9BHI
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W9BHI
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« Reply #1 on: February 20, 2012, 04:19:51 PM »

I may have just answered my own question.
I don't think that L5 in the crystal osc,buffer stage will resonate on 20,15 or 10.

W9BHI
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WQ9E
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« Reply #2 on: February 20, 2012, 05:02:54 PM »

The Valiant VFO operates on 160 meters for 160 and 80 meter output and on 40 meters for 40 through 10 meter output (except for 11 which is covered by a separate VFO range).   The 5763 multiplies as necessary to increase the VFO frequency to the output frequency but the final always operates straight through.

For SSB usage, the internal VFO provides drive to the external SSB adapter and then the signal is injected into the 5763 stage which operates straight through on all bands.  It should be fairly simple to modify it so that the SSB input is hard connected to the 5763 grid so that your DDS VFO, assuming sufficient drive, can drive the 5763 either straight through or as a multiplier depending upon your needs.  You can't use the mode switch as is since that wouldn't allow AM.  This also won't work for CW unless you come up with a new keying scheme.

I think it would be better to inject into the 6CL6 buffer/oscillator stage.
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Rodger WQ9E
W9BHI
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« Reply #3 on: February 20, 2012, 05:41:01 PM »

Injecting it into the crystal socket was my main idea.
Would the buffer output circuit work at 14, 21 and 28Mhz?

W9BHI
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