how to connect DDS VFO to dx-60?

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kf6pqt:
I spent my last day of freedom ("recovery day" #2, gotta go back to work tomorrow, the GF and I went to Hawaii for a week!) building the Norcal FCC2 DDS VFO.

How to connect it to the VFO input of my DX-60? Just a coupling cap?

I googled, and I searched, but here i iz ax'ing da ques-chun.

And yes, this was my first time to KH6 land, and man, do I wanna move there!

Thanks,
Jason kf6pqt


...no, still haven't touched the DX-100 yet, hope to this weekend.

John K5PRO:
You probably need a buffer stage, like a 2n5109 transistor, a la handbook, with a step up impedance transformer on the collector, to drive the input with some voltage. Also does the DDS stay on all the time? Might need to switch a stage on and off to prevent sidetone during receive.

KA8WTK:
Hi Jason,
  The FCC2 is a neat little device. I built one myself but have not used it as a VFO source for a transmitter. John, I think, is correct as you would need some sort of buffer/amp/impedance circuit between the FCC2 and the DX-60. The HG-10 VFO puts out about 5 volts peak-to-peak and, if memory serves, that is into a 50k load. The FCC2 is output into a 50 ohm load.
  One other concern is the spectral purity of the FCC2. I say concern because I have not seen any data on the web about how clean it is from the usual DDS spurs.
  Just more to consider.....

Bill
KA8WTK

John K5PRO:
You can get a 5 volt swing, with a 2N5109, maybe with 12 VDC collector Vcc. A small toroid for the output transformer will get you what you want for sure. These things are common in most of the ARRL handbook VFOs and the newer ARRL books like the excellent Experimental Methods in RF Design by Haywood, Campbell et al. I built a few on tiny piece of vectorboard, for a friend who was running a different DDS with an old Heathkit. Also used one for my DX100 for a while on the solid state VFO project which i gave up on (due to stability of VFO in that package). I have the same DDS that you have, haven't built the kit though, planned for a DX100 refurb.

73
K5PRO

KF1Z:
Quote from: KA8WTK on February 29, 2008, 12:41:41 PM


  One other concern is the spectral purity of the FCC2. I say concern because I have not seen any data on the web about how clean it is from the usual DDS spurs.
  Just more to consider.....

Bill
KA8WTK


I've used mine to drive my class-e transmitter......

The spurs were 75db down from the carrier....

Not too great for high-power/quiet band conditions....
Noisy conditions you'd go unnoticed I bet.

"Legal" yes  (>45db).... 

For 100 watts output or less,,, I'd say good enough...

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