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Title: DDS VFO with Viking II Post by: sndtubes on July 31, 2011, 09:55:28 PM Hi Guys,
I have a DDS VFO that I want to use with the Viking II. I have tested it and it seems to work great. I even have it working on all of the WARC bands, 30M, 17M and 12M. The output isn't quite as high, but it works nonetheless. My question is whether it is possible or even advisable to run with the fundamental on 20 meters and above or do I need to double/triple through the buffer. I have tested the VFO injecting the signal right at the VFO jack using the WA1FFL buffer board. I am also using the WA1FFL VFO, but it isn't quite finished yet. (I was using the I0CG DDS-4) 73, Mike WB0SND Title: Re: DDS VFO with Viking II Post by: WD5JKO on August 01, 2011, 07:20:40 PM Hi Mike, So how big is that pile of 6BG6 tubes these days (with 6L6GC guts inside)? OK on the Jim Haggerty DDS VFO. I have his original design here that was in QST. It works but I never did the packaging so it sits in a shoe box. As to your question with the Viking II, you will have to abide by the oscillator and buffer stage L-C resonant frequencies. That pretty much means 160m excitation for 80-160, and 40m excitation for 40-20-15-10 will work. I guess 17 m works on 15 setting, where 6050 Khz for 18150? So what did you do for 12m? Jim WD5JKO Title: Re: DDS VFO with Viking II Post by: sndtubes on August 02, 2011, 12:19:05 AM Thanks, Jim, I figured I would need to use the buffer/osc. stage and abide by the doubling/tripling. I can't remember what I used for 17 and 12, but I think it was in the 6 MHz range. I used the 10 meter bandswitch position for 12 meters (I think). AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
I haven't finished the haggerty VFO yet, but it looks like it's really going to be nice. I'm a bit concerned about the VFO signal in the RX. I'm hoping putting it into a shielded box will help a lot. I don't have the problem with the VFO 122 or other rigs. The T/R switch is a vacuum relay, so the RX is disconnected from the TX during receive. Haggerty suggests that you offset the VFO during receive but I'm concerned it won't switch fast enough (around 30 WPM). I'll see....... I still have about 700 of the 6BG6's. I started off with 13,000 plus. I wouldn't wholesale the last 1000 pcs to the company that bought the lion's share, so I still have a few for retail. 73, Mike |