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Author Topic: On My Bench Right Now  (Read 3241 times)

RadioRay

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On My Bench Right Now
« on: November 21, 2012, 05:40:15 PM »
Back before Y2K (remember that?)  I built an excellent kit transceiver called the Wilderness Sierra.  It's a multi-band QRP CW transceiver with a superb receiver and puts out about two Watts on transmit.  I carried it around in the Rockiy Mountains and made contacts all over.  It eventually went into my storage and stayed in a box for about ten years.  I pulled it out earlier this year and it still works and does it very WELL!. My only complaint was that the tuning range was limited to about 150 kHz of any particular band.  Fine for CW, but I also wanted to use it for general coverage. Back when this was designed, VFOs were set at low frewuency - usually in the 2 to 3 MHz range and 'mixed' by heterodyne up to your operational frequency. That was because low frequency VFOs were much more stable than high.  This does however, limit the tuning range. 

Entern the 21st century.  We can buy an inespensive Direst Digital Synthesis (DDS) VFO for about $50-75.  The DDS VFO is super stable, accurate and covers from a few Hz to about 50 MHz or higher, depending upon the version.  I built one a few months ago and have been doing exeriments with it (No small animal s were harmed during these experiments...  :P  )  This last week, I grafted this DDS VFO into the QRP rig and it works!  Now I am modifying the front panel it add the DDS VFO into the Wilderness Sierra to get it operating inside of the enclosure.   Later, I will likely add a 10-20 Watt amplifier to the rig so that I can have a nice, portable rig for home and away. Because I am not as 'trail friendly' as I used to be, manpacking anything through 12,000 foot mountain passes is not likely in my future, so building this into a small pelican type case for portable operations is the design goal, once the design ti stable and tested.

That's 'what's cookin' at my bench - you?

DDS VFO KIT:       http://www.pongrance.com/super-dds.html


>de RadioRay ..._ ._
« Last Edit: November 21, 2012, 10:46:25 PM by RadioRay »
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

cockpitbob

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Re: On My Bench Right Now
« Reply #1 on: November 21, 2012, 09:25:33 PM »
Ray, winter is my ham tinkering time.  I recently picked up an old MFJ-9420: 10W of SSB or CW all over the 20M band in a not too large box that draws about 0.1A on receive.  Great Rx and Tx but anything can be improved.

First on my list of improvements is a fine-tune knob on the VFO because the 3-turn knob is just too coarse.  I'm just adding a pot controlled varactor in parallel with the main variable cap.  Then, for CW, a band pass filter because in CW mode it uses the same wide SSB audio bandwidth.  Last (maybe) an RIT knob.

The bad news is I think I'm wasting my time.  I promised my 14 year old son that if he passed the 5wpm test he could have a QRP rig in his room.  I don't think I'll get to keep it long.  Our ham club starts its CW class in Jan.  BTW, the little brat got his Tech and General when he was 11!
« Last Edit: November 21, 2012, 09:28:07 PM by cockpitbob »

RadioRay

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Re: On My Bench Right Now
« Reply #2 on: November 21, 2012, 09:31:27 PM »
Congratulations on BOTH counts- actually!  That MFJ rig is fine by me, other than the tuning speed that you mentioned.  I had one and added the CW accessory and frankly, it received good audio reviews from on the air contacts. The Ten Watts on SSB is greatly improved by their audio processing.  It's one of the devices that MFJ can be proud of.  If I had one today, I'd probably install this DDS VFO . . . ha ha



>Ray
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

cockpitbob

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Re: On My Bench Right Now
« Reply #3 on: November 21, 2012, 09:47:06 PM »
Tell me more about your DDS VFO.  Was it a kit?

RadioRay

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Re: On My Bench Right Now
« Reply #4 on: November 21, 2012, 10:47:51 PM »
I repaired the link to the DDS VFO kit in my first posting.  Sorry - it was not working before. 

Here is is again.

http://www.pongrance.com/super-dds.html


The kit went together VERY easily and does a good job.


>Ray
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

cockpitbob

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Re: On My Bench Right Now
« Reply #5 on: November 21, 2012, 11:08:27 PM »
That VFO and freq display looks really nice.  Now I'm torn between my normal minimalist leanings and adding lots of extra features.

Also Ray, you mentioned a 10W-20W amplifier.  Do you have one in mind?  Ramsey sells single band 20W amp kits for $45 that get good reviews, except for inadequate heatsinks.  I'm thinking that would go well with a 2W shirt pocket rig.

Radio Preppers

Re: On My Bench Right Now
« Reply #5 on: November 21, 2012, 11:08:27 PM »