RAN Technology

Universal Frequency Converter


Technical 0 Comments 03/17/2022 

Modify as needed

Posted By: Robert Nickels (ranickels)

I found myself wanting to convert various frequencies to other frequencies and wanted a cheap and easy solution, so I designed a simple "universal converter" using the NE-602 and a programmable oscillator from Epson.  I'd used the same combination in hundreds of "RANVerter" SDR Upconverter projects since my Dec. 2013 QST article and knew that while there were limitations, this was a good combination for a simple yet functional solution.

The NE-602 is well understood to have a limited dynamic range, but on the other hand provides useful conversion gain that more than offsets mixing losses and on the lower HF bands at least, makes an RF amplifier unnecessary.    The Epson oscillator outputs a square-wavish TTL level signal which purists complain is not ideal for use as a local oscillator but which provides good results regardless.    The output is attenuated to meet the LO input requirement of the 602, otherwise it's straight off the datasheet and many 602 app notes that are easily found.   I included a 5 volt regulator so the converter can be powered from existing 12VDC power sources or with a voltage double running from a 6.3VAC filament line.

My input filter is totally inadequate - yet works well!   Just a fixed inductor and resonating capacitor for the band of interest and a couple of turns to link couple to the low-impedance antenna.    Thanks to the conversion gain of the NE-602 the resulting sensitivity when used ahead of a Command Set or boat radio is sufficient to hear every signal that is there to be heard.   Obviously better front-end selectivity would be a plus, and a double-tuned preselector should be a good solution or a low-pass filter could be used to knock out  an image.   

Here's an example of using this converter to shift the 455 kHz IF froma  little shortwave receiver to 3395 kHz where it is displayed on a Heathkit SB-620 panadator   VIDEO

Another video example of the universal converter used to convert the 75 meter ham band down to the range of I2PHD's Arm Radio:

As noted on the schematic, the Epson oscillator can be ordered from DigiKey by specifying the desired LO frequency IN MHZ in the "Order Notes" box on their order entry form.   It is a value-added part so will show as "backordered" but typically it takes a day or less for them to program your frequency into the chip.

 

Click on the image title or on the image itself to open the full-sized image in a separate window.

    Visitors to the Elgin National Historic area along the Fox River in Elgin Illinois may not realize they are at the site of a famous shortwave radio station - W9XAM - the time signal station operated by the Elgin Watch Company.Elgin was the only watch company maintaining an observatory that observed, recorded and broadcasted time from the stars correct to the hundredths of a second. Located a...  READ MORE
- Robert Nickels (ranickels),  05/09/2022 
  

The Mosley Commando II

Made in England and scarce even there
Category: Vintage Ham Radio
The Mosley CM-1 receiver is quite well known and not especially hard to find in the US even though it was the only radio produced by the company that has been well-known for antennas since 1939.   Or is it...?A full-page ad (advert for you on the other side of the pond) appeared in the RSGB Bulletin in 1963 for a nice looking and very capable SSB transmitter called the "Commando II&...  READ MORE
- Robert Nickels (ranickels),  04/15/2022 
   I'm not ready to publish a description of exactly HOW it works, but 20 minutes effort with scissors and tape produced a prototype  Droplet Energy Generator that allows me to say for sure that IT WORKS!I duplicated the design shown in this video.   I wrapped a scrap of plastic in aluminum foil, then applied a strip of double-sided tape and to that attached a piece of PTFE thread-...  READ MORE
- Robert Nickels (ranickels),  03/30/2022 
   When I was first licensed in the 1960s in Nebraska, two groups of hams were commonly heard on the air before those with jobs got off work - other teens like me and the disabled hams.   Some of my earliest Novice ham buddies were blind students at the Nebraska School for the Blind in Nebraska City, and there were many other visually-impaired hams, all of whom were exceptional operators, e...  READ MORE
- Robert Nickels (ranickels),  03/21/2022 
   Old style mica capacitors were used in the pi-net matching sections of several vintage transmitters and the combination of age, heat, and high RF currents have made them likely failure items.   My Collins 32V-2 transmitter was to the point where it would not properly load to full power on 75 meters so something had to be done.   Mica capacitors are no longer made but fortunately new...  READ MORE
- Robert Nickels (ranickels),  03/19/2022 
   It's always a challenge to hold PC boards during assemly and testing.  After purchasing a magnetic holder from Amazon  I realized I wanted more and could easily make as many as I wanted using inexpensive 3 mm hardware from eBay and some strong "fridge magnets".     All that's needed is to epoxy a standoff to the magnet - both tapped and threaded ...  READ MORE
- Robert Nickels (ranickels),  03/09/2022 
   The Si5351 has been the biggest boon to homebrewers since the invention of the NE-602, especially now that quartz crystals are essentially obsolete.   But it's redundant to run the output of the 5351 through a johnson counter to develop the quadrature signals required for QSD/QSE SDR front-ends when there are three clock outputs available and the IC allows for phase offsets. &nb...  READ MORE
- Robert Nickels (ranickels),  03/09/2022 
   It's pretty well accepted that the Pacemaker was not EF Johnson's finest effort.   In fact it was the first of several failed attempts by the King of the AM Transmitters to make the transition to SSB.    In the end, it was the rise of CB popularity that kept the company viable, along with its component business, while their ham business gradually faced away. &...  READ MORE
- Robert Nickels (ranickels),  03/03/2022 
   LTC William L. Howard amassed a collection and in fact realized his dream of creating a museum that showcased the Army's technical intelligence operations - and a lot more.  The following excerpt was written by Col. Howard and Todd KA1KAQ:William L HowardI first got interested in radio while a Cub Scout back in 1954. I built the crystal radio set and the one tube set with help from an ama...  READ MORE
- Robert Nickels (ranickels),  02/18/2022 

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