RAN Technology

Four Channel Oscillator board


Crystal Replacement 0 Comments 12/08/2018 

One board, up to four frequencies

Posted By: Robert Nickels (ranickels)

Epson programmable oscillators are a good substitute for quartz crystals in many applications, but they're a bit different to use.   First, they are active devices that require DC power, typically 5 volts at 45mA.    Second, like all ICs they are easily damaged by static and voltages that exceed the design limits.   Finally they are in DIP packates that are intended to PC mounting, not hand wiring.

The original four-channel board is a 2" square PCB that addresses these needs by providing sockets for up to 4 Epson oscillators, a voltage regulator that works on any DC voltage from 8 to 20 volts, and proper buffering of all control and output signals so that if excessive voltage is inadvertently applied, a 25 cent IC is all that's damaged.    Buffering also makes it possilbe to select one of the four frequencies with a logic "low" or a contact closure to ground to facilitate interfacing with existing circuits.

In the old days crystals were a few dollars each, but in recent years before International Crystal closed it's doors, the price of a custom one-off crystal had risen to over $40.    The cost of the Four Channel Oscillator board plus four Epson oscillators is less than the cost of a single crystal!   The accuracy and stability is equally good at 50ppm.   Any desired frequency can be obtained in just a few days time from DigiKey, the US authorized distributor for Epson's programmable oscillator products.   These items are "value-added", meaning they must go through DigiKeys's programming department before shipment,, but don't worry - they always have a good stock on hand.    The price is $4.10 for an oscillator programmed to any desired frequency between 1 and 125 MHz, truly a modern-day bargain!


  

Mystery Transmitter

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 I didn't set out to buy this homebrew CW transmitter, it was included in an auction lot that I wanted so I had to take it to get the desired item.   But even though I always like to see good quality homebrew gear, this one is just a mystery.Most of the transmitter, including 6CL6 oscillator and buffer stages and a 6146 PA are built on a sub-chassis that is clearly part of a com...  READ MORE
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The Vector VR-50

last gasp from Swan/Atlas founder Herb Johnson
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 Most hams are aware that Herb Johnson W6QKI founded Swan in Benson Arizona to make single-band SSB transceivers and then moved his operation to Oceanside CA where Swan thrived throughout the 1960s.   Swan merged with Cubic Corporation in 1967, and Johnson managed Swan as its subsidiary until 1973. Johnson founded Atlas Radio in 1974, with the assistance of Southcom International fo...  READ MORE
- Robert Nickels (ranickels),  07/12/2021 
   The Harvey-Wells Company was formed through a partnership between Clifford Harvey W1RF, and John Wells W1ZD in 1939.   Cliff Harvey had earlier founded Harvey Radio Labs in 1933, and prior to that, he was associated with the Hendricks and Harvey Company, another partnership. Producing police radios, transceivers, transmitters, and crystals. Their most popular product was the TBS-50 trans...  READ MORE
- Robert Nickels (ranickels),  06/18/2021 
    I became aware of a few hams playing with a thing designed to receive digital TV in Europe on your laptop - a little plug-in dongle that used an RTL-2832 IC and sold for $20 or so.    Some clever fellows had determined that it could be put into "radio mode" in which it would generate an IQ stream over USB, and by writing to control registers in the tuner IC, it could...  READ MORE
- Robert Nickels (ranickels),  06/13/2021 
    A while back I acquired a six channel HF transceiver made by the Radio Industries division of Hallicrafters, probably in the 1960s, called an SBT-20.    It is capable of 20 watts SSB or 5 watts AM (or CW with an optional board) in the range of 2-12 MHz and thus was probably aimed at commercial and light-duty military applications.   The radio could by ordered with fu...  READ MORE
- Robert Nickels (ranickels),  06/07/2021 
    I'm always thinking about interesting combinations of equipment to try out on the air.   One day while rearranging the shack I was getting ready to connect my Globe Scout Deluxe back up with a Collins 51S-1 receiver when the LED (the energy-efficient version of the old light bulb) came on.When I first started playing with DVB-T dongles back in 2012 I wanted an upconverter so I ...  READ MORE
- Robert Nickels (ranickels),  05/29/2021 
  

6AG7-6LG Novice Transmitter

Classic circuit with some modern twists
Category: Vintage Ham Radio
 There's a good chance that more homebrew ham transmitters have been built using a 6L6 than any other tube, and when combined with the superior performance of the 6AG7 oscillator, it's a hard combination to beat (click here for an explanation of the 6AG7's benefits)I'll be adding more info about this project soon, but one of my goals was to reproduce what was a budget-friendly...  READ MORE
- Robert Nickels (ranickels),  05/21/2021 
    All who operate AM in the midwest know and probably have talked to Masa, AB9MQ, who is a very active AM operator.    Having become interested in ham radio while still living in Japan in the early 1960s,  Masa's memories of the "dream rigs" is a bit differen than most US hams, and because the markets were still quite regional at the time, much of the ham gear...  READ MORE
- Robert Nickels (ranickels),  05/18/2021 
  

Hudson American Corporation

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 I enjoy playing with old marine radios that operated in the AM mode between 2-3 MHz.    This was the standard for "ship to shore" radio and telephone service from marine radio operators from after WWII until about 1970 when SSB was phased in and AM became obsolete.     Through this era a number of manufacturers were major players including RCA (Ra...  READ MORE
- Robert Nickels (ranickels),  05/02/2021 
    I've always thought that knurled aluminum knobs were a high-class option for radio gear, and while they are more durable than plastic they do accumulate tarnish, corrosion, and grunge from dirty fingers over the years and start to look poor.   Fortunately it is easy to restore them to a new attractive appearance using a bead blaster. Mine is a Harbor Freight floor-standing...  READ MORE
- Robert Nickels (ranickels),  04/29/2021 

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