As I posted earlier, someone has wandered on my blog in trying to find out “how to build your own sputnik transmitter”. Well first thing is to define Sputnik Transmitter.
The original transmitted on 20.005 and 40.002 MHz. The problem is neither of those are on an internationally accepted amateur radio frequency. If you are going to build one and are not a member of the government, it needs to be on an amateur radio band. The Soviets did not have worry about that in 1957. But an enthusiast in 2010 does. So lets determine the new frequencies.
Instead of 20.005 MHz, we will choose the next closest amatuer radio band. It is the 15 meter band. It is from 21.000 to 21.450 MHz in the USA. Since Sputnik I just transmitted a carrier, we should keep it in the CW range. Hence 21.00 to 21.200 MHz.
Now we need a transmitter for that. Sputnik was just a watt. With modern equipment we have lots of choices. Look at the QRP radios. MFJ makes one at 1 watts:
It, MFJ 9315K, is one watt and only $99. I would suggest replacing the variable tuning with fixed value a capacitor if you are going to launch it.
There are multitudes other radios to use and kits to use for the 15 meter CW band.
The other frequency was 40.002 MHz. We will need to deviate from it significantly. We need to go to the 6 meter meter band. In the USA, it is 50 to 54 MHz. The dedicated CW portion is 50.000 to 50.100 MHz. Again, MFJ can help you:
The MFJ 9406X is a bit more pricey at $289. But then, the Soviets spent way more and the US wished they had too.
There are alternatives. The Yaesu FT-817ND will suffice nicely for both. You might be able to to get by with just one. Sputnik transmitted on 20.005 MHz for 0.3 seconds and then on 40.002 MHz for 0.3 second. Repeat for 22 days. The Yaseu FT-817ND can be computer controlled. It has two antenna outputs so you can use two antennas just like Sputnik. I am not sure if you can switch that quickly. Hence you might need two FT-817NDs or one FT-817ND and one VX-7R. The VX-7R will transmit AM on the 6 meter band at one watt. Just don’t feed the mic with audio and you have CW.
There are multitudes of radios and circuits you can use. Once you settle on your radio design (kit, homebrew or two transceivers), you need a control circuit. Sputnik, as mentioned earlier, alternated between the two frequencies. If you don’t want to go farther into emulating Sputnik, a 555 timer and driver circuitry will do nicely.
However, Sputnik did more than transmit carriers on 20 and 40 MHz. It also varied the timing of the pulses in relationship to internal temperature and pressure. So you need to measure both. Omega makes a nice serial addressable probe. Combine that with a basic stamp and you can control your home made Sputnik.
Now you got the transmitter, you need the rest. Sputnik was a 23 inch aluminum sphere. Church Metal has 24″ hemispheres available. Now you need two antennas. Just use some wire rods and a tuner for each band. The original were two 7.9 ft rods and 9.5 ft rods.
The original Sputnik weighed 184 pound of which 110 was batteries. Our transmitter is very light and with lithium or NiMH batteries, we can easily get below that weight.
Or you could just build a model. Get two of these:
Cut the bead off and glue/braze some brazing rods on to get this:
BTW, polish the hell out of it.