The quickest and easiest way I have found to make a CB into a
There must be millions of the older 23 channel CBs that use the 12 crystal synthesizer set-up with a 23 MHz oscillator and 14 MHz oscillator setup. Check "Garage Sales & Flea Markets" for the bargain rigs
In this rig, the 23MHz signal mixes with the 14MHz signal to produce a signal in the 38MHz plus range for IF.
To receive, this IF 38MHz signal is mixed with the receive oscillator signal (11.730MHz) to have a signal that is 455KCs offset from the operating frequency.
Example… 23.290MHz mixes with 14.950MHz for the 38.240 frequency and then mixed with 11.730 to get 26.510MHz …. This 26.510 is .455 lower than 26.965MHz which is channel one..
To Transmit on channel 1, this 38MHz signal is mixed with the transmit oscillator signal (11.275) to have a 26.965MHz operating signal.
Another example…. For channel 23…. 23.540 mixes with 14.990 to get a 38.530MHz signal. The 38.530MHz signal is mixed with 11.275MHz for a 27.255MHz transmit signal.
Now, that's how the CB works....... Now to put it on 6 meters for a beacon.
The idea is to inject the transmit oscillator frequency tuned to the
"high side" so the 38.500MHz
IF will have the injection "added" to instead of
"subtracted" from the IF.
Now remove the receive oscillator crystal 11.730 MHz and install it in the TRANSMIT OSCILLATOR position (this also disables the receive)...See my note below
By putting in the 11.730 MHz crystal the mixing scheme for channel 23 is 38.530 MHz plus the 11.730 MHz equals 50.260 MHz........ Too high for a six meter beacon....... so switch to channel 1 and the mixing scheme will be 38.240MHz plus the 11.730 MHz equals 49.97 MHz ....... too low for six meters.......
Ah Ha! Channel 10 becomes 50.08MHz and channel 6 becomes 50.03MHz .... so Channels 7, 8 & 9 are within the beacon band
Now, on the older CB's the rig is usually "broadbanded"enough to get a little signal through...... ..Do not adjust any of the "cans" except those that "follow" the TRANSMIT OSCILLATOR to the output........ I'd first try backing the slugs all the way "out"....... (remember there is an adjustable inductor to prevent interference to TV's by CB operation)......... Identify and disable this TV interference inductor....... NOW, if worse comes to worse in regards to getting the output to 2 plus Watts.... replace the ferrite "slugs" with brass #10 or #12 machine screws
With a little capacitance added .... the crystal will "bend" a few Hertz either way. In parallel the frequency goes up ... in series, it goes down. I like to use a "trimmer" in series for frequency "tweaking"........ TINY is the word for trimming ..... certainly less than 10 pf
The CARRIER output should be about 2 Watts after the "cans" in the transmit circuit are "tweaked" .....Do not adjust any of the "cans" except those that "follow" the TRANSMIT OSCILLATOR to the output.
found that some "cans" just are too "narrow banded" to adjust easily...... and
the BRASS machine screw use will help on many of the "cans"
Currently the 6 Meter "sub-band" for beacons is considered to be 50.060 to 50.080MHz
To transmit a CW signal, a person only needs to interrupt the PTT circuit of an AM rig.
There are many ways to "key" the PTT circuit……. Any memory keyer …. Computers….
NOTE BELOW...... I'm thinking that the receive would not have to be disabled.... If the removed transmit oscillator crystal was put in the receive oscillator's place........ it would give a 455KC "offset" on the lower side of the transmit frequency.... and the addition of a simple BFO circuit would make a channelized 6 meter QRP rig........... I have not done this but I think it is feasible.
---- MEMORY KEYERS? Good Deal on the market is the "TICK 2B" at 15 dollars for the SMT kit with 25 character memory for beacon operation. Takes "close" eye work and a steady hand.
BEST DEAL...... PICOKEYER by NØXAS http://www.botkin.org/dale/pic_keyer.htm.... currently $10.95 for the Chip and Socket.......With 62 memory characters. Minimal external parts....... "bread boarded" in less than 15 minutes. (and I am not particularly fast anymore) :-)) see www.qsl.net/wj5o and click on "BEACON KEYER"
My opinions... Certainly not a commercial !...... There are many many good memory keyers available ....... Just run a "Google" search for memory keyers