80 meters (80m) AM on a CB Radio PART 2 - No Modification needed

[bob4analog]

This is great! I do hope you'll post the schematic of the circuit sometime. Would love to build it.

73,

Bob, KD5MHQ

[emwavemhz]

This is a good way to build up a homebrew rig. One could take a SSB/AM CB fix it to one channel. Reconstruct into a new cabinet and add a converter with a VFO and amplifier. One good use would be for 2 meter SSB at 144.200 MHZ or other VHF/UHF or microwave frequencies. Using the CB rig as an RX/TX IF module would simplify the work and provide good performance. With some work the face plate could look professional and be a cool rig!

[G0OMH]

Great job, keep up the good work.

73 Peter.

[uploadJ]

Nice! I've had this idea kicking around in the old noggin for awhile too!

.

[2e1dxy]

Nice one! I had one of these radios back in 1981 when i was 14!

[HPDpvtcaboose]

am is that a different frequency to uhf cb radio or some cause im getting my friend a radio a mobile one for his house im on a uhf if i get a am i wonder if i can still hear myself i wanna know before his birthday thuesday

[emerald48]

@HPDpvtcaboose no they are not the same. UHF is on completely different frequencies to 27 MHz CB. AM is an old modulation mode originally used for CB which is still used in USA and some parts of Europe, but FM is technically superior, with better signal to noise performance and less interference.

[51nw]

@HPDpvtcaboose  HAM RADIO SUX!

[HPDpvtcaboose]

@51nw i didnt mention ham radio 

[bob4analog]

...Why???

[K9FON]

Aside from the CB micreant comments, the old rigs that were made back in the 1970s will hold up better than anything made today. Thats why i am keeping my old Cobra CB rigs i got years ago.

[emerald48]

@K9FON Yes I think the old cobras were exceptionally good and a rare breed. More basic radio's weren't so good really. People still have great affection for them (including me) but in reality I can use my Maycom within tens of feet of another station without even knowing they are there. Old AM rigs like the one in the video suffer from bleedover, rx blocking and poor signal to noise performance, but I still have much affection for them and like to use them.

[CBRADIOLOVER]

Mayn thats a big ole waste of a good radio, probably the best youd ever hear ham crap though, cb is way better an far more profesional then hams are.

[emerald48]

@CBRADIOLOVER - I understand your enthusiasm for CB but even as a CB'er I still find these types of comment a bit ignorant!!. CB's like the one in the video sound nice on air but really have quite poor technical performance out of the box, mainly on the receive side. Amatuer gear is way superior which is why so many CB dx'ers are using Alincos and Icoms on CB.

[OH2FFY]

Yeup thats one way to do it.

TXverters are still used in microwave applications but aren't used on HF anymore.

At one time long ago though they were a popular way of giving a radio extended band coverage.

But its pretty well a dead idea now.

It is however interesting on a technical and experimental level.

Regards

gregW:-) OH2FFY

**See my Ham Radio videos on YouTube**

[OH2FFY]

Hi

Converters that can also transmit are called transverters.

They are a lot harder to make than a simple RX mixer as they have a full PA section and filters for the new frequency.

Currently I am modifying a CB radio to operate on the 20 meter ham band.

It should be finished in a couple of months and I will be putting up video's of it on Youtube.

The Yahoo group CB2HAM has quite a few people interested in modifying old CBs to operate on the ham bands.

Regards

gregW:-) OH2FFY

[emerald48]

Thanks for your comment Greg. My converter uses a double balanced, high level diode mixer that I found in my junk (from an old SSB CB radio I think), and a tuned filter for 3.7 MHz.

Transmit is theoretically easy to accomplish because the mixer works in reverse too,. By transmitting straight back into the same IF pin via an attenuator to 10mW, it should already transmit about 2 to 3mW on 3.7 MHz. I expect three stages of simple class A linear amplification and a LPF would give 2 - 5 watts.