status update

I have just build some of the components in the box.
The transverter/cb radio can now receive 160-10 meter. It can also transmit a tiny signal.

Multiband HAM to CB transverter

This is the starting point of the multiband HF to CB transverter.
The shown setup actually receives pretty well. I have tested it on 160,80 and 40. The other bands are closed during the night.

The components are:
-CB transceiver. It is modified it has 0.1 Milli Watt output.
-SDR kits VFO using si570.
-A bandpass filter for 160 to 10. Made in Russia, bought on Ebay.
-A HPF-501 mixer and a amplifier using a bfy 90. Using the same concept as my 40 meter to CB transverter.

That is enough to build a converter to CB. It should be able to transmit as well but I have not tried transmitting yet. It will probably put out 0.05 milli Watt.

I have a 5 Watt amplifier kit for 10 to 160 meter. This PA comes from box73 hamradio. I want to use it to amplify the signal to QRP level. The output of the transverter can not drive this amplifier so I need a small amplifier. I may use a MAR amplifier.

The PA kit does not include a heatsink so I will search the internet to get one.
Maybe the local electronic shops have a suitable one but I doubt it.

Lowpass filters are needed to filter the signal out ofthe PA. I already have one. Just another ebay purchase. It was part of a 100 watt HAM band transceiver so it should be suitable for my project. A picture of it will be posted soon.

One of the other projects I am working on is a QRP HF transceiver. I will combine both projects. After all only the LO and The IF frequency are different in those projects. The CB radio will be used on a fixed channel. The IF strip of the QRP transceiver uses 9 MHz. The SDR kits vfo can be setup for another IF offset by pressing a few buttons. It is a piece of cake.

USB synthesizer 2

Last night I finished building the USB synthesizer. Fortunately it worked the first time I turned it on. It works from 3.5 MHz to 180 MHz so I can generate all frequencies I need.

On ebay I bought a bandpass filter unit that has filters for 10-160 meter. That would be ideal for the CB to all HF band transverter.

I am considering to continue in a different blog. This blog is for the simple CB to 40 meter transverter. The new blog will be dedicated to the all band to CB transverter.

High IF

The high shortwave bands 24 and 28 MHz are difficult when using 27 MHz as IF.
I am considering to build a simple transverter to a high frequency. I can be made similar to the one described in this blog.

The 27 MHz trx transverter combo can be used as IF for the shortwave transverters.

50 MHz could be used as IF. All I need is a 23 MHz xtal, a mixer and some filters.
A preamp may be needed as well .This way I have a 50 MHz radio too.

A better option is to build a transverter to 70 MHz. Currently PA land does not have an 70 MHz Ham allocation. This may change in the future though. 70 MHz Is a better IF than 50 MHz. Besides, SAW filters are available for this frequency. Those could be used as roofing filter.

A lot of conversion is done in this concept. The SSB signal will surely degrade by those conversions. It should be possible though after all some ham radio's use 4 conversion too.

USB synthesizer

At the annual radio market in Rosmalen I bought a USB synthesizer kit.
See SDR-KITS
It uses the si570 to generate signal between 3.5 MHz and 180 MHz.
This unit can provide all frequencies I need for the all-band version.

Power output is a bit low. I will amplify it using a MAR amplifier. That should not be a problem.

The synthesizer is USB controlled. I will use a PC to control it. I might add a micro controller board later.
However, I am considering to make it a PC controllable Transverter.
To do that I need some USB controllable I/O ports. I could even make a PC controllable transceiver.

The power amplifier I will use is 5 Watt amp box73 it is a 5 watt amplifier that works from 1.8 to 144 MHz. So I can even add 50 Mhz an 144 MHz.

More design considerations later.

allband version

I have investigated the possibility to build an allband version.

A device Si570 could be used to generate all signals. The CB set can be set to a fixed frequency. A microcontroller, LCD and rotary encoder can be used to control the Si570.

It should be possible to build one for most HF bands. However 28 MHz will be difficult. The Mixer will leak some 27 MHz. A suppression of 40 db is possible but it is hard to accieve. The 28 MHz bandpass filter won't provide enough attenuation.
I think that 24 MHz will be difficult too.

For 14 MHz and higher a preamp between the mixer and the bandfilter may be needed for reception.

Using a Lo signal that is higher than the reception frequency is needed for bands > 10 MHz. LSB and USB will be switched. I better use it for all bands. it will reduce software complexity. An additional advantage is that the Lowpass filters can be used to reduce mirror image reception.

80 meter version

The design can be adapted to 80 Meter. making a suitable LO signal may be a bit difficult though.

Two 23.5 MHz xtals are required (27-3.5). These are non standard as far as I know. 30.5 (27+3.5) MHz can be used instead. Those are nonstandard frequencies too.
using 30.5 inverts LSB and USB.

23.5 MHz can be generated by dividing 47 MHz by 2. You could try to use a VXO at 20 MHz. Then double this signal and mix it with 7 MHz.

A band 300 KHz wide band filter for 80 meter can be found in the Elecraft K2 design.