Current state

Al but one modules are ready. Only the amplifier driver for the PA is not build.
Most other modules are functional but need some work.

PA
This module was a kit from box73.  It seems to work fine.

LPF module
The band filers for all bands but one (28 MHz) are working the way they should. I may be able to increase harmonic suppression but they harmonics are below the legal limit. So no immediate need.
The 28 MHz filter is not OK.  The harmonic suppression is not good enough. On 56 MHz only 30 db suppression was measured. As a temporary fix I have added a series LC circuit that short circuits the 56 MHZ signal. It works but it reduces power to 3watt.

IF strip
I use two xtal filters. One of them is used for passband tuning. Both filteres were not OK.
The one that is used to make the ssb signbal out of a dsb signal was very bad. It was very wide and it has a high attenuation. It turned out that one of the xtals was too far off frequency. This filter is now working Ok. It was needed tom measure all xtals and select the ones that have the smallest  frequency difference.
The other xtal filter is a bit too narrow. I have bypassed it temporary.

TX/RX mixer and noise blanker.
This module contains the following items:

• The TX/RX mixer . This is a HPF505 diode mixer similar to the SBL1
• Amplifier for the DDS LO. It should have the same ampliufication from 1.6+9 to 29+9 MHz. It took some fiddling with capacitor get it right but it works ok now.
• Noiseblanker. This concept was 'borrowed' from the elecraft  K2 design. It worked badly but I used different transitors and some other components. After some adaptions the noise detection works. I still have to see how it performs in practice.

Bandpass filter:
I did not use the filter from the Ukraine after all. I made a new one.  It works Ok but at some bands the bandwidth  is a bit too small. For receiving this is no big deal. I suppose A few db's  will not be noticable.  For transmitting it is not acceptable. Power output should be the same over the whole band. The amplifier/driver should solve this. This has to be done.

Speech compressor/clipper.
This is base on a design of PA0FRI. It is a double sideband clipper. I had some problems making it work. First off all the oscillator did not start. I fixed it by changing capacitor values.
Then I had to fiddle with the clipping. It worked but the output was not symmetrical.
After I got all issues fixed I was quite happy with the performance. The signal sounded OK when I monitored it using a PC speaker. Not really HIFI but usable. When I used it as audio source for the IF strip the resulting ssb sounded pretty good. 

Driver for the PA
This module has yet to be build.
It is complicated. As the signal levels out of the band filters can vary I have to use variable gain. The output level should be the same for all bands.  I think I can do it by using a detector to measure the output signal level and feed back this DC signal to a amplifier that has variable gain. This way the input level can vary while the output level remains at a fixed level.
I will use the 1350p IF amplifier for this.








  

Building it all together

Most modules are ready. Now it is time for the boring stuff like drilling holes.
Picture below shows the frontpanel.

Next picture shows most modules mounted. Wiring is also shown
On the right is the IF strip
The middle one is the bandfilter module.
On top is the TX/RX mixer and the noiseblanker.
PCB on the bottom is the relay module that switches TX/RX ,LSB/USB .
The other PCB contains the CW sidetone generator.

Next picture shows the backside. It contains the PA an the Lowwpass filters.

Microcontrolller work

May daily jobs involves programming small processors. So I don't want to program at home.
However the transceiver requires a microcontroller so I did some programming anyway.

Stuff I use
-PIC 16F877 microcontroller running at 20 MHz.
-rotary encoder, LCD and several switches.
-2 x 74164 shift registers to select the band. No more IO pins were available.

Features so far:
-Tune the HF band an 160 Meter. The DDS is used as the LO.
-Basic RIT functionality
-Band selection By pushing a button and rotating the encoder. Band is outputted using the shift registers. They drive a relays using a transistor.
-Mode selection LSB,USB and CW by pushing a button an rotating the encoder. An mode dependent offset is added to the DDS frequency.

Features to implement.
-TX and RX handling like adding RIT offset while receiving. Maybe TX/RX in display.

In this state the controller and DDS should already be usable. I have not used it as a LO yet. I have to make an amplifier and a filter for the DDS output first. The frequencies out of the DDS seem OK.

Now I am working on the lowpass filters.

Some progress

Progress is slow on this one. Besides  did not update this blog regularly.

I did a few things though.
-If strip is working. But it needs some finishing touches, like using varicaps instead of trimmers for the band pass tuning.

-I found an enclosure for it. I bought it from a ham who was quitting the hobby.

-On  ebay I have found cheap AD9850 dds modules. I have bought a few. One of them will be used as synthesize for this project. I know that it is not ideal with respect to phase noise. I can add cleanup oscillators later.












I made a controller for this board using a PIC processor. Now I can generate signals between 0 and 40 MHz

A band pass filter is almost ready. I had top skip 160 meters as it did not fit in the filter enclosure (tin box).

 
 

progress on IF strip

In the last couple of days I added the following features:
-CW TX support.
-AGC fast and slow.
-Noise blanker. It does not include the noise detection though. That will be a separate module. I have to experiment a bit to get a adequate blank pulse.

The CW sidetone may not fit on this module. I could keep the receiver on during CW transmission. That will generate a sideone. I do fear that the receiver will overload though. Maybe I can reduce sensitivity during TX.

Band filter

This is a band filter for 160 to 10 meter. I bought it on Ebay to save time. It saves money too.
It came from the Ukraine. I hope it works as expected.

IF strip

This is the IF strip. Development is still going on. In this stage it can generate a SSB signal.
It can also demodulate SSB. The audio amplifier is working and so is the variable bandwidth IF .
Things to add:
-AGC functionality.
-Noise blanker.
-CW sidetone.
-CW TX support.
Adding a noise blanker will be difficult because of lack of space. The blanker itself will fit. The noise detector may not. I could add a separate noise detector module in another tin box. 

I plan to draw a schematic diagram of it.