60 Meter homemade transceiver

In Holland we got access to 60 Meter We can use 5.350 to 5.450.
The band looks interesting. I have IC-718 that can be used at 60 meter.
It works fine.

I prefer homemade radio's so I have started to build a 60 meter Transceiver.
Desired specs:
-SSB CW
-8 MHz IF
-50 Watts output
-Controlled by a micro controller.
-DDS as LO. Maybe a cleanup PLL.

Concept is to use a SSB filter in one direction. In front this filter a mixer is placed. After the filter an IF amplifier is placed followed by another mixer.
The role of the mixers depend on RX or TX. The LO switches between 8 MHz and 13.350-13450 MHZ. If one of the mixers LO is 8 MHz ,the other gets 13.4 a LO.

This is the heart of the transceiver. It contains 2 mixers, the Xtal filter, IF amplifier and AGC amplifier, and  Two 5.4 MHz band bass filters.

This is the oscillator board. It contains a 8 MHz oscillator including amplifier and filter.
The amplifier for the 13.350 13.450 DDS signal is not ready. Only the low pass filter is build.

This is the box that I plan to use. It came from another transceiver project but that did not fit in.

Rotary encoder

I bought a COPAL rotary encoder on Ebay. This encoder is used in several Japanese transceivers. It uses magnets instead of switches. It is an expensive part.

Now it is installed in the transceiver. It works fine. Only a small hardware change was needed.
I do need a better spinner for it. Unfortunately those things  are expensive too.

Some planned software updates:
Tuning is faster now. It can be improved  even mode by improving the software. It takes too much time to update the frequency after each change. An solution can be to limit the frequency  updates while spinning the knob fast.

Changing band is also done by turning the knob. It is too touchy now. The encoder produces more pulsed per rotation than the previous one. Apart from that it has no clickes. It can be solved by counting the pulses. Band chang  is done after for example 100 pulses.

home made HF transceiver continued

I worked on the homemade HF transceiver.
When connecting an antenna I heard noise increase. However on the higher bands I needed to open the volume fully to hear it. Weak stations were hard to copy.
So I build a preamp. It is placed after the band filters. Before the first mixer.
I used the following amplifier as base http://www.hamlan.org/tech/w7iuvpreamp/
Difference is that I use a 2N2219. I use relays to bypass the filter when needed.
I get 12 db gain out of it when terminated with 50 Ohm. That is enough for most bands. For 12 and 10 meter It is probably enough. I need to wait for weak signals to appear.
I have tried it on 40 meter. No signs of intermodulation.

This is close up of the panel. The awful stickers will be replaced soon.

HF homemade transceiver

I worked on the HF homemade transceiver.  See my separate blog about this project

It is now in a usable state. Still a lot of work has to be done before it is finished.
I had a few contacts with it in SSB and CW. The signal was also received by various reversed beacon receivers. I am happy with that.

As mentioned before it needs more work.
Some of the open issues are:

• Improve power output. It should be the same on all bands. The driver needs improvements and some LPF's
• Calibrate frequency. The displayed frequency is at least 10 KHz off. It could be frequency dependent. 
• Changing from TX to RX takes to long (1-2 seconds). AGC voltage is at maximum after a TX-RX switch. This is strange it must be checked.
• The filter that is used for passband tuning is too narrow.

80 /20 MHz transceiver fan problem audio problem

I have decided to make the transceiver for 80 meter only. I may reconsider but I don't want to spend too much time on this radio
I intend to use it as a signals source for experiments with IRF510 based amplifier for 80 meter.

The power amplifier need some cooling. I have some PC fans that should be usable. They work great but they introduce hum in the audio. It comes via the power supply. No problem was seen when the fan was powered from outside the enclosure. Even when using the same power supply. Getting the fan power from within the radio causes a big hum. Adding capacitors does not help. I don't understand this.

One of the problems with this radio is that the audio is low in volume. So I have added an additional preamp. It works audio is at an acceptable level. I would like a bit more but it is Ok for now.
Unfortunately

My 20Ampere power supply has a problem. Once in a while it is not 13.8 V as it should be but 18+ V instead. That power is then stable at 18V for a while. Unfortunately this broke the audio PA. Smoke can out of it,

80/20 mhz transceiver

I found out what the reason was for the bad carrier suppression at 20 meter. The problem is the sideband oscillator.  I did not have the xtal for usb. so I have use a 27 MHz  on its fundamental frequency of 9 MHz. I had to make provisions to tune it to the right frequency. That worked but the signal shape is not a nice sine wave. This causes bad suppression of the carrier.
I will make an separate sideband oscillator with some filtering. That should fix the problem.

I have made an enclosure for the radiomyself. Using some laminated wooden furniture plate and some PCB plates. A picture will follow soon.
A metal case would look better but I don't want to spend too much money on this radio . However it is retro style. That suits the radio fine.

I will make a separate box with a PLL synthesizer to improve the stability. The PLL is working. It was leftover from another project. I need to make a  controller for it using a microcontroller.

CHN 80-20 tranceiver continued

I fixed the problem with the RIT. It was wired incorrectly.

The TX/Rx leds now work for both 80 and 20 meter. These too were wired incorrectly.

Somehow I made shortcircuit somewhere. This blew a BD137 power transistor.
Fortunately I had a few more in the junk box.

At 80 meters I was able to get a bit more than 10 Watts CW. SSB however was at 3 Watt max.
I have checked all circuits. They seem ok. I fixed it by making a small mar 4 based amplifier. Now I get 10 Watt PEP out. Current is 3 Ampere at 13.8 Volt

On 20 meter it does not work that well. Output is 3 Watt PEP. The input signal is according to spec.
Looking at the signal levels in the PA module it seems that I cannot input more signal.
More signal will cause an distorted output signal. It should be possible to get 10 watts at 20 meter though. I have another power module without transistors. I will try 27 MHZ transistors instead of the BD137. I hope that does the trick.

One of the remaining problems is the enclosure. I need to make a cover for the top left right and the bottom. I hope I can get some aluminum cheap.