60 meter transceiver amplifier and agc

The unit that provides 5 mili watt on 8 MHz and 13.350 -13.450 MHz is working. It is connected to the main board. The 13 MHz signal comes out of a signal generator. Later the signal generator will be replaced by a DDS board.

On the main board I have build the amplifier for the tiny 5.4 MHz signal out of the mixer. I can get 5-10 milli Watt out of it. That is enough for now.
In receive mode I can get 8V pp audio with 2 uV 5.4 MHz signal input. This signal is rectified and used for the AGC. It works, from 2uV to 30 mV the signal level of the audio is constant. I cannot get more than 30 mV from the generator.
The time constants for the AGC must be improved though. I want fast attack and slow release.
So some more experiments are. needed.

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.