Friday, December 18, 2015

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.

Sunday, December 13, 2015

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.