Tuesday, December 21, 2010

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.

Thursday, December 16, 2010

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.

Sunday, December 5, 2010

Start of blog

In this blog I will describe the designing and building of a HF (QRP) transceiver.
I have already build one some years ago. Now I will try to build a better one.

Next picture shows the old one.

 Some of the features:
-Triple loop pll synthesizer,. 30 Hz steps.
-Controlled by micro controller pic16F84.
-Covers 500 KHz on 80 40 30 20 17 15 12 and 28 MHz.
-Modes usb, lsb, cw
-CW audio filter.
-Power output 8 Watt PEP on 80 meter, 3 Watt  PEP on 10 meter. Power is adjustable.
-AGC 1 speed.
-CW side tone

The new one should have extra features like.
-5 Watt PEP on all bands.
-Coverage of all HF bands including 160 meter.
-Adjustable IF Width.
-RIT.
-Noise blanker for pulse noise.
-Internal power supply.
-AGC different for CW and SSB.