GCR2 Transceiver

General Coverage Mini R2 Receiver Incorporated Into A Transceiver


The Preselector Circuit

The "Almost Completed" Receiver

The following photos are of the completed RX stages. I mounted the DDS I/Q VFO on the top of the chasis partition alongside the preselector. The Mini R2 and filter board are mounted on the bottom. The boards are stacked with the filter board on the bottom. The filter board has three optional filters that are selected by a rotary switch on the front panel: 1kHz, 3kHz elliptical, and what KK7B calls "SSB Wide" which is actually the receiver wide open with a simple attenuator to control the gain. The extra standoffs are for the three transmitter boards: RF Amp, T/R Circuitry and Lowpass Filters (none of which are installed in these photos). The receiver, as presented here, is playing very well from 1.8MHz through 30MHz. Things to solve at this stage: I am hearing very faint noise when the encoder is turned and am hearing RF interference from the LCD backlight (not wideband noise, only on certain frequencies).

The Front Panel

Below is a photo of the front panel which shows the templates I made for the LCD and the 24 switch pushbutton array, both for the DDS I/Q VFO. Both templates are made of fairly stiff aluminum. One suggestion that I have, if the builder of the VFO wants to use the supplied PCB board for the switches (which is very nice) is to replace the supplied switches with ones with longer buttons. The ones supplied are very short and will not protrude through any template very far, making entry keying difficult. I simply bought the same model of switch but with a longer button from Digikey.

The controls on the front panel thus far are: Preselector Switch (top left), Preselector Vernier Drive (top left), Pushbutton Array (top right), Tuning Knob (center), Phone Jack (bottom far left), Volume Control (bottom center left), Filter Switch (to the right of the volume control), and Power Switch (bottom right, with LED indicator). The line on the bottom right is to align transmitter controls, when installed, with the RX controls.

The Finished Receiver

After several days of listening, I've concluded that the GCR2 performs on a level rivaling the best receivers I have listened to. I have built a number of other Mini R2 receivers and this unit works better than any of its predecessors. Even while tuning very loud signals, the unwanted side of the signal is hardly noticeable. There have been a few component changes in the Mini R2 since I built my last one several years ago. Perhaps this accounts for the better performance. However, I think the excellent sideband rejection is the result of a very well matched output on the IQPro DDS. I carefully matched both the I and Q outputs with my oscilloscope. There were a few things I needed to tweak to satisfy my ears, however. Here are a few notes:

The photos below show the completed RX installed in its Ten Tec enclosure. As you can see, I choose to change the original vernial dial, opting instead for a reduction drive unit installed inside the cabnet. (W3TS was strongly opposed to the "cheap-looking" vernier that I originally used!!)

And finally, here's a photo of the inside of the top of the rig as it exists currently (12/12/06). This photo shows my final wire placements, and the shielded preselector.

The Transmitter
(Click this link to go to the transmitter page.)