Grundig "GS350DL" Field Radio Analog VFO with AM/SW frequency lock.
Grundig Radio Line By Eton http://www.etoncorp.com/ This is just a cool idea and an idea for a customized gift for someone. I had an idea for this radio, based on the notion that one day they make the analog VFO stable or lockable. Well they did just that. I had a version of this radio I got for $60.00 on sale. And liked it, but the analog VFO drifted. However it has that nice Grundig radio sound to it. Ok, I realize that the lock system they may now be using may have some VCO phase noise. However this is a broadcast receiver and would only be used for occasional sideband uses with SDR software. Most people would use it for shortwave listening to broadcast stations. And for DRM use. So I would still use it with a QSD section home brewed and installed. I do know that the inside has allot of room for added circuit boards. And it already has a stereo line level output that can be used with the PC sound card, so that can be used for convenience. It also has a external antenna jack. And if you did use it for a SDR set up, you can unplug the radio and take it outside as a portable radio any time you wanted. Well an enterprising soul could fix this up and then give it as a gift to some young soul interested in radio, someone like grandpa could fix up the grandchild a cool radio. It looks cool also. Features AM (530-1710 kHz), FM (88-108 MHz) and Shortwave continuous coverage from 3 to 28 MHz. This includes 13 international broadcast bands. (11, 13, 15, 16, 19, 22, 25, 31, 41, 49, 60, 75 and 90 meters) Highly sensitive and selective analog tuner circuitry with AM/SW frequency lock Rotary volume control Main tuning knob and independent fine-tuning control knob Variable RF gain control Digital frequency readout Liquid Crystal Display, LCD Selectable 12 or 24 hour clock display format with alarm, sleep timer Stereo line level audio output Input for AC adapter I imagine that if you got a circuit diagram of the frequency lock section, it could be improved for lower noise. I would use a 10,000 uF cap across the AC Adapter input as a start to filter out AC line noise, and use allot of ceramic decoupling caps to filter out noise in as many places in the circuits as possible. Especially around the VFO and frequency lock section. Some noise may come off of the LCD so it needs a decoupling cap across its V+ power supply input. And enough line level audio cable to separate it a good distance away from the PC monitor. A switch to turn of the AGC would be useful for SDR. ka9rza
