The radio receives AM beautifully, and CW and SSB well enough (by tuning the regeneration control past the oscillation point). Its no problem to tune any station on the low bands (160M -40M). Its more of challenge on 20 meters. I enjoy listening to the AM broadcast band at night when stations from all over the country are easily heard. I also like to listen to 40 Meter or 160 Meter CW on one of these while tinkering at the workbench.
A good antenna is a must. My favorite receiving antennas for the GR-81 are a 40 meter dipole or a G5RV.
Listening to shortwave signals with a minimalist regenerative set is a fun experience that introduced many to the wonders of radio, including me. Of course, I spend most of my time listening to the amateur bands.
I converted a schematic and partial manual found on the web to PDF format and its quite legible. The link is here. I have recently laid hold of a complete original manual.
Dick Strippel, the author of the Old Timer's Bulletin notes the following:
"For minimum money and building time, these (regenerative) sets provided a simple and fun means to explore short wave radio. Despite a simplicity of design, their overall performance could be outstanding in the hands of a skilled operator, exceeding that of simple superhets such as the venerated Hallicrafters' S-38, and without their image problems."
"One of the last tube-type kit regens was Heathkit's GR-81 'Economy SWL Receiver' of the mid-1960s. In implementation, it stood head and shoulders above its last-of-the-breed competitors such as Knight's long-lived and continually evolving 'Ocean Hopper'."
"The Heathkit incorporates an isolation transformer for safety. The GR-81 includes bandspread and the usual volume and regeneration controls. The circuit is a very simple design, but the four-band coverage, the isolation transformer, the power supply choke, and even the fuse set it apart from other sets with similar circuits."
I certainly have enjoyed the ones I've owned. With these old radios its just a matter of time before the filter caps and the "black beauty" capacitor give out. Having restored several of these radios it should be noted that recapping the GR-81 (replacing the normally suspect capacitors) makes a significant difference in performance even if the radio receives signals with the original 1960's vintage electrolytic and black beauty caps. Recapping has solved a variety of problems in GR-81's I've owned. To really bring one of these to life, I heartily recommend replacing the electrolytic and black beauty capacitors and using a good wire antenna. Cleaning the band switch and potentiometers with DeOxit is also essential.
Most GR-81's found these days have varying degrees of fading, rust, and deep chips on the beige cabinet. Sometimes either the "Heathkit" decal on the front or the serial number decal on the back are missing. Feet are also frequently broken or missing. Also, the small knobs that came with these often warp just slightly "out of round" over time (when the set-screw is really tight), so on some of the sets, I have had to pull the slightly warped knobs 1/8 inch away from the panel, so they clear the nuts without scraping.
Here is another one I restored
This one was filthy and barely worked when I
got it. Now it works perfectly and looks pretty good too.
Notice the pointer style fine tuning knob on this one (Heath used 2 kinds of
knobs for these)
I buy old GR-81's in any condition (please don't throw it away). I can be contacted by email here.
If you need the main tuning knobs, the clear plastic frequency indicators, the fine tuning knobs, the smaller knobs
or 12AT7 tubes, I have them available.
Unfortunately, I have no restored GR-81's for sale at the present time.
More photos of another restored Heathkit GR-81.
Top View Bottom View Side View Front View
Heathkit GR-81 Parts