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An Archive of Useful Modifications to SGC Equipment
Modification of radios has been a tradition in the HF community.
In many cases, modifications can provide desired functionaliy for uses unforeseen or not intended to be addressed by the original manufacturer. 
Some of the mods shown on this page are not approved by the manufacturer.
Information provided for educational use only. No liability assumed.
In some cases, modifications of internal circuitry may void a manufacturer warranty.
Some of these modifications have been designed by Amateur Radio or radio  experimenters. 
SG-2020 Mods
General Coverage "Export" Frequency Mod
Heil Microphone Element Mod
CW Thump Filter (external)
SG2020 Bottom View With Cover Removed

A. SG-2020 General Coverage Transmit Frequency Mod 
Enables transmit from 1.6 through 30MHz
Photo shows front panel circuit board and 4 pin cable connector unplugged for access to "Export" jumper.
SG2020 Front Panel PC Board With Export Jumper
1. Disconnect power, remove 3 screws from bottom, and remove enclosure by sliding chassis out.
2. Unplug 4 pin connector from front panel PC Board behind knob.
3.  Using a very small diagonal wire cutter, cut the wire jumper between the black encoder and the 4 pin connector on the front panel PC Board..
4. Plug in 4 pin connector and re-assemble chassis in enclosure.
5. Observe authorized frequency liimits.

B. SG-2020 Heil Microphone Element Mod 
Changes the stock dynamic microphone element and modifies the internal microphone circuit to operate with the Heil crystal element for more audio "punch".
Photo shows R25 changed from 100k to 220k for more gain and R28 changed from 2.7k to 5.6k 
to match Heil crystal microphone element.
SG2020 Microphone Amplifier and VOGAD Circuit
1. Disconnect power, remove 3 screws from bottom, and remove enclosure by sliding chassis out.
2. Unscrew 3 screws with 2 spacers, and carefully remove sheild plate at position B shown in 1st photo of bottom of PC Board. 
3. Using a soldering iron and tweezers, carefully remove R25 (100k) and solder in its place a 220k type 0805 resistor.
4. Remove R28 (2.7k) and replace with 5.6k type 0805 resistor.
5. Re-install sheild plate, spacers, 3 screws.
6. Re-assemble chassis in enclosure. 
7. Dis-assemble microphone case, de-solder leads from microphone element, and remove element.
8. Install the Heil microphone element using supplied foam spacers to hold it in place.
9. Carefully solder the microphone leads to the Heil element contacts.
10. Re-assemble microphone case.

C. SG-2020 External CW Thump Filter for Headphones 
Alleviates Audio Thumping in CW Mode
Drawing shows series LC filter of 330uH inductor, 
10uF capacitor, with stereo mini input and output.
1. Procure parts: 
Stereo mini jack and plug. 330uH inductor. 10uF capacitor. Wire and enclosure for mounting parts and stereo jack. 2 conductor cord for plug.
2. Mount stereo jack, run cord through hole in enclosure, solder plug and parts inside enclosure according to schematic.
3. Plug into speaker jack of 2020.
4.  Plug headphones into Thump Filter jack.
5. Use of filter in SSB mode not suggested.
Do you know of a useful modification for SG equipment?
Your comments and contributions are welcome on the SGCgear email list.
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