Inside a G6 + Review Comments


John H. Bryant <bjohnorcas@...>
 

I had hoped that a modified E6, with its reported SSB capability, could serve as a spotting receiver for my hotrodded E100 on my upcoming adventure to coastal Peru. I now don't think that I'll take it, but I did learn quite a few things while modifying the radio. I've uploaded five photos to our Photo section that will give you a peak at the inside of a G6 and see my antenna mod, as well.

http://ph.groups.yahoo.com/group/ultralightdx/photos/browse/f619

Opening the set is no problem at all... two screws on the back and one in the battery compartment. What you get is a clamshell, connected together by a ribbon cable.  The upper board with the display and control circuitry (and speaker) stays with the top and the main board with the input/output jacks to one side, stays with the bottom.  I think that the main board is held in by those input/output jacks on one side and a single screw on the other.  I'm pretty sure that the plastic fitting where the ribbon cable meets the main board is NOT a pin plug, but just a hard-wire solder fitting to permanently attach the two boards together. I also would not be surprised if the main board is also glued in the back part of the case.  What I'm hinting at is my opinion that doing a filter change on this radio would be a NIGHTMARE....  so would any other mods to the main board.

Putting an antenna pickup coil on the ferrite bar was a bit of an adventure. The bar was held in with three blobs of hot glue which came out quite easily, but prying the bar up so that it could be worked on was really tough.  It turns out that there is a blob of really tough glue under each end of the bar, too.  I'd guess that anyone would have about a 50-50 chance of breaking the bar rather than getting it out. I finally raised one end far enough to put the pickup coil around the bar.  Since I could not get to the back side of the main board to attach the coil leads to the existing antenna jack, I used a continuity tester and found metal tabs on the outside of the jack that would connect to the two parts of the antenna plug (tip and braid).... after tacking the two leads to the antenna jack, it was just a matter of buttoning things up.  

I tested the new antenna input arrangement immediately.... sitting in my shack between two computers, the radio, barefoot, was wall-to-wall buzzes, burps and just a few stations, badly QRMed. I plugged in the outside antenna and things cleared immediately.... the "swamping effect" was alive and well and I could feed MW signals directly to the G6 from outside.  Success!!!

REVIEW COMMENTS
What I did not note in my brief look yesterday afternoon was signs of massive amounts of overloading.  I should have been looking for this, given Colin Newell's comments in his current review on dxer.ca about the 6 being too sensitive for use in urban areas. I really looked forward to testing the G6 this morning at dawn, with plenty of Asian split frequency stations, some that would be running S-8 or so. Man was I shocked and disappointed!!!!  First, there was quite massive overloading on MW.  It was so bad that the SSB detection basically wouldn't work.... the 10 kHz splits were pretty well smeared together and I don't know what else was going on...  The radio was not at all happy connected to the giant 70' x 100' Super Loop.  I had hoped to at least hear 774 and 1566 with the G6, since both were in the middle between 10 kHz stations and each was running S-8 or so when I tried.... there was nary a trace, even though there did seem to be a slight "gap" between each pair of 10 kHz. stations. All that I can figure is the massive amounts of RF coming in from the big loop was simply desensitizing the radio.  In any case, attaching a major outside antenna to the G6 for MW should only be attempted in the far Out Back, like Grayland, where there are no nearby stations.  I'm not at all sure how it would behave there, even.  I should add the front end was overwhelmed and there were ghostly and not so ghostly MW signals at least as high as 10 MHz on shortwave.Its really clear why the designers restricted the MW band to the small ferrite bar and not an outside antenna.

I suspect that the SW part of the radio would work OK on an outside antenna, without the ferrite bar loop that I added.... which is feeding massive MW signals to the front end.  I'll try that after I take the added MW loop out of the antenna circuit.

My biggest disappointment was the SSB capabilities of the radio.  I suppose that it is true that the G6 circuit will demodulate signals transmitted in SSB, though I did not look around on the ham bands for a SSB signal to try it out and I'm not sure.  It is true that you can zero-beat an MW AM signal using the slow tuning and true that you will understand the audio.  HOWEVER, I'll bet my entire pension that you are still listening to both side bands.... it ain't SINGLE SIDE BAND at all! Those of you old enough to remember DXing before SSB will no doubt recall listening to an AM signal with the BFO on. If you tuned to the center of an AM signal and then zero-beat (centered) the BFO over it, you could tune up and down the band hearing a descending whistle until you hit the center of a signal, and then the whistle would go right back up as you tuned past. Well, imagine that BFO fixed on the center of the AM frequency and unable to be tuned independently from the main tuning of the radio..... What do you have, then???   You have a frequency or carrier marker, but you are not able to select one side band or the other to listen to, to dodge adjacent channel slop, or dodge IBOC or whatever.  So the usefulness of the mislabeled G6 "SSB" is quite limited for an international MW DXer and non-existent for those who DX on domestic frequencies.

There are other limitations to the "SSB" detection system offered on the G6.  The "SSB" detection is clearly intended to be used with the slow tuning rate, which actually feels like slow analog tuning. It takes almost four full rotations of the knob to go one kHz. That's fine for clarifying a signal and none too slow, at that.  However, its useless for slow band scanning in "SSB" to detect international carriers.  You can use "SSB" in the fast tuning mode (a 1 kHz tuning step, when in "SSB.") That capability, if everything else worked as an international MWaver would wish, would be marginally useful.  The optimum tuning step would be 0.1 kHz, but the full kHz would be somewhat useful. Of course, the design of those other things actually work against its use as an international DX machine.

The "SSB" capability has one further nasty habit: When in Fast tuning mode (what you would use for Int. MW) the BFO seems offset about 300 Hertz to produce a garbled growl. I think that is so that you will know that you are in "SSB." You can then switch to Slow tuning and clarify..... HOWEVER, when you switch back to Fast tuning, it jumps back to the 300 Hertz growl!!!  It does that every time.  Unless my unit is defective, it is simply another example of the engineers dumbing down a circuit for the "convenience" of unsophisticated users. Grrrrr!

CONCLUSION
Since I've verbally stood on this radio and jumped up and down, I need to remind myself that these sets WERE NOT DESIGNED FOR DXing!!!  We are absolutely misusing these receivers from the designers' point of view. As Colin implied in his dxer.ca review, the G6 could be a really good set for the suburban or, especially rural person (too sensitive for many urban uses) who wished to program listen on shortwave or, even MW. Its a nice little radio with a superb strength meter and LCD for its size and pretty reasonable audio quality. That is exactly what the Eton/Grundig designers were challenged to provide, I would guess.

For the Domestic MW DXer, the plusses are 1 kHz resolution and the sensitivity (outside urban areas) and the minuses are a useless SSB capability (for DXing) and fairly wide selectivity. For the International MW DXer, the G6 is one of John Madden's four-drumstick TURKEYS. It is one of life's little ironies that the "SSB capability" that disqualifies this radio as an official Ultralight radio is so useless for DXing MW.    

There went $100 right down the drain!

John B.
Orcas Island, WA, USA
Rcvrs: WiNRADiO 313e, Eton e1, Ultralights
Antennas: Two 70' x 100' Conti Super Loops, West and Northwest

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