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WR954Offline
Post subject: Galaxy DX 2517Schotky diode mod and more  PostPosted: Jan 29, 2011 - 03:23 AM
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Joined: Jul 28, 2008
Posts: 663
Location: Grass Valley, California
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Ok all, I had the pleasure to work on Ron's (9wire) radio. He had a serious audio garble issue on both TX and RX. Got into it and first thing I noticed was the mod listed by Ray (tsgr) about the power supply mod, so I did that mod, alas, issue was still there. So, I started on a total alignment on the radio and could not get the TX carrier oscillator section to align at all, Hmm, bad crystal. Ordered one from Galaxy and got it installed and hey, now we are getting somewhere. Next I did the Schotky diode mod, D1, D2, D30, D31 and one transistor. Pretty impressive for the change on AM RX, reduced the white noise and brought the RX up some but I was not impressed with it on SSB. I fiddled some more with the alignment on the RX chain and was able to reduce the white noise while maintaining the level of RX. Ok, lastly, I noticed that a strong SSB signal was swamping the AGC circuit causing a roughness in the audio. So, I found that there is a mod for that and removed D42 and installed a 100K ohm variable so I could set the AGC to a better speed. Lastly, while working on the radio, I had one of the bulbs for the meters blow, noticed that they were not original bulbs and it was no biggie, I had plenty of spare ones so I installed two new bulbs and put them back into there original socket. Finished walking through the rest of the radio and all else seems to be good. Put it on the air and fine tuned both LSB and USB, coarse clarifier at 12 o'clock and the fine at almost 1 o'clock you can switch between the two modes and not have to touch the clarifier. Had a nice QSO with WR494 Paul, he was on his base on his new Kenwood TS480SAT and I used that to fine tune it all. Paul is about 60 miles from me by road (about 40 or 45 as the crow flies) and got great reports, then talked to WR577/NB577 up north of me, WR149 Rich, WR625, 5330, and many more. All within 100 miles or less. So end result is
The Shotky mod in my opinion is great for those that are AMer's, so-so for SSB, the AGC mod helped the timing of the AGC circuit but is very sensitive to adjustment, Power supply mod stabled the flickering lights. Otherwise, the radio is remaining stock.

That is my quick review.
 
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milkmanOffline
Post subject: RE: Galaxy DX 2517Schotky diode mod and more  PostPosted: Jan 29, 2011 - 04:14 AM
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Joined: Sep 08, 2007
Posts: 533
Location: Eastern, US
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Here's more.
How to perform the 2sc2999 and Schottky diode swap for increased receive gain and less noise.


As many of you know there are a few ways to boost the incoming signal, generally this is done with a pre-amp style device; the drawback to a preamp is that it also boosts all other noises as well. It works the same as turning up the volume on your radio, as you can tell it does not help much if at all. What can you do to help? Well by swapping a few parts for upgraded parts you can make your radio more sensitive by boosting the incoming signal and helping to make the radio quieter on receive. The best part is that sense we will be working with the first IF stage of the radio all the garbage that would normally be boosted with a pre-amp will be filtered out so only the other radios carrier will be boosted. We will also help out the noise blanker section of the radio for quieter operation. This will not change the signal you receive on your meter but it will make a 3 s-unit signal as loud as a 4.5 s-unit signal. It also does not make your radio more prone to being overdriven up close. The swap is relatively quick, taking anywhere between 10 minutes for the experienced to 40 minutes to the first timer.

Uniden Grant XL but the same applies to the Grant LT, Cobra 148 GTL, Uniden Washington, Cobra 2000 GTL, General Sherman, Texas Ranger 296, and countless other clones.

Tools needed
soldering iron
solder sucker, or c0pper braid
pen
silver solder
small side cutters
right angle pic (makes removing small parts easier)
#2 phillips screw driver

Parts needed - less than $15
1- 2sc2999 High Gain, Low Noise Transistor ( or nte107**)
4- 1N6263 Schottky Barrier Diodes (or nte583, ecg583, sk9975)
1- Transistor removed from the TR-14 position


You can begin by removing both the top and bottom case halfís, There is a total of 12 screws that need to be removed (4 per side, 1 on top and bottom, and 2 in the rear). I find the speaker easier to unsolder rather than clip the nylon zip ties and unplug from the main board. If you chose to unsolder the wires at the speaker remember that the White wire is the Positive (+) lead.

Take a look at the component side of the radio and find the positions outlined below. They are TR-14*, TR-19*, D1, D2, D21, And D22. These areas are where we will be working. Also take note of the orientation of the transistors (TRís) and note that the flat side faces the rear of the radio, It is important that the new parts be installed the same way, The same holds true for the Diodes (Dís) as the stripe must be facing the correct side on the new diodes.



I like to start with the transistor at position TR-14, this is the Am Detector. You need to unsolder this from the backside of the board; itís easy to find its location on the rear by holding the radio up to a bright light and using a pen to mark one of the legs. Make sure itís a pen and not a pencil. Once you have the Transistor lose, you can place it aside as you will be using it again in a second. Place the new 2sc2999 transistor in the TR-14 position with the flat side facing the rear of the radio. Flip the radio over and solder each leg. Heat the joint for 2-3 seconds before applying solder. A good joint is shiny joint not dull and grey. If it is you need to heat the joint longer.



Move over to the Transistor at TR-19 and remove it. Take the Transistor you removed from the TR-14 position and solder it in place, Again the flat side will face the rear of the radio. This is the ssb detector.

You can now replace the diodes at D1, D2, D21, and D22 with the new 1N6263 diodes. These are low noise diodes that help quiet the natural hiss of the radio. The bands on the D1 and D21 diodes will face towards the mic connector, the bands on the D2 and D22 diodes will face away from the mic connector.





you may want to have the recieve section of your radio aligned, i have found that most radios will not need one if the radio has been aligned before.

*early model radios will be marked with a Q instead of a TR, they are the same component.

**the nte107 can be either hit or miss, when nte bins there parts they have a few transistors that cross over to the nte107 part (including the stock piece) so there is a very good chance you will not be receiving an upgraded part. The 2sc2999 however is an upgraded part and you should find one before using the nte107 if possible.

TR-17, D1, D2, D23, D24

Galaxy DX 33, 44, 55, 66, 73, 77, 88, 99, 11b, Pluto, Super Galaxy, Galaxy II, Saturn, SSB, Melaka, RCI2980, Eagle 2000, Connex 3300 (all), Superstar 3600, 3900 (all), Osaka 3900, General Lee, Voyager VR9000, Alan 87, Nortstar Galaxy clones and other radios that use the EPT-3600 series Main Board.

TR-18 (Q), D1, D2, D34, D35

RCI-2950 & 2970 (non dx) Mirage 2950, Sommerkamp 2000, Galaxy Saturn Turbo, Galaxy DX 22B, Galaxy DX 2527, RCI-2990, Eagle 5000, And other radios that use the EPT-2950 series Main Board.




TR-17 (Q), D1, D2, D30, D31

Galaxy DX 919, 929, 949, 959, 979, DX 2517, DX 2547, DX 45MP, DX 48T, DX 93T, DX 95T, Ranger RG66, RG99, Texas Ranger TR696, TR6300, TR6900 (all), General Grant, Cobra 148f gtl dx+, Connex 4400, 4800, and radios that use the EPT-0929, EPT-0696, and EPT-6900 Main Board

_________________
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CEF 502
DX #502
 
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WR954Offline
Post subject: RE: Galaxy DX 2517Schotky diode mod and more  PostPosted: Jan 29, 2011 - 04:45 AM
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Joined: Jul 28, 2008
Posts: 663
Location: Grass Valley, California
Status: Offline
Yep, there are several radios that this may be done on, I think I will try a few more but if I do not see much for SSB, then it is not of much interest to most of the ones I know. They, like me, rarely talk AM anymore. But, I have not given up yet, I will try it on a few more and see what the results are.
 
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