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Wildchild
Intermediate Member
Username: Wildchild
Post Number: 137
Registered: 9-2003
| | Posted on Tuesday, January 25, 2011 - 9:59 pm: | 
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I know there is a receive diode mod for the receive end of a galaxy 949 959 and so on im wondering if there is a mod for the galaxy DX77HML receive and if there is what type of diodes would I have to buy and where is the locations for the change |
Wildchild
Intermediate Member
Username: Wildchild
Post Number: 141
Registered: 9-2003
| | Posted on Thursday, January 27, 2011 - 6:06 pm: |
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Still looking for info on the schottky diode receive mod if this helps the radio has the 360014 pc board |
Big_m
Intermediate Member
Username: Big_m
Post Number: 115
Registered: 9-2007
| | Posted on Friday, January 28, 2011 - 8:40 pm: |
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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.
Today I will be using a 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 half’s, 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 (TR’s) 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 (D’s) 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; it’s 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 it’s 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 |
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 154
Registered: 10-2002
| | Posted on Friday, January 28, 2011 - 10:31 pm: |
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Big m , Do you have any info on th dx series radio's from Rci? SMT is no problem. Just slow. |
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