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Realistic HTX-100 all band mod did not work, help?

A

Adamf

Active Member
Jan 20, 2016
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Hi all, I picked up an HTX-100 that was stock, I carefully did the all band mod and I am pretty handy. I cut the trace properly ( and did not cut anything else) and then soldered the 10K resistor to the appropriate pin with 5VDC. After all this I find it still only covers 28-30mhz, can not get below. Again, I checked the trace cut and where there was continuity before between pics 28/29 on the IC going to the surface mount resistor there is no more continuity which shows the trace was cut. The 10K resistor was properly soldered to the correct pin from pins 28/29 on the IC. Radio still works perfectly but won't go below 28mhz. Any help out there good people? Thanks, Adam
 
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just a thought,, are using a freq counter to check,,,, because if i remember right the mod changes the band but the face readout still stays in 10 meter range,,, and why change this,, because all you have then is usb and cw on 11 meters,,,,
 
Hi, when the mod is done the frequency reads out from 26 to 30mhz. Anyway, hoping someone can help. Thanks, Adam
 
Hi, I will post the information which can be seen by Googling but I am hoping someone is familiar with this situation. Thanks, Adam:

Remove bottom and top covers.

Remove the PLL board and tray that is held in by 2 screws on each side of the radio.

After you remove the board you will see a 4 sided surface mount chip IC 1208 that has 64 pins.

Look to the right of the chip and locate the 4th and 5th pins from the top right of the chip, pins 28 and 29.

Notice they are soldered together and run to a trace to a surface mount resistor.

Carefully cut the trace next to the 2 pins. Now locate 2 rows of pins to the top of the chip.

The bottom row last pin on the right has 5 volts DC on it.

Solder a 10K resistor to that pin and to the pins 28 and 29.

Now reassemble the radio and your done.

The radio will now tune 26 MHZ thru 30 MHZ.

radioshackhtx100freqmod.jpg
 
Below copied and pasted from rogerbird's site. Note the highlighted portion below.

http://rogerbird1.20megsfree.com/htxconv.htm


HTX100 FREQUENCY CONVERSION

Remove bottom and top covers.
Remove the PLL board and tray that is held in by 2 screws on each side of the radio.
After you remove the board you will see a 4 sided surface mount chip UC-1208 that has 64 pins.
Look to the right of the chip and locate the 4th and 5th pins from the top right of the chip(pins 28 and 29).
Notice they are soldered together and run to a trace to a surface mount resistor.
Carefully cut the trace next to the 2 pins.
In some cases, you may have to unsolder the pins from the pad, because there is a trace that connects to the pad
that goes under the IC. (So just cutting the outside trace will not be enough, the pins will still be connected to ground)

NOTE: BE CAREFUL, THE PINS ON THE MICRO ARE BRITTLE AND MAY SNAP IF BENT TOO MUCH.

(I suggest unsoldering the pins, and carefully lifting the pins and sliding a mica insulator under the pins, then soldering the
pins to the resistor added in the next step).

Now locate 2 rows of pins to the top of the chip.
The bottom row last pin on the right has 5 volts DC on it.
Solder a 10K resistor to that pin and to the pins 28 and 29.
Now reassemble the radio and your done.
The radio will now tune 26 MHZ thru 30 MHZ.


73
David
 
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Hey David, thank you Very much, I had read that somewhere but did not take notice, your article is better and makes sense so will try that later or tomorrow. Good job and thanks for caring! Adam
 

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