#95 - Yaesu 857D Radio Modification - Step-by-Step Guide
I recently started hearing people talk about doing single-sideband or SSB mode on 2-meter radios. Unfortunatley searching for a 2-meter radio that also does SSB is a little difficult.
I realized a couple weeks ago that my Yaesu FT-857-D all-band, all-mode radio does allow SSB on 2-meters.
Although I am able to do SSB on 2-meter, the stock Yaesu 857-D is not the best radio for this because the original frequency oscillator that comes installed in the radio from the factory would allow the frequency to drift a bit while transmitting depending on the temperature of the radio, which is very noticable when using SSB mode.
As you are transmitting, the radio heats up a bit and while you are receiving it cools back down. This would allow the frequency to swing just a tad both to the left and to the right of your chosen frequency causing distortion in the audio. The more the temperature fluctuates, the more the frequency waivers, and the more distortion.
Another local ham (KW4TO) suggested that I replace the stock frequency oscillator in the 857-D for an upgraded one made by Yaesu that is temperature compensating. Taking his advice I ordered the replacement TCXO-9 High Stability Crystal Oscillator from DX Engineering which finally came with FedEx a few days ago.
Supposedly this is a simple, quick and easy upgrade modification to the radio. Simply open the top of the radio, locate the stock frequency oscillator, pop it out, pop the replacement in where the original was, and close the radio back up. We shall see . . .
One of the beauties of being a licensed amateur radio operator that makes ham radio so different from any other radio service is that amateur radio operators are our own radio repair technicians. With our license, we are not required to take our radios to a licensed repair technician for repairs, modifications, or upgrades, that ability is already included in our license from the FCC. With every other radio service, you must take the radio to a licensed repair technician for any work on the radio, including programming the radio. We are legally allowed to program, service, upgrade, maintain, and even build our own radios from scratch.
Today I decided to put that ability to use by replacing the factory oscillator with the TCXO-9 myself to see how easy it actually is. As a relatively new ham who has never attempted to modify or build anything myself I was very intimidated at the thought of tackeling this project, but I can tell you that unhooking the radio from my installation at my hamshack was the hardest part of the whole project.
I will walk you through the whole process, step-bystep so you can see how easy the entire process is. Believe me, if I can do this, ANYONE can do this.
First off, if your radio is installed you need to unhook the power, antennas, external speakers, and anything else connected to the radio so that you can work on the radio without anything getting in your way.
While it is not absolutely necessary, having a good quality extendable magnifying work light comes in really handy for any small electronics job like this.
Sit the radio down on a sturdy workspace with plenty of good lighting so that you can see what you are doing easily.
On the top of the radio we are going to remove the two small phillips screws that are closest to the front of the radio and the one closest to the back of the radio. The remaining two screws will remain since they only hold the internal speaker in place in the radio.
Now you want to remove the two small phillips screws on each side of the radio.
This will allow you to carefully slide the top cover off of the radio to expose the electronics inside. Be careful as the small red and black wires for the internal speaker will still be connected to the circuit board at the back corner of the radio.
Carefully unplug the wires by pulling on the connector on the circuit board and not on the wires themselves.
Once you have unplugged the internal speaker from the circuit board you can lay the top cover of the radio aside so that we can locate the frequency oscillator on the circuit board.
If you turn the radio so that the front of the radio is facing away from you, the frequency oscillator will now be in the lower left hand corner of the circuit board directly in front of the heat-sink fins on the back of the radio.
The frequency oscillator will be flanked on either side by white plastic connectors. One with four holes in it on the left side, and the other with three holes in it on the right. Remember this position when we replace the oscillator with the TXCO-9 so that we install it in the right direction. It will only fit in one way, but if you try to force it in backwards you will damage the pins that the connectors are sitting on.
We want to slowly pull out the old oscillator by pulling upwards on it. I am using a set of plastic non-conductive prybars and curved set of electronics tweezers to do this with only because they were handy. A simple common pair of tweezers will also work for this.
Once you have the oscillator out of the radio you can now see the pins that the oscillator was sitting on top of. Make sure that these pins are straight and did not get bent when you were removing the facotry oscillator.
You will notice that the factory frequency oscillator and the TXCO-9 are similar, yet they are different. The factory oscillatorhas the red square on it with an adjustment screw in the center of it where the replacment one does not.
Notice that both have four connectors on the left side in the white plastic and three on the right. This is the way that you will need to install the new oscillator into your 857D.
Now carefully insert the TXCO-9 into the 857D in the same place that you removed the factory oscillator from, being careful that the pins on the circuit board correctly line up to go into the white plastic connectors using gentle pressure applied evenly on both ends of the TXCO-9 until it is firmly seated on the circuit board.
Once the TXCO-9 has been firmly seated on the circuit board the modification is complete. Carefully reconnect the internal speaker wire connector to the circuit board at the bottom right corner of the radio.
Now you are ready to replace the top cover on the radio and reinstall the seven small phillips screws on the sides and top cover.
Now you just need to reinstall your radio by reconnecting the power cable, antenna coax, external speaker, and any other connectors that you disconnected from it earlier.
That's it, you are now finished and your Yaesu FT-857D radio will now be able to handle SSB sommunications on 2-meter without the frequency drifting on you as the temperatore changes inside the radio. A simple easy modification that anyone can do in less than 5 minutes.
Until Next Time,
Aloha & 73