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The Yaesu FT-818 – an All band QRP radio

The Yaesu FT-818 QRP All Mode transciever

The Yaesu FT-818 had not even crossed my radar before my interest in microwave. I’d seen it’s predecessor the FT-817 in passing but hadn’t really given it a second though. Looking at all the microwave videos on Youtube, there was one common radio that everyone seemed to use. You guessed it… the Yaesu FT-818. Over breakfast recently with Peter VK3APW, I learned the reason why everyone loves these radios so much, and that is, they don’t spike transverters with RF levels that would otherwise destroy them.

It’s not uncommon for non QRP radios to deliver musch more than a few watts in the first few milli or micro seconds of transmitting. So a great insurance policy to protect your investment in a transverter that may have cost you big $$$ is tou use a QRP rig, like the FT-818 as an IF.

The other great thing about the FT-818 is it can run on batteries, either the rechargeable one supplied, or bought AA bateeries in the battery holder provided. That’s not all though, the more you use this radio, the more you realise how valuable it is in the modern shack.

Why buy this radio?

This radio is a MUST for transverter operation. It doesn’t spike with high level RF that you’ll most likely get from bigger radios (ALC Overshoot). It’s batter operated which is a bonus, but one feature which is really handy for peaking signals for long distance microwave is the ability to generat a beeper with the CW mode!

The beeper is great for firstly finding a weak signal, then it allows for small horizontal and verticle adjustmets to get maximum strength. Probably one of the handiest features for anyone really. Other reasons to buy it is that it’s a tidy, ruggard and well built radio that’s going to handle sand and dust along with knocks and bumps. The only negative is the power lead. Yaesu, what were you thinking! Fortunately there are options.

The Battery

The radio is supplied with a Ni-MH, 9.6 V, 1900 mAh, battery-pack (SBR-32MH), as well as a AA battery holder. You can charge the supplied battery pack while the radio is connected to an external DC supply.

Battery compartment FT-818
Yaesu FT-818
Yaesu FT-818

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Providing up to six watts of power output, the FT-818 is designed for operation on the 160-10 meter HF bands, plus the 6 meter, 2 meter, and 70 cm bands. Whether your preferred operating mode is SSB, CW, AM, FM, Packet, or SSB-based Digital modes like PSK31, the FT-818 is ready to join you on your next hiking, camping, or search-and-rescue adventure!

Features

  • FT-818 Yaesu HF/6m/VHF/UHF 6W Backpack Transceiver
  • TX Frequency 160-10m, 6m, 2m, 70cm
  • RX Frequency 100kHz – 56MHz, 76 – 154MHz, 420 – 470MHz
  • Power output 6W SSB/CW/FM with 13.8V External DC * 2.0W AM carrier * 2.5W SSB/CW/FM with 9.6V 1900mAh or 8xAA batteries (AM 0.7W)
  • Operating Modes USB, LSB, CW, AM, FM, WFM, Digital (AFSK), Packet (1200/9600 FM) * Digital Modes RTTY, PSK31-U, PSK31-L & user defined USB/LSB (SSTV, PACTOR etc)
  • Case Size 135 x 38 x 165mm (WHD)
  • Weight 1.1kg
  • Two colour LCD Multi-function Display (Blue/Amber) * Bargraph Metering of Power Output, ALC, SWR and Modulation * Optional Narrow CW and SSB Filters * AGC Fast-Slow-Auto-Off Selection * RF Gain/Squelch Control * Built-in Noise Blanker
  • Front and Rear Panel Aerial connectors (BNC on front, SO-239 on back)
  • 200 Regular Memories, plus Home Channels and Band Limit (PMS) memories * Alpha-Numeric Labelling of Memory Channels * Automatic Power-Off (APO) and Tx Time-Out-Timer (TOT) * Rear Panel Data, Accessory and Key jacks * CAT System Computer Control Capability (4800/9600/38400bps) and Cloning Capability.

Difference between the FT-817 and the FT-818

  • Increased power output 6W(SSB, CW, FM) 2.0W(AM Carrier)
  • Improved frequency stability ±0.5 ppm : Built-in TCXO-9
  • Larger battery capacity : 9.6V/1,900mAh (SBR-32)

Resources

Unlike some other brands, Yaesu tend to only provide manuals for their radios.

Yaesu FT-818 Operation Manual

Yaesu FT-818 Brochure

Sotabeams FT-818 Powerpole adapter

Setting up the FT-818 for microwave use

Configuring the FT817 / FT818 for transverter operation.

 

A PDF recently found its way accross my desk on how to set up the FT-818 for transverter operation. Credit goees to Lou, VK3ALB for this.

Antenna Scocket Selection

NOTE: Antenna socket selection is band specific; ensure the REAR connector is selected for each band. Look for “R” in display window to confirm selection.

 

Select menu item 07 and rotate VFO to REAR

Output Power

Press the FUNCTION button briefly
Rotate SEL to [PWR, MTRxxx]
‘A’ button sets the RF power and the ‘B’ button set the meter function.

 

• Press A button until you see L with 3 bars (2.5W)
• Press B button to select MTRpwr

SSB Step size

Select menu item 47 and rotate VFO to 2.5 kHz.

SQL/RF-GAIN

Select menu item 45 and rotate VFO to SQUELCH

Rear Yaesu FT-818
The rear of the Yaesu FT-818 with the Sotabeams Powerpole.
Supply Voltage Display

Press the FUNCTION button briefly
Rotate SEL to [CHG, VLT, DSP]
Press the ‘B’ button to display supply voltage

Beeper Operation

Select menu item 17 and rotate VFO to 250ms
Select menu item 21 and rotate VFO to 45-wpm
Select menu item 22 and rotate VFO to 1:4

 

Press the FUNCTION button briefly.
Rotate SEL to [VOX, BK, KYR]
Press the ‘B’ button to enable CW Break-in operation.

 

Insert an open 3.5mm mono plug into the key socket at the back of the radio. Select CW mode and use button ‘C’ to control the keyer.

Simple bias tee modification

Bias Tee Modification

 

If you plan to use the FT 818 as an IF radio for microwave projects as I do, it may pay to perform a simple modification which applies a small amount of DC up the coax for switching sequencers and transverters. I was initially going to use the ACC jack on the rear of the radio, but Peter VK3APW conviced me that it’s one less cable you need to remeber when going portable. It also switches the Minikits sequencer with DC rather than RF.

Warning

Keep in mind that modifying your radio will most likely void any warranty. Also, be carefull with the soldering iron. There are lots of meltable components in the vicinity.

What you'll need

Parts for this modification are minimal. You’ll need:

  • 1 x 10 nano farad ceramic capacitor
  • 1 x 3K9 1/4w resistor
  • small length of hookup wire.

In an original post by Lou VK3ALB,  which is well worth a read, he uses a 4k7 resistor, but after a discussion with Peter VK3APW, who has also done the mod to his radio, he suggested a little less R to help the switching of the SG Lab transverters, so I went with 3k9 which works well. Lou also offers other methods for a bias tee if this mod is not suitable for your requirements.

The Modification

Remove the bottom cover, the one with the battery compartment in it, making note of the different types of screws and where they go. With the rear SO239 antenna jack away from you, you’ll see the place to apply the mod near the realy on the right hand side of the board.

 

Twist then solder one leg of the 3k9 resistor to 10nF cap and one end of the hookup wire. Trim keeping lead lengths as short as possible.

 

Trim and fit the other leg of the resistor to base of the L3081 coil.

 

Solder the other end of the capacitor to the frame of J3003.

 

Finally, solder the other end of the wire to the TX5v point on the PA module.

 

Visually inspect the radio paying special attention to clean soldering.

Outcome

All going according to plan, the bias tee should put about 3.6 volts on both antenna outputs. It’s current limited by the resistor.

 

It’s worth noting that Peter VK3APW suggest the resistor needs to be soldered at the end of L3081 nearest the relay. This proves problematic for soldering. Well it did for me.

FT-818 Simple Bias Tee Modification TX5V connection
FT-818 Bias Tee Modification TX5V connection
Location of the FT-818 Simple Bias Tee Modification RF Connection
FT-818 Simple Bias Tee Modification RF Connection
Board Layout of the FT-818 FT-817 bias tee modification
Board Layout of the FT-818 FT-817 bias tee modification
FT-818 L3801 coil before modification
FT-818 L3801 coil before modification

Click any image for a larger picture.