DG7YBN / FT-102 / Relay Replacement
  Last Update Apr. 25th 2016


Overview on relays to replace
Before Starting

Board by Board

Main Chassis Relays on Socket
Relay Unit (PB-2354) inside the PA Cage: RL01
RF Unit (PB-2342)
IF Unit (PB-2343)
Local Unit (PB-2345)
Final Board (PB-2355)

Relays en Detail & Other

Relay Data
Meter Lamps Replacement
Things I would do next time at it

Yaesu FT-102 Relay Replacement


About three years ago I bought myself a relatively cheap FT-102. The front plate looked like it had been involved in a traffic exident but the price was alright. Collectors of this Yaesu benchmark: do not blame me for the front plate mod and scratches - I bought it like this, honestly. And with a bit fiddly tuning it did in excess of 160 W out from 160 m on. At that time the RX seemed alright. Though an occasional extra click on the Mic PTT had to encourage the RX to come up bright. The other sign of worn relays which is mentioned unisono: is a deaf RX when switching off the RX amplifier. With the RX only coming back to life after another push on the PTT.
This seems to be the dawn of when the relay issues are becoming serious I think. And when I put my FT-102 back as part of the station after 2 years of non use ... well that was it. RX deaf, hollow space like sound and no signals on no band ...

Actually I had much respect opening the case of the FT-102 at all. But as I knew that with time the relay issue would but grow and finally it had to be done ... . Follow me on my journey through the FT-102s relays. Read all the mentioned other FT-102 relay replacement websites, I might have missed some things, and it is good to have a second view on complexe topics and then take to the task or find someone who does it for you.

This FT-102's serial no. is: 2 H 010887

First no. = year of production, that should then be 1982 here? A very early model so.

Other websites about the FT-102

• NC4L's Yaesu FT-102 Resources
• EB5AGV's Yaesu FT-102 page
• PDF: FT-102 Survival Guide - Fox Tango International

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Transceiver of Champions?

... nowadays maybe 'Transceiver of Champions in handling the small soldering iron'
at least until the relay replacement rally is done. Which is why I liked to add this tutorial.

So why have an FT-102 then?

QST's Product Review, Yaesu Eletronics Corp. FT-102 HF Transceiver, Oct. 1983

  'One might be baffled by the excellent receiver dynamic range ...'

• Noise Floor (MDS): -127 dBm (with CW filter)
• IP3: +18 dB (80 m), +19.5 dB (20 m)
• Receiver Dynamic Range: 95 ... 102 dB
• No synthesiser or PLL noise, because there is none
• Capable bandpass filters, same technology as in the FT-1000MP Mark V field
• Lowest transmitter distortion ever measured by QST: -40 dB (14 MHz) at nominal input power

Read in full at NC4L

Top view on the opened FT-102

View this photo enlarged

On the right, below the PA cage, with all the tuning axis rods running above it, we find the RF Unit board which
has the majority of tricky to replace small relays embedded. See all the filter coils?

Bottom view on the opened FT-102

View this photo enlarged


Before lifting any of the covers disconnect the FT-102 from mains and WAIT a couple of minutes to allow the PA power supplies HV capacitors to discharge. Do not fool around with High Voltage. This PA runs 900 V DC. Which is lethal. Be warned now!

Overview an relays to replace on what unit

   Relays listed per unit

Before Starting

   Do you know whats ahead? Are you prepaired? Read this first please

Main Chassis Relays RL 1 & RL 2

This is the easy bit. Really easy going, you not even need to come close to a soldering iron for changing this pair.
The RL 1 and RL 2 are straight standard socket type industrial relays around EUR 6.50

   Read a step-by-step description how to replace the Main Chassis relays

Relay Unit (PB-2354) inside the PA Cage: RL01

This is your warm up coarse to get into gear for overhauling the RF Unit

   Read a step-by-step description how how to replace the Relay Unit relay RL01

RF Unit (PB-2342)

Completed except for the odd RL02

   Read a step-by-step description how to replace the RF Units relays

IF Unit (PB-2343)

Did not do this one yet

   Read about the RL01 on the IF Unit, what it does and why I have not replaced this one

Local Unit (PB-2345)

Did not do this one yet

   Read about the RL01 on the Local Unit

Final Board (PB-2355)

Did not do this one yet

   Read about the RL01 on the Final Unit

All Data on the Relays

   Read about the replacement relays en detail

Meter Lamps

   Read about FT.102 Meter Lamp Replacement

Things I would like to have done if I only had known before...

• Replace the SO266 PL bushing by a PTFE insulated one, or better a quality N-bushing

• Think of a way to install a BNC bushing for a separate RX antenna

• ... and for separate RX - TX outs for transverter operations

• Find and replace the 'inside PA cage Relay Units RL01 with some more solid, larger contacts relay, 16 A instead of 10 A

• Use brighter LEDs for the Meter Lamps, and do both sides in one go, and same LEDs for same brightness both meters

Finally ...

Though I did not go all the way replacing the relays I am hoping to provide some useful information
how to refurbish the great FT-102. Complex challenges are managed best when viewing the problem from
many aspects or sides. So go thru the other sources linked to on top of the page carefully.

73, Hartmut, DG7YBN

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