Yaesu FT-980 tips, tricks and mods

This particular transceiver is one of my (if not THE) all-time favorite among HF rigs. It's not as sophisticated as, say, a K3S or IC-7800 but the front panel gives you everything you need to operate the radio.

Its innards - particularly, the IF strip - bear more than a passing resemblance to the FT-901/902 series of just a few years prior. Think of a '980 as a fully synthesized FT-902 with an extra (455KHz) IF stage. The CPU has memories - 12 channels in all - and a number of accessories could be connected to the rear panel ACC connector. Among those in my inventory are an FL-7000 HF amplifier, an FC-757AT automatic antenna tuner and a factory-modified FTV-901R transverter. The '980 has the ability to directly display the transverter frequency on the 6, 2 and 432-435MHz bands. Slick. The PA section uses transistors rated at twice the nominal 100w advertised output; these are run at 24V to ensure good linearity and minimal IMD.

All this isn't without warts. The major Achilles Heel with the rigs (as with the Kenwood 930/940) is a potentially overheating then malfunctioning power supply which will destroy things in the PA compartment. There's a slick fix from Compudigital for the Kenwoods; I've written up the '930 mod on the site. Space is the final frontier for the '980 - the same Quint switching power supply as spec'd as a replacement for the 930/940 simply won't fit the Yaesu. I'm investigating options for this situation and will post them as the thread evolves.

A wideband IF output for use with a band scope is missing. And the rig won't transceive on 60M though it does cover all the post-WARC '79 allocations. A couple of fixes for that are in the works.

Tip #1 - If your tuning becomes erratic

I currently own four FT-980s. One has every option including all the accessory filters, the iambic keyer module and an RF board that's been modified with Yaesu's "Gen TX" kit. The others are slightly less accessorized, right on down to #4 which is bare-bones and will ultimately become my bench mule for modification development and testing. Needless to say, the first rig is permanently in the lineup and is my go-to 40/75M position.

Recently, its tuning became erratic. I've run the radio in memory mode for a couple of years so it hasn't been dialed around the bands very much during that time. The VFO acted normally when tuned up the band but down resulted in no change save a KHz or so at one specific point of the encoder revolution. Almost sounds like a dirty chopper wheel, right? After removing the rig from the lineup I set it aside for a couple days (after replacing it with one of the others) and today I opened everything up to have a look. Encoder area looked clean but I blew it out with compressed air regardless.

Onto the test bench. Upon power-up everything was fine. What was changed or missing?

The memory batteries. :doh:

There is a dual AA-cell holder that's accessible under the bottom cover via a small door. I'd read elsewhere around the 'Net about weak batteries causing CPU flakiness, so here's another account of such. All of my '980s that are in service use rechargeables for their memory backups so if yours develops any frequency-control faults, there's the place to look first. An a simple fix to boot.

Tip #2 - Cool the power supply

The most common malfunction with one of these transceivers (also with the TS-930/940) is the failure of the 24 (or in the case of the Kenwoods, 28) volt section of the power supply, this due to the cooling fan becoming sluggish or inoperable - leading to a rise in pass-transistor temperature and eventual breakdown, which puts full supply voltage on the PA devices. Things tend to go bad at this point. From a number of years of run-time with the FT-980, I can attest to the fact that their onboard supplies run at an elevated temperature. The PA cooling fan (which also cools the PSU) will occasionally turn on even if the rig is just receiving.

There are several fixes for this, ranging from the quick-cheap-dirty to the complex and elegant. Time, money and space dictate the way to go here.

Simplest approach: An external muffin fan

I have a number of Drake FA-7 fans floating around the parts stash at any given time. These are a low-volume 110VAC Papst unit, originally designed to cool the TR-7, PS-7 and TR-5 equipment. Behind each of my FT-980s in the lineup there's an FA-7 sitting on a computer mouse pad (to deaden noise) and this is set to blow towards the power-supply area of the radio.

Intermediate approach: Rework the PSU cooling arrangement

A one-piece metal cover extends across both PA and PSU heatsinks. this can be cut in half, the PA side replaced and a frame which will hold two 70mm, 24VDC computer fans attached in its place. Mine will consist of sections of 1/2" aluminum angle, joined with low-temp aluminum brazing rod then painted or powdercoated after all mounting holes are located and drilled. A center plate is also required to cover a gap between the fans and this can be fabricated from aluminum. Power is taken from inside the radio through a jack installed in a mounting plate; the plate uses an existing (blank) hole in the rear panel that was covered with tape during factory assembly. This plate will also be used to mount an RCA jack for a panadapter output - more on that (plus pictures) to follow.

Most complex approach - Remote the power supply

Two operating voltages are sourced by the OEM PSU: 24V@15A max, and 12V@5A max. The entire PSU assembly can be removed from the radio, installed in an SP-980 speaker enclosure and cabled to the transceiver. Bulkhead-style Anderson Powerpoles would be ideal for either end of the circuit. Similarly, a pair of Quint switching power supplies (24V@20A and 12V@5 or 10A) are small enough to fit in an SP-980. Use the same bulkhead-connector approach to couple the units together.

It's too bad that Compudigital doesn't offer a drop-in switching-supply solution for the FT-980 as they do for the TS-9x0 series. I converted my '930 a couple of years ago and never looked back.