Radios to avoid

This thread is for making a list of radios to avoid when buying secondhand equipment. The reasons should not only be about whether the radio is any good at RX or TX, they should include factors such as component aging and servicability. I'll start it off with a few horrors that have come to me for repair. There's plenty more where these came from!

Rigs to avoid like the plague:

Yaesu FT-290R - Very awkward construction, PITA to dismantle and service. AVOID for the sake of your sanity.
Icom IC-551D - Very awkward to service and dismantle, components do not age well and irreplaceable microprocessor tends to die. Avoid.
Kenwood TS-930 - This isn't a mistake. Huge PLL problems over time, really awkward to service. PLL board in a stupid place, signal board is massive and a pain to remove for servicing. Power supply design isn't great. Components do not age well. Digital board suffers from lots of problems.

Rigs that are great, but have reliability problems:

Kenwood TS-850S/AT - Leaky caps all over, DDS death, ALC voltage supply problems. Controls wear out with heavy use. I haven't sold mine, but I should!
Kenwood TS-440S - Great rigs, but PLL death is inevitable due to glue. A long and annoying task to pick out all the glue and realign.

And some diamonds to look out for :)

Kenwood TS-520, TS-520S, TS-520SE, TS-820S - Old, but age well, built like tanks, can be ok or difficult to service depending on fault.
Yaesu FT-980 - Excellent rigs, most just need realignment. Can suffer from PSU death which kills PA. Repairable though.

Adding to the thread:

Kenwood R-5000:

Same issue as the '440S, and you get 'keyboard bounce' (common to both radios) in addition. I got both of mine for the proverbial song and repaired the VCOs. They're going like champs. Buy a spare keypad assembly - the underlying unit is common to both '5000 and '440; only the buttons are different and may be interchanged. If yours develops a bounce problem due to humidity and oxidation, it may be repairable by drying the assembly out. As a last resort, disassembly and a shot of contact cleaner on all the switch pads...though this is somewhat of a "last resort" undertaking.

Kenwood TS-940S:

The PA device's +28v supply uses pass transistors which are being run very near their maximum ratings. Should the PSU cooling fan fail, it'll allow the transistors to overheat and fail...then take the PA transistors (usually the drivers) out with them.

Fortunately, fixes exist. Replacing the OEM fan with a computer type, ball-bearing unit goes a long way towards ensuring PSU reliability. Exchanging the pass transistors for a part with a higher Vce rating (80-120v) will also prevent problems.

The PLL board in the '940 is also prone to the same problems as the '440/'5000. I bought one (non-operational) for $250 last February; it wouldn't stay in lock. About 8 hours worth of digging into the synthesizer yielded a working set.

IC-701, 720:

First and second generation synthesized Icom transceivers. Both have relatively noisy synthesizers, and the '720 used a rotary stepper-drive bandswitch mechanism - instead of relays like most later solid-state rigs. Though they rarely fail the mechanism has long since been discontinued by Icom. I was not impressed with the '720A's receiver but were the operator to pair it with an R-70 and IC-7072 transceive adapter, the combination works pretty decently.

Avoid any of the early solid state Icom radios that used brass grommets in place of plated-through holes to connect the two sides of the PCB. They are guaranteed trouble.

Bumping this one out of a long slumber:

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Originally Posted by mw0uzo

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And some diamonds to look out for :)

Kenwood TS-520, TS-520S, TS-520SE, TS-820S - Old, but age well, built like tanks, can be ok or difficult to service depending on fault.

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I second the bolded. At the moment there's a TS-820S/R-820 pair in the main station lineup, with another awaiting minor servicing/realignment. Those rigs have been in operation on and off with me since the mid 80s and just keep working. DeOxIt in the potentiometers, on the switch contacts and main harness SIP connectors (every one of them!) does wonders in keeping one of these in good shape.

Quote:

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Yaesu FT-980 - Excellent rigs, most just need realignment. Can suffer from PSU death which kills PA. Repairable though.

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A mistake was almost made. My two '980s - each of which showed several operational faults - came close to going out the door last year as "parts/not working". Rig #1 wouldn't switch modes or bands correctly. This was caused by a bad IC on the CPU Board; it's one of three socketed chips. Easy fix, one the design was understood. Rig #2 wouldn't tune with the VFO knob until it had thoroughly warmed up, although the "5 KHz Up/Down" buttons would tune it. Another CPU fault, this possibly involving a timing circuit in the area of the CPU Board which controls the tuning functions. I swapped CPUs with a spare to get the rig working but will revisit the faulty CPU (and it's potentially bad tantalum capacitors) at some future date.

Another fault with Rig #2 centered on the VFO Board. There's a single 30MHz crystal oscillator which generates the master reference frequency; derivatives of this are used by the rig at several points. If it isn't stable or on the correct frequency, proper alignment will be difficult - if not impossible. Yaesu published a couple of Bulletins over the years which cited performance improvements to this circuit, but what was wrong with mine was that its crystal had drifted to the point that proper netting was impossible.

Yaesu to the rescue - specifically, Jose in their Parts Department. (If you ever see him at an event, buy him a beer for me on the Island's tab.) He sourced 5 crystals from Japan, and while they were in transit I managed to acquire a surplus VFO Board for the radio. While all this was transpiring I got hold of yet another FT-980 with cosmetic damage and managed to get it working electrically. Finally finished up Rig #2's electrical issues yesterday and with the new VFO Board installed it can be netted to zero-beat WWV at every spot in the HF spectrum.

Where was I...power supply issues? Improper cooling?

Given the successes in bringing these rigs back to life I've decided to keep them around. I'm in process of designing an external fan assembly and power interlock; when done I'll document all needed materials and provide drawings for the various bits of metal needed to attach the fans to the rig. This modification is completely reversible and makes use of existing fastener locations; no cutting, drilling or filing required.

The best procedure is to remove the supplies from the rigs and remote them but given that bench space can be a premium, this is a workable compromise.

There's even a spot on the new connector bulkhead plate to route a wideband IF Out (suitable for use with a panadapter equipped station scope like the YO-901). That's yet another mod to make the radio more usable.