Kenwood YK-88C

Name: Kenwood YK-88C
Brand: Kenwood

A 500 Hz crystal filter in a metal can. It's the little plug-in that turned a general-coverage HF rig into a serious CW machine.

Overview

The Kenwood YK-88C is not a radio. It's a crystal filter - a CW-only accessory, part number L71-0211-05, built in Japan and sold as an option for a long list of Kenwood HF transceivers and receivers. A used TS-440S sometimes sells for more than an identical-looking one down the page, and the answer is often sitting inside the IF strip: this filter, or its absence.

Start with the passband. Kenwood rated the YK-88C at 500 Hz at the -6 dB points, with a center frequency of 8,830.7 kHz, the standard Kenwood IF. That's the value in the surviving documentation, and it's the one to trust. The "8.83 MHz" figure on some marketplace listings is the same number rounded off, not a different filter. For CW, 500 Hz is the sweet spot. It's narrow enough to carve a single signal out of a crowded 40-meter evening, and wide enough that the note doesn't ring like a bell and the tuning doesn't become a knife-edge exercise. The -60 dB bandwidth is quoted at 1.5 kHz, which tells you how steeply the skirts fall: signals a kilohertz and a half away are already buried more than 80 dB down.

Physically, it's a small plug-in module. Some listings call it a "solder type" filter, so read the listing carefully if you're buying one to install. It's designed specifically for the Kenwood radio series, and the compatibility list is long: the R-5000 receiver, the TS-120S and TS-120V, the TS-130S/SE/V, the TS-180S and TS-180V, the TS-430S, the TS-440S, the TS-530S and TS-530SP, the TS-660 and TS-670, and the TS-830S. Marketplace sellers routinely narrow it to "fits the TS-440, TS-430 and others," and one listing describes a unit pulled "from [a] 830s." If you own a Kenwood HF rig from that era, there's a decent chance this filter drops in.

Key Features

500 Hz Passband at -6 dB

At 500 Hz wide, this is a genuine CW filter, not a compromise SSB/CW unit. It's the middle child of Kenwood's CW filter family. It's narrower than the SSB-oriented options, and distinct from the YK-88CN that shows up in the same manuals. For most operators, 500 Hz is the practical choice: enough selectivity to separate close-spaced signals, without the tuning precision that a 270 Hz filter demands on a drifting band.

8,830.7 kHz Center Frequency

The YK-88C sits at Kenwood's standard 8.83 MHz IF. That shared center frequency is what makes it a drop-in for so many radios, since the module slots into the same socket across the range. Listings that quote "8.83 MHz" and listings that quote "8,830.7 kHz" are describing the identical part.

Steep Skirts — 1.5 kHz at -60 dB

The shape of the response matters as much as the width. The YK-88C's -60 dB bandwidth is specified at 1.5 kHz, and the guaranteed attenuation is quoted at more than 80 dB. In practice that means a strong signal 1.5 kHz up the band is knocked down far enough to stop punching through. That's the kind of figure that separates a real crystal filter from a ceramic approximation.

Plug-In, Solder-Type Module

Installation varies by host radio and by the specific filter variant. Some listings describe the YK-88C as a "plug in filter," others as "solder type." Buyers should confirm which they're getting and which their radio expects before buying. This is the single most common source of confusion around the part. The module is designed specifically for the Kenwood series, so it's not a universal fit across brands.

Broad Kenwood Compatibility

The documented applicable-radios list runs from the R-5000 receiver through the TS-120, TS-130, TS-180, TS-430S, TS-440S, TS-530, TS-660/670, and TS-830S families. Sellers commonly cite the TS-440S, TS-430S, TS-830S, TS-530S, and TS-130S. The source material also carries an "and possibly other radios" caveat, so the list is long but not claimed to be exhaustive.

Historical Context

Kenwood built the YK-88C in Japan as an optional accessory for its HF transceiver and receiver line. The surviving documentation doesn't record production years. The RigPix entry carries placeholder dates, and the only firm date anywhere is a single "1986" label on a service-manual listing, which isn't confirmed as a production year. So the manufacturing window isn't documented, even though the radios it fits span a well-known stretch of Kenwood's HF output.

The record does show a parts ecosystem. The same manuals that cover the YK-88C also list the YK-88S, YK-88SN, YK-88CN, and YK-88S/SN as separate filters with their own part numbers (L71-0208-05, L71-0220-05F, and others). Those are distinct models and shouldn't be confused with the YK-88C. The YK-88C's own part number is L71-0211-05.

Collectibility & Value

There's no reliable price data for the YK-88C. The filter turns up on eBay, Marktplaats, shopozz.ru, and nerfd.net, but the captured research contains no actual price amounts. There's only a note that one Canadian listing's "price includes shipping within Canada," with the figure itself missing. Anyone trying to value one is working from live listings, not a documented market.

Condition descriptions are all over the map, which is typical for a small accessory that spends decades inside a radio. One seller offered a "500hz solder type CW filter in Excellent shape." A Dutch listing described a "goed werkend" (good working) example. A shopozz.ru listing advertised a YK-88C-1 as "NOS" (new old stock) in "very nice shape." At the other end, one owner listed a unit that came "included with a recent radio purchase but not required," with the note that "the filter has not been tested." Because the YK-88C is a passive crystal module, an untested unit is a genuine gamble, and there's no documented repair or parts-availability path if it's dead.

The relationship between the YK-88C and the YK-88C-1 is not documented anywhere in the available sources. They may be revisions of the same filter, but nothing in the record confirms it, and no source states the difference.