Our take
Sharp's R-308J operation manual says the model code is followed by a color letter and specifically maps K to black. Its R-308J/R-309J specification group lists 1.0 cu. ft., 1,100 W output, 120 V/60 Hz and a 12 5/8-inch turntable. It separately lists 1,580 W/13.5 A input, a protected 15-A-or-more supply and two-inch ventilation clearances. The manual identifies these as Home Use Carousel microwave ovens. It gives everyday Popcorn, Reheat and Cook functions, but a search of the manual finds no sensor-cooking documentation. It also names no exact built-in trim kit. The spec footnote distinguishes R-308JK-F, R-308JW-F and R-308JS-F variants with 1,530 W/13.0 A input; those codes are not silently substituted for R-308JK. Amazon B0002ATFHM failed to load, so the exact-model search is used without a direct-ASIN claim.
The Sharp R-308JK fits buyers looking for a documented black, 1.0-cu.-ft. countertop microwave with a 12 5/8-inch rotating turntable. The operation manual lists 1,100 W output separately from 1,580 W/13.5 A input for the R-308J/R-309J group, and requires a protected 120-V/60-Hz supply rated at least 15 A; check the exact unit label because the manual gives a different input figure for separate -F variants. The cavity measures 14 1/2 × 8 1/8 × 15 1/4 inches, and Sharp specifies two inches of ventilation space at the top, sides and rear. The K finish mapping is explicit, while sensor cooking and a trim-kit route are not documented. Sharp calls the family a Home Use Carousel microwave. Amazon B0002ATFHM failed to load during this check, so use the tagged exact-model search rather than claiming a direct ASIN match..
Do not select this model for an installation that cannot provide at least the protected 120-V/15-A supply and two inches of ventilation clearance around the unit, for a built-in opening that requires a confirmed trim kit, or if sensor cooking is essential. Check the nameplate for the exact input because the manual separately identifies -F variants with a different figure.
Pros & cons
What could work for you, and what to consider before buying.
What works in its favor
- The Sharp manual explicitly maps the R-308J K suffix to black and lists 1.0 cu. ft. with 1,100 W cooking output.
- A 12 5/8-inch turntable and interior/exterior dimensions support a more concrete dish and counter fit check.
- The manual provides two-inch ventilation clearances, a 120-V/60-Hz supply and a 15-A-or-more protected circuit recommendation.
- Popcorn, Reheat and Cook functions are documented for the family.
What to weigh up
- The manual does not document sensor cooking or an exact built-in trim kit.
- The published R-308JK-F/R-308JW-F/R-308JS-F input figure differs from the base R-308J/R-309J group; verify the unit label.
- A two-inch gap at the top, sides and rear may constrain a tight counter location.
- The historical Amazon ASIN did not load, so its exact current listing identity remains unverified.
The key details
| Model covered | R-308JK |
|---|---|
| Capacity | Sharp says R-308J is followed by a color letter: K is black, W white and S silver. The row's R-308JK code therefore denotes the black R-308J model. |
| Microwave output | Sharp lists 1.0 cu. ft., 1,100 W microwave output, 120 V/60 Hz and a 12 5/8-inch turntable for the R-308J/R-309J family specification group. |
| Cooking approach | The same group lists 1,580 W/13.5 A input. A separate footnote assigns 1,530 W/13.0 A input to R-308JK-F, R-308JW-F and R-308JS-F; those -F codes are not merged into this row. |
| Installation options | The manual recommends a protected 120-V/60-Hz supply rated 15 A or more, suggests a separate circuit, and requires two inches at the sides, top and rear for ventilation. |
| Finish and turntable | It calls the family a Home Use Carousel Microwave Oven. The manual does not specify sensor cooking or an exact built-in trim kit. |
Performance figures are manufacturer claims. Source checked October 4, 2026. Regional models and included accessories can differ.
What the features mean for you
K means black in Sharp's model code
The R-308J operation manual says the base model is followed by a color letter and identifies K as black, W as white and S as silver. That directly supports the source row's R-308JK/black pairing. It is not evidence that every Sharp model ending in JK is the same oven: R-308J and R-408J remain different base codes. A service-manual page for R-308JK was checked but timed out; the accessible Sharp operation manual establishes the R-308J base and suffix mapping.
The output and input figures answer different questions
Sharp lists 1,100 W microwave output and separately lists 1,580 W/13.5 A input for its R-308J/R-309J group. The manual recommends a protected 120-V/60-Hz supply rated 15 A or more and suggests a separate circuit. Its footnote calls out a different 1,530-W/13.0-A input for exact codes R-308JK-F, R-308JW-F and R-308JS-F. Since this frozen row names R-308JK without the -F suffix, do not attach the -F input figure to it; compare the actual unit nameplate with the family instructions.
A measured tray diameter narrows dish fit
Sharp's manual gives a 1.0-cu.-ft. cavity with internal dimensions of 14 1/2 × 8 1/8 × 15 1/4 inches and a 12 5/8-inch turntable. A plate or container must clear both the round tray and cavity opening; volume by itself cannot tell whether it will rotate without touching the walls. The exterior measures 20 1/2 × 12 1/4 × 17 3/8 inches. Measure the counter and the dishes that matter instead of assuming a nominal capacity guarantees a fit.
Countertop ventilation needs room
Sharp advises leaving two inches at the sides, top and rear for air circulation and says to plan for counter space on at least one side. That guidance has a real effect on the footprint: the cabinet should not be pressed against upper shelves or adjacent surfaces. The manual does not identify an exact built-in trim kit. Do not treat the K color suffix, a countertop description or a tight cabinet opening as trim-kit approval.
Automatic menus do not prove a cooking sensor
The manual describes Popcorn, Reheat and Cook functions and other shortcuts. A search of the accessible operation manual found no sensor-cooking instructions or sensor chart, so sensor cooking remains unconfirmed. Those named controls may simplify common settings but do not show that the appliance detects humidity or adjusts a cycle from food conditions. If a true sensor feature matters, compare a model whose manual specifically labels Sensor Cook or Sensor Reheat.
Use it as a household model, not a foodservice unit
Sharp calls the family a Home Use Carousel Microwave Oven and says it is not designed for industrial or laboratory use. The manual provides no commercial-duty rating or foodservice-cycle specification. Its 1,100-W output does not establish heavy-duty service. Treat it as a household countertop microwave and choose a manufacturer-classified commercial model for repeated institutional or restaurant use.
What else to compare
If documented sensor functions and stronger output are more important than this model's 12 5/8-inch turntable and 15-A circuit, compare Panasonic NN-SD696S. Panasonic's family manual lists 1,300 W and Sensor Cook/Reheat for that model group, but requires a separate 20-A grounded outlet and does not state nominal capacity. Check exact dimensions and the circuit before comparing the two household models.
Before you buy
What does the K suffix mean?
Sharp says R-308J models use a following letter for color and maps K to black.
What capacity and output does the manual list?
The R-308J/R-309J group is listed at 1.0 cu. ft. and 1,100 W output.
What is the input rating?
The family table lists 1,580 W/13.5 A for R-308J/R-309J. It separately lists 1,530 W/13.0 A for -F codes; check the exact unit nameplate.
How large is the turntable?
Sharp lists a 12 5/8-inch turntable.
Does it have sensor cooking?
The accessible family manual describes Popcorn, Reheat and Cook functions but does not document sensor cooking.
Can it be built in with a trim kit?
The manual gives countertop clearances and does not identify an exact compatible trim kit.
Is it classified for commercial use?
No. Sharp calls it a Home Use Carousel microwave and provides no foodservice-duty classification.
Does ASIN B0002ATFHM match R-308JK?
The Amazon page returned an internal error. Use the tagged exact-model search; this entry does not claim an exact ASIN match.
Where can I check the current price?
Use the Amazon link for current offers. Check the exact model, seller, product condition, delivery, and return terms. This page does not display a live price or confirm stock.
Sources & review basis
We use the following manufacturer documentation for the product features above. Our suitability notes and buying advice are editorial judgments based on those features, not measured performance results.
- Sharp-authored R-308J/R-309J/R-310J operation manual; model letters identify finish ↗ — checked October 4, 2026.
- Sharp-authored R-308J/R-309J/R-310J operation manual: model letter/color mapping, countertop placement, family output/input, capacity, turntable, dimensions and home-use classification ↗ — checked October 4, 2026.
- Sharp R-308JK service-manual record checked for exact model; page fetch timed out, so family operation manual is the accessible source for model and features ↗ — checked October 4, 2026.
- Historical Amazon ASIN checked 2026-10-04; fetch returned an internal error, so no direct ASIN mapping is claimed ↗Paid link · We may earn a commission. — checked October 4, 2026.
The decision
Sharp R-308JK is an in-category black household countertop microwave: Sharp maps K to black and lists 1.0 cu. ft., 1,100 W output and a 12 5/8-inch turntable for its R-308J family. It needs at least two inches of ventilation clearance and a protected 120-V/15-A-or-more supply. Sensor cooking and an exact trim kit are undocumented. Keep the separate -F input ratings distinct and verify the appliance nameplate. Amazon B0002ATFHM could not be checked, so the affiliate route is a tagged exact-model search.
Is it the right fit?
Check the exact model and today’s offers on Amazon.