PTK 7350 MG-D is a 5.7 g digital metal-gear servo with 1.5 kg·cm at 6 V for small EPP and indoor RC aircraft

PTK 7350 MG-D is a very small digital servo designed for lightweight EPP aircraft, indoor aerobatic models and other models where every gram counts.

PTK lists a weight of just 5.7 g, metal aluminum gears, dimensions of 19.6 × 23.7 × 8.4 mm, a speed of 0.08 s/60° at 4.8 V and 0.07 s/60° at 6 V. Torque is approximately 1 kg·cm at 4.8 V and 1.5 kg·cm at 6 V.

Those are interesting specifications for such a small servo.

5.7 g is its main advantage

On an indoor 3D model weighing, for example, 120–200 g, a difference of a few grams can significantly affect:

• wing loading,
• center of gravity,
• inertia,
• aerobatic performance.

A 5.7 g servo is therefore naturally more suitable than a standard 9 g servo.

Metal gears

PTK lists Metal Alu Gears.

Compared with plastic gears, metal gears offer greater mechanical durability in a crash or during more aggressive control.

Potential disadvantages include:

• higher weight,
• greater backlash after prolonged use,
• potentially more noise.

In this case, however, the weight remains very low.

Torque of 1 kg·cm at 4.8 V

At 4.8 V, the manufacturer lists approximately:

• 1 kg·cm,
• 0.08 s/60°.

That is sufficient for the small control surfaces of EPP models.

This is not a servo for:

• a large 1.5 m aerobatic plane,
• a crawler,
• a large boat rudder.

Using it outside the small-aircraft category would mean unnecessarily risking an overload.

At 6 V, it is stronger and faster

At 6 V, the manufacturer lists:

• 1.5 kg·cm,
• 0.07 s/60°.

The difference is noticeable.

However, the servo must be powered within its specified range of 4.8–6.0 V at most.

An HV BEC at 7.4 or 8.4 V is not suitable unless a regulator is used between them.

Digital electronics

A digital servo processes the control signal at a higher internal frequency than a standard analog servo.

The result is typically:

• more precise position holding,
• faster response,
• higher holding torque.

A potential disadvantage is higher power consumption while holding position.

For a small aircraft, however, the precise response is very pleasant.

Dead band: 5 μs

The manufacturer lists a 5 μs dead band.

A smaller dead band means the servo responds even to small changes in the control pulse.

This is useful for precision aerobatics, where the pilot needs small, smooth corrections.

Electrical precision: 2.5 μs

PTK lists electrical precision of approximately 2.5 μs.

This is an internal technical specification from the manufacturer.

In practice, the precision of the resulting control will also depend on:

• mechanical backlash,
• the servo arm,
• the linkage,
• receiver quality,
• control-surface geometry.

200 mm cable

The servo has an approximately 200 mm cable with a JR-style connector.

For a small indoor model, this cable may even be too long.

To minimize weight, some modelers shorten cables, but this requires soldering and correct wiring.

Dimensions: 19.6 × 23.7 × 8.4 mm

The servo is very thin.

Its approximate 8.4 mm thickness helps when mounting it directly in a thin EPP or Depron structure.

When gluing it in place, take care not to get adhesive into the gears or output shaft.

Which BEC should you use?

When using three or four digital servos, size the BEC with some margin.

Even a small servo can draw significantly more current when stalled than during free movement.

The manufacturer does not list the exact stall current on the public product page.

Therefore, it is sensible not to use a BEC with no headroom.

Mechanical geometry matters more than an extreme endpoint

If the servo does not have enough torque, using a longer servo arm is not a good solution on its own.

A longer arm:

• increases deflection,
• but reduces the force available at the control surface.

On a small 3D aircraft, the servo arm and control horn need to be matched correctly.

Main specifications of the PTK 7350 MG-D

Who is this servo suitable for?

It makes the most sense for:

• indoor 3D aircraft,
• EPP aerobatic models,
• small fixed-wing models,
• lightweight experimental mechanisms.

Is the PTK 7350 MG-D worth it?

If low weight and metal gears are priorities, yes.

The manufacturer's specifications are very good for a 5.7 g servo.

The most important thing is not to overestimate its category: 1.5 kg·cm at 6 V is suitable for small models, not as a universal servo for large RC platforms.