Tekbox TBBNC1 BNC Adapter Set
TekBox TBBNC1: seven BNC adaptors in a box: BNC to 4 mm banana (plugs and jacks), BNC to screw terminal block and a 50 ohm feed-through termination.
TBBNC1 — BNC to banana, terminal block and 50 Ω termination, in one set
Seven adaptors that connect a BNC instrument to the rest of the bench: 4 mm banana plugs and jacks, bare wire in a screw terminal block, and a 50 Ω feed-through termination — in a box small enough to live in the drawer under the oscilloscope.
Oscilloscopes, function generators and spectrum analysers speak BNC. Multimeters, power supplies, clip leads and most of what is on a bench speak 4 mm banana, and sensors and loudspeakers speak bare wire. The TBBNC1 covers every combination of BNC male or female on one side and banana plug, banana jack or terminal block on the other, so the connection you need is made with an adaptor instead of a soldering iron.
The seventh piece is the one that matters for accuracy: a 50 Ω feed-through termination, SWR below 1.5 up to 1 GHz, so a 50 Ω generator sees its proper load at a 1 MΩ oscilloscope input.
What is in the box
Seven pieces, from TekBox’s parts list, with the position of each in the photo above.
| Qty | Part | What it connects | In the photo |
|---|---|---|---|
| 1× | BNC male → 2× 4 mm banana plugs | An instrument’s BNC socket to banana jacks: a multimeter input, a power supply, a breadboard binding post. | right column, middle |
| 1× | BNC male → 2× 4 mm banana jacks | A BNC socket to banana-lead test leads: clip leads, a shrouded DMM lead, a bench lead set. | right column, top |
| 1× | BNC female → 2× 4 mm banana plugs | A BNC cable end to banana jacks. | left column, middle |
| 1× | BNC female → 2× 4 mm banana jacks | A BNC cable end to banana-lead test leads. | left column, top |
| 1× | BNC male → screw terminal block | Bare wire into a BNC socket: a sensor, a thermocouple extension, a loudspeaker line. | right column, bottom |
| 1× | BNC female → screw terminal block | Bare wire onto a BNC cable end. | left column, bottom |
| 1× | BNC female / BNC male 50 Ω feed-through termination | Terminates a 50 Ω source at a high-impedance input. SWR < 1.5 at 1 GHz. | centre |
Banana plugs and screw terminals are open connections, not 50 Ω lines, and TekBox gives no frequency rating for the six adaptors that use them. Use them for DC and low-frequency signals — rails, audio, sensors, generator outputs at modest frequencies. The feed-through termination is the RF part: 50 Ω, SWR below 1.5 to 1 GHz.
Four jobs it does on a Siglent bench
Generator into a multimeter
A function generator has BNC outputs; a bench multimeter has banana inputs. The BNC-male to banana-plug adaptor joins the two without a hand-made lead, for an AC level check or a frequency count.
Scope probe where there is no probe point
The terminal-block adaptors take bare wire. Screw a sensor lead, a thermocouple extension or two speaker wires into the block and the signal goes into the oscilloscope on a BNC.
Banana leads into the oscilloscope
Measuring on a power supply or a battery pack with standard 4 mm leads: BNC-female to banana jacks on the end of a BNC cable, or BNC-male to banana jacks straight on the oscilloscope input.
Right amplitude from a 50 Ω source
A generator set to 1 Vpp into 50 Ω shows 2 Vpp on an oscilloscope’s 1 MΩ input. Put the feed-through termination on the input and the oscilloscope sees what the generator was set to.
Specification
| Order code | TBBNC1 (TekBox) |
| Contents | 7 pieces: 4 BNC-to-banana adaptors, 2 BNC-to-terminal-block adaptors, 1 BNC 50 Ω feed-through termination |
| BNC-to-banana | Male and female BNC, each to banana plugs or banana jacks (4 mm) |
| BNC-to-terminal block | Male and female BNC, each to a 2-way screw terminal block |
| Feed-through termination | BNC female to BNC male, 50 Ω · SWR < 1.5 at 1 GHz |
| Packaging | Rigid box, 210 × 130 × 36 mm · 300 g |
| Frequency range of the adaptors | Not specified by TekBox. Banana and terminal-block connections are not 50 Ω lines; treat them as DC and low-frequency connections (see below) |
From the TekBox TBBNC1 manual V1.0 and TekBox’s product page. TekBox publishes no further electrical ratings for the set.
Goes with
The two other TekBox sets we stock, and the cable and lead these adaptors end up on.
Coaxial adaptor set — N, BNC, SMA and TNC adaptors in a case.
Attenuator set — DC to 6 GHz, 2 W, N connectors.
50 Ω coaxial test lead, the cable most of these adaptors go on.
Hirschmann MLN 4 mm lead for the banana side.
Prices ex VAT. All cables and connectors
Questions about the TBBNC1
Are the banana and terminal-block adaptors good for RF?
No, and TekBox does not rate them for it. A banana plug pair or a screw terminal is an open, uncontrolled connection, not a 50 Ω line. They are for DC and low-frequency work — supply rails, audio, sensor signals, function-generator outputs at modest frequencies. The only RF-rated part in the set is the 50 Ω feed-through termination, with an SWR below 1.5 up to 1 GHz.
What is the feed-through termination for?
A 50 Ω signal source expects a 50 Ω load. An oscilloscope’s 1 MΩ input is not one, so a generator set to 1 Vpp shows twice that on screen. The termination sits between the cable and the input and restores the match; it is also the way to terminate a 50 Ω cable at a high-impedance instrument.
Does it fit Siglent instruments?
Yes. Every Siglent oscilloscope, function generator and spectrum analyser input or output on BNC takes these adaptors; the banana ends fit the 4 mm inputs of the SDM multimeters and the outputs of the SPD and SPS power supplies.
Is a cable included?
No. The set contains adaptors and a termination. BNC cables and banana leads are sold separately.
Why does the manual say N connectors?
The parts list in TekBox’s manual reads “N-male to Banana-male” and so on; that is a typo. The product name, TekBox’s own description and the photographs all show BNC, and the set is sold as a BNC accessory set.
What else does TekBox make?
Test accessories and EMC pre-compliance equipment. From the same family we stock the TBCAS1 coaxial adaptor set and the TBAS4 attenuator set, both linked below.
Need a connection this box does not cover?
Tell us the two ends and the highest frequency that matters. We will tell you which adaptor, cable or set bridges them — from this box, the TBCAS1, or a single cable.