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Reviews For: Elecraft CP1 Directional Coupler

Category: Tools & Test Equipment for the amateur radio work bench

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Review Summary For : Elecraft CP1 Directional Coupler
Reviews: 5MSRP: 39
The CP1 is an ideal companion to Elecraft's 2T-Gen two-tone test generator.
It is a dual directional coupler that provides high directivity, can be internally
or externally terminated, and can be constructed with a coupling loss of
either 20 or 30 dB. It can be used to sample a transmitter's forward power
and reflected power output. For two-tone measurements, the forward power
port can be connected to an oscilloscope or station monitor for display of the
transmit envelope.

The unit is quite versatile; for example, it can be used with a diode detector
to create a 25-W or 250-W SWR bridge. For more advanced applications, the
CP1 can be used with a spectrum analyzer and tracking generator to sweep
the return loss (SWR) of an antenna or other device in real time.

The unit operates over a 1 MHz to 30 MHz frequency range. When built as a
30-dB coupler, it can handle up to 250 watts. When built for 20 dB coupling,
maximum power is 25 watts. In either case, coupling loss is accurate to +/-
0.25 dB, and directivity is approximately 30 dB.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
WA6NUT Rating: 2022-09-10
Useful for PureSignal Sampling Time Owned: more than 12 months.
I've found the CP1 to be useful for sampling the output of an HF transceiver or linear amplifier when operating with adaptive predistortion (PureSignal). My CP1 is configured for 30 dB coupling, along with a variable RF attenuator (Texscan RA-54) for feedback from my AL-811 amplifier output to my Apache Labs ANAN-10E transceiver (or an Elecraft AT1 0-41 dB attenuator could be used to adjust the feedback level). Be careful not to exceed the power rating of the CP1 (250W when configured for 30 dB coupling).
AE5X Rating: 2022-09-09
An oldie but a goodie Time Owned: 0 to 3 months.
I finished building this kit earlier today, then hooked it up to my VNA. It's a keeper:

With the recent proliferation of nanoVNA's, reduced prices of oscopes and spec-ans, this kit has more usefulness, for a larger number of hams, than it did when first introduced years ago.
K7NG Rating: 2014-01-16
Couldn't find any better one Time Owned: more than 12 months.
A decent directional coupler is a very useful accessory item for any ham station. Once a ham learns what a coupler does, and what its' limitations are, there are so many things that can be done with one it would be hard to list them all.

You could go out and pay a LOT more money for commercially-manufactured dual directional couplers and not get any better performance than either version of the CP1 provides. Just a decent amount of care and effort to build this kit and you have something you might find indespensible in a hurry.

I am fortunate to have access to calibrated, high performance test equipment, and I tested my CP1 (30 dB HF) coupler after I built it, and found that the coupling was accurate to within +/- 0.4 dB from 1.7 to 30 MHz, and the mainline VSWR was better than advertised. With a small amount of fudging (moving windings around just a little) I got it to show me coupling within +/- 0.3 dB, and directivity better than spec. across that same range. Good job, Elecraft!
AC0LP Rating: 2010-12-19
Make your oscilloscope into a Ham Radio Monitor Scope Time Owned: more than 12 months.
I use this device instead of a dedicated limited function Ham Radio monitor scope. I monitor my transceiver when running digital modes with the coupled signal passed to my Tektronics TDS2012 scope. This way, I am certain that my signal is not over driven and remains clean. It takes just a few minutes to assemble and hook up - a truly worthwhile accessory for the shack.
WA3TTS Rating: 2007-01-26
Good Deal Time Owned: more than 12 months.
I built the -30 dbm version after determining I was not going to find an affordable HF directional coupler on e-bay (NARDA, etc.) Quick and easy build. They claim the unit is only good to 30MHz but I found its response acceptable at 144 MHz. Buy two, build both versions!!