Tag ft-891

FT-891 with SDR panadapter on the 2nd IF

By in Radio accessories Tag , ,

Our buffer interface named IFace can be used to add an SDR panadapter to the Yaesu FT-891 transceiver on the second IF at 450 kHz: this can be useful when using SDR receivers with limited maximum operating frequency.

The steps are very simple; simply look at the circuit diagram for information on where to tap the IF signals. This radio uses multiple mixers; we’re interested in the second one in the reception chain. The following image shows the radio’s block diagram.
For the FT-891, the frequency of the second IF is shown at the top right in the following image.

This radio, in fact, uses different mixers. In particular, we will have to use the first of the RX chain. The following images show the block diagram of the radio. For the FT-891 the first IF is shown in the small table in the following image.

The following images show the exact points in the circuit diagram where to take the IF signal.

We now proceed to identify the exact points on the printed circuit board where to take the IF signal to be sent to the IFace. The following images show the sampling point for the IF signal and for the power supply for the buffer interface.

In order to purchase an IFace use the button below.

ATTENTION: Though installing the IFace is not difficult, you do this at your own risk. TSP S.r.l. is not responsible for any damage, unwanted side-effects or whatever.

For more information, do not hesitate to write to us using the form below.
Have fun!

Name

FT-891 SDR: IU7RAM testimonial

By in RF Tag , ,

Below are the notes relating to the installation of the IFace interface inside the Yaesu FT-891 by IU7RAM Piero. In general, this work is done to be able to extract an IF signal from the radio reception chain so that it can be used to make an SDR panadapter and add an external SDR receiver. The application scheme is shown in the following image.

The signal to be sent to the external SDR receiver is taken immediately after the first receiving mixer and the frequency to which it will be tuned will be 69.450 MHz.

The RF signal at the mixer output is taken at the point shown in the following image.

The task of the IFace buffer card is to provide the power needed to correctly drive the external SDR receiver circuits: in practice, an impedance adaptation occurs between the mixer circuitry and that of the receiver. In general, the intensities of the signals of interest are small fractions of mW. During transmission, however, the powers are in the order of tens of W or even more, and this can be a problem for the external receiver, especially if it is working in isofrequency with the radio. Therefore, it is generally good to use the PTT signal to disable the buffer, a unique feature of the IFace, but this is not the case as the reception and transmission signals have different paths.

The following image shows where to take the IF signal.

Below are some pictures of the installation done by IU7RAM.

The following three images are from a first quick test during which it was verified that both the radio and the interface were working correctly.

As for the IF signal, it is worth noting that the use of a coaxial cable to connect the IFace input to the mixer output is not recommended. Its use involves the addition of a parasitic capacitance in parallel to the circuits downstream of the mixer with consequent degradation of the signal. Instead, it is good practice to use a small conductor, possibly very short, to reduce the aforementioned parasitic capacitance to a minimum.

This image shows how to connect the IF signal to the IFace. A thin conductor (0.14 mm) coated in green plastic material is used. As already highlighted (repetita iuvant), it is not recommended to use a coaxial cable because it introduces a non-negligible capacity in parallel to the components of the mixer circuit and would modify its performance. The coaxial cable can instead be safely used as an output from the IFace.

A small hole was drilled in the back of the radio to attach the SMA-f connector.
Once the work is completed, the result is shown in this short video.

https://youtube.com/shorts/zCcF1BtFEOA?feature=share

Thank you very much IU7RAM Piero!

To purchase an IFace you can use the following buttons.

ATTENTION: Although the installation of IFace 2 is not difficult, it is done at your own risk. TSP S.r.l. is not responsible for any damage, unwanted side effects, or anything else.

FT-891 with SDR panadapter

By in Radio accessories Tag , ,

Our buffer interface named IFace can be used to add an SDR panadapter to the Yaesu FT-891.

The operations to be performed are very simple, it is sufficient to obtain from its wiring diagram the information on the points where to take the IF signals.

This radio, in fact, uses different mixers. In particular, we will have to use the first of the RX chain. The following images show the block diagram of the radio. For the FT-891 the first IF is shown in the small table in the following image.

We now proceed to identify the exact points on the printed circuit board where to take the IF signal to be sent to the IFace. The following images show the sampling point for the IF signal and for the power supply for the buffer interface.

In order to purchase an IFace use the button below.

ATTENTION: Though installing the IFace is not difficult, you do this at your own risk. TSP S.r.l. is not responsible for any damage, unwanted side-effects or whatever.

For more information, do not hesitate to write to us using the form below.
Have fun!

Name

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