A panorama adapter for the IC-7300? What’s the point, you might ask, the IC-7300 has such a nice spectrum and waterfall display? Right, but unfortunately the IC-7300 has no output for an external display. The PTRX-7300 provides something even better: an IF output to which you can connect any SDR receiver. So the remote control of the IC-7300 gets a completely new dimension.
The PTRX-7300 extends each IC-7300 by an IF output. This output allows you to connect a second receiver (SDR) parallel to the IC-7300 and display its spectrum on a large PC screen. The advantage: The Icom’s preamplifier and prefilter are used twice, and the transceiver automatically switches between transmit and receive. The RX of the 7300 is not affected because the adaptor uses precise impedance matching of the receive signal. And the best thing is: This pan adapter is very easy to install and, if necessary, just as easy to remove. Nothing is permanently modified on the transceiver, soldering is not necessary. All cables needed for the installation are included, the installation is described in detail and with pictures.
Other solutions to add an RX output to a transceiver simply pick up the signal without worrying about impedance adjustments. Usually a simple power splitter is used. This attenuates the level of the received signal by up to 3 dB. Not so with the PTRX-7300! Due to the careful design of the circuit, the tap of the IF signal is high-impedance and therefore does not load the receiver of the IC-7300 at all, the receive level remains the same. And in the case of transmission, the attenuation is high, typically better than 60 dB. This ensures that the connected SDR receiver cannot receive any transmit RF.
The PTRX-7300 board is professionally manufactured and equipped with high-quality components. A milled aluminium angle is used instead of the tuner socket of the IC-7300, which is routed to the outside with the supplied cables. The additional IF output is mechanically very stable and inconspicuously fixed without having to make any permanent changes to the Icom transceiver. The RF signal is picked up and looped through via an existing plug connector on the circuit board; here, too, nothing has to be soldered. The power supply of the buffer amplifier of the PTRX-7300 is provided by the Tuner connector, which is also looped through. The current consumption is only 30 mA, leaving enough power for the external tuner. The installation only takes a few minutes, and a dismantling without residues is possible at any time without problems.
With the built-in PTRX-7300 pan adapter, any SDR receiver can now be connected to the new IF output, for example the DXpatrol or a Colibri SDR or others. The control software of the SDR is used on a computer, for example HDSDR, SDR-Radio, SDR# or SDR-Uno. Another program – OmniRig – links the SDR software to the CAT control of the IC-7300. This makes it possible for the transceiver to be controlled by the waterfall of the SDR program and always display the correct frequency. All this while the Icom transceiver with all its functions remains the same as before. So you have the best of both worlds – the traditional control via the VFO button on the radio as well as the comfortable operation via the computer.
Icom 7300 Panadapter
Software Defined Radio (SDR) technology has started to revolutionize the way we use radio. With low cost SDR hardware and its open source software support , we can set up a high performance radio station at home even using a personal computer.
When we consider SDR as a digitizer hardware which consists of mostly digital circuits, we may have performance issues due to weak analog front-end. On the other hand, conventional radio rigs have strong channelizing input filters, including low noise amplifier, antenna protection and other signal conditioning circuits.
Although we have these features in conventional radios, we do not have any software flexibility as in SDR systems. Proper combination of conventional radio front-end along with low cost SDR hardware enables us to create higher performance radio with software flexibility. This addresses us to point proper “RF tapping” panadapter with the rigs already in use.
As radio amateurs, we are using one of the world most popular radio rigs ICOM IC-7300 in our station. This rig is very satisfiying direct sampling radio in terms of price/performance ratio. On the other hand, it has no RF output capability which is a major drawback for its uses. As you can see from online amateur radio resources, having an RF output with ICOM IC-7300 is highly demanded. Amateurs would like to use this rig with low cost popular SDRs like RTL-SDR, AirSpy, SDRplay, HackRF and softwares like HDSDR, SDRSharp, GNU Radio as well.
To meet this demand several attempts have been made by other radio amateurs and companies until now, but non of these solutions were a true panadapter and satisfying either. These were nothing but a method which only splits/switches antenna signal into two paths by sampling one path with SDR, or rerouting antenna signal path into the SDR directly. In other words, these approaches were actually antenna signal tapping rather than internal RF signal tapping.
These methods have a lot of drawbacks such as not utilising any of front-end filter, LNA, antenna protection and other signal conditioning features of the rig. We should not classify these solutions as panadapters because these are just antenna signal routing methods without utilizing front-end of the rig.
As we are radio amateurs/engineers who uses ICOM IC-7300 actively, we have worked on ICOM IC-7300 internal schematics, layout and mechanical drawings in order to figure out a true panadapter solution. After heavy brainstorming, we come up with a smart, innovative and seamless way to sample RF signal of ICOM IC-7300. We believe this is the key solution for the radio amateurs who would like to use their ICOM IC-7300 with SDR.
A true panadapter should be able to get integrated into the rig easily, so that anyone can do it by their own without requiring any special skills, such as soldering, cabling, assembling, etc. We have taken following requirements as major guidelines for our design process;
1. RF tapping point should have a connector to avoid any soldering in order to prevent the rig from any damage.
2. There should be an opening on the equipment chassis to take panadapter cable out, extra drilling on the equipment is not allowed.
3. Installing the panadapter should not result any compromise in terms of functionality. For instance if you use tuner connector hole as panadapter access, you are not able to use external tuner simultaneously.
4. Panadapter should be used with SDR simultaneously, both should be able to tune same or different frequency.
5. Equipment should work properly after panadapter is plugged. No performance degradation such as signal loss or additional noise is allowed.
6. All process should be reversible, so that user can revert the rig back to the original configuration.
All of the outlined requirements above have been met with our innovative approach. We designed, tested and verified first PTRX-7300 products, now we are proud to announce.
Utilizing active high impedance probing technique to sample bidirectional TX/RX signal line. Because circuit is just sniffing (not loading RF signal line), thanks to its high input impedance amplifier, it can not be sensed by the rig and has no adverse effect on normal operation.
There is no 3 dB loss as in the case of power splitting approach to sample the signal. Amplifier is designed with state of art components for ultra low distortion and low noise. Active and passive components are from well-known vendors, such as Analog Devices, Texas Instruments, AVX, TE Connectivity, etc.
Beside designing high performance amplifer, there is also need for proper connectorized access to RF signal line. Fortunately, IC-7300 has a connector on its PCB designated as J1431 where you can sample TX/RX signals. Antenna RX signal reaches this point after passing through input filters and low noise amplifiers. There is also low power TX signal going to Power Amplifier. TX signal level is low enough (<500 mVpeak) to monitor with same SDR hardware.
PTRX-7300’s schematics, PCB and mechanical model has been specifically designed for IC-7300. Tuner connector opening of the rig on back panel is used as panadapter mounting hole. Bigger size tuner connector has been replaced with a smaller rectangular one, the MCX RF connector which is carrying RF signal also placed beside it.
An aluminium fixture is designed and CNC machined to place panadapter to the tuner opening on the back panel of the rig. Figure 2 is showing mounting scheme. Figure 3 is showing back panel RF and Tuner connections of panadapter. Figure 5 is showing previously mentioned tapping point on schematics, layout and wiring diagram of IC-7300 service manual.
Amplifier circuit of panadapter also needs a DC power supply to operate. Best way to meet supply requirement is to find a connector carrying DC voltage inside the rig rather than using bulky external power supply. For this purpose we discovered that tuner connector designated as J331 is a good candidate on PA UNIT PCB.
This connector is originally passed to back panel of the rig for external tuner connection via a cable assembly. We replaced this cable with a new one and passed tuner connector to the output panel again over panadapter PCB. DC power rails available on tuner connector are used as power supply of the amplifier.
Amplifier only draws 30 mA current so doesn’t hurt tuner power rails which is capable of supplying more than one ampere current. Figure 4 is showing block and wiring diagram of panadapter.
The table below is showing comparison between PTRX-7300 and typical antenna signal switching/splitting/routing approaches
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