The best way to describe the DX-SR9’s receiver is very “hot”. There appears to be plenty of sensitivity. There was no problems picking up plenty of signals even with a modest antenna. There is also a 10dB preamplifier that can be activated by pressing the RF key. The RF key also controls a 10dB attenuator and a 20dB attenuator. The default setting for the RF switch is 0dB which turns off both the attenuator and preamp. In use the 0dB setting seemed to the best general setting. Activating the 10dB preamp will increase the signal level, but if you are in a noisy RF area, it will increase the RF noise floor also. If you are in a noisy RF area, the attenuators do a good job of reducing the noise floor with out giving up much in regards to the signal level. Front end filtering seems to be extremely good. The front end rejected strong signals near the center frequency very well. The only exceptions was when the 10dB preamp was in use when two very exceptionally strong signals were very close. Turning off the preamp will fix that. Even in those cases, the interference was minimal. The receiver front end did not experience any overloading with the 20M meter dipole that was used for testing. How ever, your mileage may very depending on the antenna in use.
There is an AGC mode that by default is set to auto. The AGC is automatically set to fast for CW and slow SSB and AM. The AGC can be set to manual through the Function menu so you can set AGC-F or AGC-S to your tastes. You can adjust the AGC on the fly, but the Auto-mode will return the AGC to it’s default settings when the radio is powered off and back on.
The DX-SR9 only has a few additional interference fighting tools available. First of all, there are no Digital Signal Processing modes to be found anywhere. not even a notch filter. However, these can be added when used in SDR mode by the SDR software. The only other noise fighting tools besides the attenuator is the Noise Blanker and IF shift. The Noise Blanker is probably more geared for reducing pulse type noises such from automobile ignition systems. The other feature is the IF shift knob that allows you to separate to very very close signals with a little loss in audio quality. The IF shift on the DX-SR9 was very effective of removing interference from signals a few kilohertz away.
Overall, the DX-SR9 has a very competent and pleasant receiver section. You aren’t giving up too much to more expensive rigs considering that the DX-SR9 is a budget transceiver.
The power output levels can be set by pressing the FUNC and 0 key to three settings, High 100 Watts, Low 10 Watts, and S-Low 1 Watt for the SSB, CW, and FM modes. The AM mode can be set to High 40 Watts, Low 4 Watts, and S-Low 0.4 Watts. So the DX-SR9 can fill in for those who like working QRP, with the bonus of an adjustable internal pot that can be used to adjust the power down to 0.1 Watts. There are other internal pots that allow you to adjust the microphone gain, beep volume, and side tone volume.
Transmit audio using the included microphone is pretty much standard for this level of transceiver, which is pretty decent. However, when used in SDR mode the DX-SR9 can be a audio tweakers dream. When in SDR mode the DX-SR9’s from panel and controls are pretty much disabled. This also includes the front microphone jack. All transmit audio is routed to the rear MOD jack from the PC’s sound card. You can use anything from a good quality USB headphone and microphone set to a professional level audio interface to connect studio mics. You also will be able to adjust audio equalization and compression through the use of 3rd party audio processing software if you wish.
The DX-SR9 also offers VOX and a speech compressor internally, but thats about it.
Other Notable Features
The DX-SR9 has a few other features that are worth mentioning:
Memory and Scanning
The DX-SR9 offers 3 memory banks of 200 channels that can be programmed and recalled. The memory will retain information about the channel such as splits, mode, filter, AGC, NB, Tone, Output power, and Skip. These memories can be labeled with a 6 character alphanumeric label, which is pretty handy. However, at this writing there is no specific software to help program these memory slots for the DX-SR9 from Alinco. So manual entry of these memories and labels could be a time consuming process. The DX-SR9 can perform several scanning functions using these channels or a frequency range such as band, programmed. search, memory, and priority. These scan features are fairly common to most recent HF transceivers.
HF FM Repeater Operation
The DX-SR9 allows you to easily work HF FM repeaters. You can program the repeaters frequency and offset into the DX-SR9 and store the information in a memory slot. The DX-SR9 also supports the use of CTCSS tones if they are being used on the repeater.
Easy Setup for Digital Modes
The DX-SR9 allows you to quickly get operational on the digital modes such as PSK-31 without having to invest in an external interface. You can simply run a 3.5 mm cable between your audio cards line input and the DX-SR9’s front mounted speaker jack. Connect an additional 3.5 mm stereo cable from your soundcard’s line out or speaker out to the rear mounted Mod jack. Setup your PSK-31 software audio settings for audio input and output. Keying is by enabling a feature called DVOX on the DX-SR9 through the Setting Mode Parameters submenu. DVOX is simply a vox circuit tied to the MOD jack. This will place the DX-SR9 into transmit mode whenever audio is heard on the MOD jack. This is about as simple as it gets. The only thing to keep in mind is that you may want to be sure that you turn of all Windows notifications sounds. If not you will probably sharing them with the world.