AMATEUR RADIO FOR THE GREAT OUTDOORS
Antennas including linked dipoles, telescopic poles also ham radio kits - everything you need.
If you are thinking of leaving your ham shack with your radio, take a look. We can help.
Our new LASERBEAM-VARI digital variable audio filter module is the perfect addition to your project or even to your existing radio. Unlike analogue filters, digital filters provide near-perfect characteristics. Because of the way that they are implemented, they are better than analogue filters in almost every way!
W2AEW reviews the LASERBEAM-VARI
LASERBEAM-VARI Modules been designed for ease of use. One simple control allows you to continuously vary the bandwidth or the centre frequency of the filter. All settings produce the same great filters with flat passbands and steep skirts. Whether you need passband tuning, filters for digital modes and APRS, low pass filters or CW filters, the LASERBEAM-VARI does it all in one compact module. Dial up EXACTLY the filter you need.
Great for all modes: SSB-CW-Digi-AM-NBFM.
A single clickable rotary encoder provides the main functionality. Click to switch between variable bandwidth or centre frequency. Store your favourite setting as a power-up default. Simple but very effective. The filters are continuously variable and always have near perfect characteristics unattainable with conventional analogue techniques.
Simple to use: the instructions are downloadable here.
These plots have been made by testing a LASERBEAM-VARI using a professional audio spectrum analyser (QuantAsylum QA400). Remember that the LASERBEAM-VARI can synthesise any bandpass filter that you want (200-3500Hz). Click on the links below to see the filters.
The most common question I get is "can I fit your filters inside xxx type of radio?". The answer is generally yes.
LASERBEAM-VARI modules are ready-built and easy-to-use. Make a few connections and you will soon be good to go.
In most radios they can be fitted before the volume control. You may need to adjust levels. The only control you need to bring to the front panel is the rotary encoder although the mode LEDs are very useful. In essence, some ingenuity is needed to retro-fit VARI-BEAM filters. The effort is worth it though, as it really can make old receivers sound quite spectacular.
Our optional Filter Integration Kit provides you with the main additional hardware that you might need to get up-and-running for making an external filter unit. This is perhaps the most flexible option as you can easily use your LASERBEAM-VARI filter on different radios.
IMPORTANT NOTE: The LASERBEAM-VARI module is not suitable for use with our BOXA-DUAL filter enclosure kit
LASERBEAM-VARI modules have been designed to be easy to use. Connections are kept to the minimum:
An LED on the module lights if the input level is too high making it easy to set up your filter. The audio input is protected on the PCB so you can't easily damage it!
The filter module will drive high-sensitivity (e.g. > 110 dB SPL/mW) earbuds directly. For higher outputs a simple audio amplifier such as an LM380N could be added. LASERBEAM-VARI modules are Altoids-friendly!
The modules are perfect for use in existing radios or an an outboard filter. We used one with a Rockmite and the difference was simply amazing! These filters are also great with the popular PIXIE transceiver.
Supply voltage: 5 - 15 Volts (reverse polarity protected)
Typical supply current: 50 mA @ 12 Volts
Filter type: multi-tap FIR (KBD Window)
Phase response: linear
Module size: 36 x 36 mm (approx 1.4 x 1.4 inches)
Weight: 5.5 grams
Voltage gain: 1 or 4 (selectable)
Ultimate rejection: better than 60 dB
Passband ripple: <0.15 dB
Input impedance: 8000 Ohms
Output impedance: 750 Ohms
Output type: differential (can be used single-ended)
Maximum AF input Voltage: 2.4 V pk-pk (input protected)
Minimum AF input Voltage: 300 mV pk-pk (recommended)
Maximum AF output Voltage: 2.4 V pk-pk
Processing delay: 22 mS
|Characteristic||VARI-BEAM FILTER||IF Crystal/mechanical filter|
|Bandwidth options||Fully variable||1 per filter|
|Within AGC loop?||No||Yes|
|Ultimate rejection||>60dB||> 50dB (but usually well away from filter bandwidth)|
|Filter gain||Yes - if required||Typically 6dB loss|
|Residual noise||Yes - low level||No|
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Posted by Michael Iafrate on 29th Apr 2017
I remember making my first audio filter years ago using an RC network and some op amps. It worked OK but nothing like this. It is amazing how selective this filter can be. The instructions are clear and simple. It took a few minutes of experimentation to get how the two variables interact. This is a great addition to a receiver that needs a little more selectivity.
Posted by Ulli DC8SE on 21st Jan 2017
Its the first time that I test a filter that calculate the BW and the center frequency.
The filter is superb!!!!
But the tuning of BW and center is not easy! !
From my opinion I missing two LED lines
one line for the BW and one line for the centerfrequency.
summary: I recommand this Filter!
Posted by Peter, ZL1SX on 27th Aug 2016
After watching the review by W2AEW I was tempted.
It arrived within a few days, and that's to New Zealand. After a bit of thinking, I mounted all of the external passive components on a matrix style PCB, used a couple female header plugs in case problems came up, which they didn't, to the main board and fired it up.
Let me say it lives up to the promise.
I did add a little push button in parallel with the function switch on the encoder to enhance the experience. Used a nice little aluminium case with a 9v battery and the push button on top. Wish I could post a picture here.
What is not emphasized is that you just connect the headphones output of the transceiver, my FT 817, and then connect the headphones to this unit. Simple as.
Posted by Rick JI1HSV on 9th Aug 2016
I originally purchased the CW filter with the intent of comparing it to my variable SCAF filter but before I could build the unit SOTABEAMS released their VARI filter so I got one and started building a dual channel DSP filter with audio amps. (Sent the CW filter for re-progamming, different review)
I was certainly not disappointed, this filter REALLY works. It is a bit subtle though, there is none of the ringing or super peaking you would find in other types of audio filters, adjacent signals just disappear!
Initial setup of the VARI filter can be a bit confusing as both center frequency and band width are variable. I used a IPad app called 'SignalScope' where I can see a FFT of the audio. I first set the center frequency to the side tone of transceiver, switch to bandwidth mode and push the 'default'. I then set the
bandwidth and pushed the switch again.
You have to be creative in mounting the filter as there are no holes on the board and smd parts are mounted very close to the edge. I inverted the 10 pin header pins and then these plug into a perf board that has 10 pin female headers. This
allows mounting the LED and encoder resistors under the DSP filter on the perf board.
I use two of the VARI filters followed by 2 watt audio amps and some mini relays for bypassing everything for AM SWL operation.
I would definitely recommend using a DC source of no more than 9VDC. There is no reason to unduly stress the little 3.3VDC SMD regulator on the DSP board.
Cost/Performance is excellent. Service from SOTABEAMS is excellent.
If anyone has any questions my call is on QRZ.com
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