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| Reviews Summary for Vectronics VEC-820 CW Filter Kit |
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Reviews: 4
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Average rating: 4.3/5
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MSRP: $35
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Description: The VEC-820K Electronic Kit gives an incredibly narrow 80 Hz bandwidth and extremely steep skirts with no ringing for razor sharp selectivity. It will pull CW signals out of interference in any ham radio band. You simply plug the kit into your radio phone jack to drive phones or between audio stages for full speaker operation. You can select three bandwidths: 80, 110, 180 Hz. Noise is down at least 60 dB one octave from center frequency for 80 Hz bandwidth. Center frequency is 750 Hz. The kit's 8 poles active IC filtering uses low Q cascaded stages. Stops ringing. No impedance matching needed. No insertion loss. The kit uses a 9 volt battery (not included). The kit measures 1¾ x 3½ x 3½ inches.
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Product is in production.
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More info: http://www.vectronics.com
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write your own review of the Vectronics VEC-820 CW Filter Kit.
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M0RNA
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Rating: 4/5
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Dec 31, 2008 09:40
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Works well
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Time owned: 0 to 3 months
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I purchased the kit and the separate case for use with an FT817. I am not a regular constructor of kits, but found the instructions to be clear and helpful. I built the kit, and housed it in the case in a few hours, and was pleased when it worked first time.
Tuning around the bands, I was pleased at the way that the desired signal was boosted when tuned in properly to ~750Hz using the VFO or RIT. Adjacent signals were still audible to some extent, but greatly attenuated. This filter definitely seems to boost weak signals to quite a comfortable level, and the 3 filter widths are all usable and pleasant to listen through. NB: It is of central importance to select a CW side tone note of 750Hz.
I would give this kit a 5/5 except for the fact that there was no knob included with the kit for the filter selection switch and I am not certain if this was deliberate or an oversight.
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N6MUK
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Rating: 4/5
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Jan 7, 2008 10:25
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Its a really good, solid CW filter
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Time owned: more than 12 months
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It's about as good as an old school audio cw band pass filter can get!
1) The widest (180 Hz) setting is perfect for cleaning up a wide open pass band for scanning/ signal searching. If you have a rig that lacks audio selectivity, this is necessary.
2) The medium (110 Hz) setting is only occasionally useful to me because my rigs have inboard filtering that I prefer when the band is not too crowded.
3) The narrowest (80 Hz) setting is impressive and useful. Once I got used to it, really can't live without it. It will ring a bit. Sometimes the cw note, if weak and noisy, will set off a bit of a howl. Its actually pretty tame and not very troublesome. Sometimes, a weak cw signal that is barely hearable, will pop out of the noise when perfectly centered through this 80 Hz filter and become easy copy. You must tune carefully and your receiver's RIT is useful for this.
This filter really shines when used in combination with a rig's existing IF filtering. It is important to check the center frequency of your rigs filters to make sure they are 750 Hz or close to that. You can’t adjust the center of the Vectronix pass band; its fixed at 750 Hz.
Overall a great and cost effective addition to the shack!
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KC9CS
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Rating: 5/5
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Jan 28, 2007 15:52
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Works well, fun kit!
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Time owned: 0 to 3 months
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I build a lot of QRP equipment from kits. This kit only took a couple of hours to build, and that included some modifications and getting it into a cabinet. The kit I built was the upgrade from the VEC-820 listed above..mine was the VEC-821 called the Super CW Filter Kit. I think it's essentially the same as the 820 but includes a 1 watt audio amplifier for driving a speaker. I modified the kit with a switch to be able to switch between headphones or an internal speaker in the cabinet. All the listed parts were in the kit (although the kit took nearly 2 months on backorder--ordered it the last week of November, it arrived in late January) and I sorted them and checked the inventory list. I typically save egg cartons for my small parts when I build, the egg sections can be written on with pen or marker for the parts identity and this makes the build go quicker. 43 individual electronic parts make up the kit, then you have the IC sockets (3) a rotary switch and some other hardware. Following the manual you should be able to put this together without a problem IF you identify the parts correctly and place them correctly. Some of the resistors are very tiny and I needed magnifiers to see the color bands well enough. As each part is placed, check it off in the manual as in the old Heathkit manuals. One thing the manual wasn't very clear on is the connections to the speaker, and the input from your radio. In fact, a speaker isn't included, nor are any input jacks, probably because each persons needs will be different. In my case, I made a fast dash to the nearby Radio Shack store for 1/8" chassis mount stereo phono jacks for the input. The kit comes with a 9 volt battery clip but the kit will run on anything from 9-18 volts. I'd suggest a miniature female plug and the mating male plug to get power from a 12v battery source since I run all my QRP rigs from a single 12v 750mA/hour battery.
The kit does contain some polystyrene capacitors and newcomers should be careful with not applying too much heat in soldering these in...they're fragile.
Okay...so how does it work? Great! There's a bypass position on the switch and switching the filter into the audio circuit one can hear a distinct difference both in audio bandwidth and noise. The kit has a noise reduction circuit and it drops noise 15 db. When switching to the first position the bandwidth is 180hz, second position is 100 hz and the last 80 hz. I sensed only a wee little bit of ringing in the 80hz position and it was not offensive. In fact, sometimes switching through the various positions would reveal a station 'hiding' under the QRM/QRN of a nearby signal. Pretty nifty, especially for low tech QRP rigs. The CW tone is pleasant, and centered about 750hz. Switching from the bypass position to the filtered position also activates the 1 watt audio amplifier and the audio boost is noticeable. This bit of audio boost is essential to some QRP rigs which typically use only headphones and are somewhat finicky about the audio impedance they see. This kit solves that problem, although you can't expect it to drive a very large speaker with any results.
Bottom line: the kit does what it says it will do, and it does it very well. It separates interfering signals and can make the difference in hearing or not hearing a station. And it is inexpensive. It's not a full featured DSP, but it will benefit the QRP operator in pulling those signals out. All in all a fun kit that works!
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K2JN
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Rating: 4/5
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Apr 13, 2004 18:54
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Inexpensive CW audio filter
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Time owned: 0 to 3 months
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The Vectronics VEC-820 is an inexpensive audio filter that utilizes an eight-pole active filter design. The project can be purchased as a simple board kit for about $20. An additional $15 gets you a nice cabinet with extra connectors to complete the project. Components provided in the kit are fairly decent quality and the printed circuit board is medium grade in quality. At a careful pace, the kit can be completed in one evening by the average kit builder. There are only 27 components, including two LM747 op-amp chips. I chose to take my time and complete the kit in several evenings making sure to double check some of the hard wiring to connectors and switches. In addition, novice kit builders should take extra care so as not to apply too much heat when soldering the eight polystyrene capacitors.
Instructions are fairly easy to follow and both the board kit and the case kit come with separate manuals. The case uses a self-stick aluminum-look labels to add that commercial feel. I wasn’t too fond of the labels since they are easy to scratch or can come loose if applied incorrectly.
When complete, the kit provides a 2-position screw terminal for input and a ¼” monaural jack for output. I hooked up my filter to my Lowe HF-150 using a pair of Kenwood HS-6 head phones. Filtering response was fairly decent on all settings and optimized for 750-800 Hz tone. Ringing was not noticeable on 180 Hz, and minimal on 110 Hz and 80 Hz bandwidth settings. Running some tests on the 40-meter band, I found the 180 and 110 Hz settings most suitable to my ears.
Overall, I’d give this kit a 2-thumbs-up. It’s inexpensive, easy to build and will suite most needs for CW operators who need extra selectivity without paying a fortune.
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