Manager - NA4M
Manager Notes

Reviews For: Idiom Press/Ham Supply SCAF-1

Category: Filters, Audio: (DSP and others)

eMail Subscription

Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted.
Review Summary For : Idiom Press/Ham Supply SCAF-1
Reviews: 93MSRP: 108.95 kit 148.95 assembled
The new SCAF-1 filter from Ham Supply/Idiom Press makes your radio listener friendly, whether you are an SSB or CW operator. Using a modern but little known technology called SCAF filtering, the SCAF-1 is an active audio low pass filter offering user control of the filter cut-off frequency, yielding a stunning 96dB per octave roll-off of signals above the cut off frequency, and no white noise. It is the perfect partner for your crystal or mechanical filters. And, unlike most audio filters, there is absolutely NO ringing.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
OE5CSP Rating: 2007-08-12
Works very well Time Owned: 6 to 12 months.
My Icom 761 is a fine ssb-rig, but for cw the receiver is a bit too noisy, especially on the low bands.(compared to the K2)
So I was looking for a good cw filter. After reading all the reviews here on eham, I decided to order the kit. Building was not difficult, although the assembly instruction needed a little update.
This filter really helps pulling out signals from somewhere in the noise floor. More than once I wasn´t able to copy anything, but after engaging the Scaf-1 I could read every dit and dah.And besides,the audio coming through the headphones is far more pleasant.
I used the JPS NIR-10 filter and I´m still using the NIR-12(for ssb and am), but for cw I prefer the Scaf-1.
Unfortunatelly the headphone jacket is not on the front side and the sidetone is not bypassed.
WC3O Rating: 2007-05-31
Simple and good Time Owned: 0 to 3 months.
Great filter. Picked it up at Dayton 2007. Very nice PCB. Went together nicely. Worked the first time out. Sounds just like the WAV files on the web site. I have DSP and IF filters on my radio and a QF-1A. The QF takes too long to set it to where you need to be. For CW the SCAF if perfect, flip the switch and turn the knob. Boom! Your done, and it really helps pull the signals out of the mud. I am even thinking about taking and mounting it inside my external speaker if I can figure a way to make it look good. Works well for SSB too. Nice folks to deal with. Buy it, you won’t be sorry.
-Use PowerPoles for power instead of the barrel connector.
-Add some pictures in the manual; even crude drawings would be great. The wording is very good but I’m a picture kinda guy!
-Sell a kit version without the enclosure to be mounted internal to a speaker or radio.
-Add a fuse.
If you like the SCAF, try the Rotor EZ! No CDE rotor is complete without it. Gotta go, DX is calling.
73 WC3O Bob
VE3OU Rating: 2007-05-12
Very worth while addition Time Owned: 0 to 3 months.
Had a chance to buy this unit (new) from another VE3 at a good price, I figured, "whats to lose".
Discovered it performed very well with either of my two rigs, and even with the DSP in my TS-570 it will reduce the qrn present on the signal edge.
On the IC-735 it is a marvel at allowing me to reduce the annoying 800 hz monitor side tone by limiting the higher frequencies.
The little SCAF-1 does perform as advertised!
KA4AIY Rating: 2007-03-16
Works for me and my I-703 Time Owned: 6 to 12 months.
My Icom 703 has a narrow cw filter installed in it but found that the adding a SCAF-1 to the audio provides an distinct advantage in tuning out ringing while shrinking the audio pass. I was skeptical at forst.. you know, one ad after another promising "miracle cures" for QRM and QRN (my biggest intrusion here is localized QRN) and the SCAF-1 is very good at taking it out and then applying the ICOM's narrow CW filter in provides a clear CW signal with greatly reduced ringing and other distortions. My only complaint with SACF-1 is the quality of the switch used... I had to get another one but Idiom, sent one right away. The one I received originally with the kit is a little fragile... it can't take much heat (even with 15 watt iron) when soldering wire to the lugs you can burn the lug out of it's internal attachment in the switch with no effort. Idiom said they had switched vendors and the one I got was not as beefy as the original one.. I hope they went back to the earlier version. But still, I give it and Idiom a thumbs up.. it does what is advertised.. refreshing these days.. actually getting something as good as advertised.. who would have thunk it.
W6OPO Rating: 2007-03-13
Works! Time Owned: 0 to 3 months.
I have had a few audio filters both active and passive, even built one from scratch once. None of them can compare to the performance of the SCAF-1 filter. To get the other filters tight enough to be effective they were on the edge of ringing. They made the signal sound awful. These filters operated in a totally different way than the SCAF-1. The SCAF-1 works by eliminating frequencies above the control knob’s set point. Think of it as moving a sound wall closer and closer to your target signal. The wall is eliminating all sound higher in frequency – that fatiguing noise.

To start the control is set fully CW for full fidelity. Rotating the control CCW eliminates frequencies that are above it allowing only the lower frequencies to pass. The target CW signal is not affected. What is heard are only those frequencies that are in the audio passband below the control’s setting. As you approach the CW signal you find it is standing there all by its self, almost. Sounds lower in frequency than the CW signal will be there but these are usually insignificant. Eliminating all that higher frequency noise significantly improves the comfort and copy of the QSO.

I use it on my Collins 75S-3B with Inrad filters down to 250Hz. But in reality these filters are so good the SCAF-1 doesn’t help much. But an alternative is to use a filter wider then 500Hz and use the SCAF-1. It provides a nice analog variable control and the sound is good.

Same with my FT-1000D with Inrad filters in both IFs. Using a wider IF filter and the SCAF-1 to remove the high frequency noise makes for a nice comfortable QSO. And of course any interfering signals above the CW signal are eliminated along with the noise.

You will have to judge when it is appropriate to invoke the narrow IF filters or use a wider filter and let the SCAF-1 do the work. You will notice a difference. Circumstances will tell you which is better.

I have to mention the quality of the design and construction of this filter. I bought it as a kit because I enjoy kit building. It was a simple job putting it together. The instructions were clear like the HeathKit manuals of the 1960s.

Assembling a kit that is well designed and has high quality parts is fun. The enclosure holes and hardware aligned perfectly including the access hole on the bottom to adjust the trim-pot inside. The package looks great too.
G4WFQ Rating: 2006-12-19
Excellent Time Owned: 6 to 12 months.

Excellent audio filter.
Far better than any fancy add-on DSP filters.
Most useful on CW for narrowing the audio bandwidth and makes the copy less strainful.

Highly recommended.

73 Dave
NJ3C Rating: 2006-12-13
Fun to build and works well Time Owned: more than 12 months.
I bought this filter to go with my IC-706MKII, which is susceptible to shotgunning and picking up interference from strong stations several kHz away despite a 500Hz CW filter. It was impossible to do any contest work at all. The SCAF solved all my problems. I recommend this to anyone with a low to mid-range rig looking to dramatically improve receiver performance.

Building the kit was also a snap. Despite being relatively inexperienced, I had the SCAF-1 up and running in six hours.
WX9J Rating: 2006-10-28
best filter made Time Owned: 6 to 12 months.
After using the SCAF-1 filter with my Elecraft K2, I would not think of operating my radio without it.

Running QRP for most of my operating time, I find that I owe at least half of all my QSO's to the use of this filter.

It makes pulling weak signals out of the noise a pleasure and after using it for sometime, I doubt I will ever add the audio filter or DSP that are made for the K2.

About the only thing better than the filter is the outstanding support that Bob, W9KNI provides with this filter, as well as all the other products he produces.

If you get only one additional item for your bare bones K2, the SCAF-1 should be the product of choice.
W8NF Rating: 2006-02-26
A bargain-priced effect tool for fighting QRM and noise Time Owned: more than 12 months.
I don't keep things that I don't like, and I'm keeping the SCAF-1. I like it.

You see, for HF receiving, I like to arm myself with a collection of tools. The filters in my rig are some of those tools, and so is the noise handling ability of the rig. The SCAF-1 gives me yet another tool. The better a rig is, the less the SCAF adds, but it will still be another tool.

I have two main HF rigs. One of them is Icom IC-735, which I use mainly for backup and mobile. A reasonable performing radio for its time but it was not up to the level of the IC-745, available at the same time. On a crowded band, or a band with a high background noise level, the '735's high PLL phase noise can make the band sound even worse. The standard and optional filters have rather gentle skirts, and the audio circuits add some more noise. The SCAF is outstanding at eliminating much of this noise. Further, the IC-735's "VBT" function shifts the entire passband of the IF filter around - you raise the lower edge of the passband while you raise the higher edge of the passband. With the SCAF added, you can now use the VBT in the rig to adjust the lower edge of the passband, and the SCAF becomes your new adjustable, and much sharper, higher edge of the passband. I have the optional CW filter in the '735, and it's nice, but it's not a sharp 8-pole filter. The SCAF can be used to "doctor" the upper edge of the CW filter and make it razor-sharp.

The SCAF is not just a lowpass filter. It's actually a lowpass and highpass put together. The highpass is not adjustable, but its there, and it removes a "thumping" noise that my IC-735 generates from the QSK circuit on CW. Makes the '735 far more pleasant in QSK.

My other rig is a Kenwood TS-850SAT. This radio's receiver lands on the top ten list of the best receivers ever tested in the ARRL lab. Kenwood built this rig with a tremendous amount of gain in the RF, IF and audio sections, and it actually delivers MORE audio noise to the headphones than my IC-735 does. The built-in audio lowpass filter of the Kenwood is barely functional. I find the SCAF essential on this rig if I'm using headphones, to take out the hiss above 3kHz that the rig's audio circuits generate. When I first got the radio, it had cascaded Kenwood 500Hz CW filters which were OK, but I felt the need for the SCAF to give that final upper edge to them. I have since replaced the Kenwood filters with Inrad 400Hz CW filters, and this has been a big improvement. The SCAF is still needed to clean up the final hiss in the audio.

However, cascaded 400Hz CW filters are great when I've zeroed in on the station I need and am ready to pounce. In casual CW ragchews or contesting, I want something wider, like about 1kHz. If you have optional CW filters installed, you can't put in two SSB filters, only one. So you're stuck with one crystal filter and one stock ceramic filter, giving you the ability to have one sharp edge and one dull one! So I use the dual-slope tuning feature of the radio to set the crystal filter as the bottom edge, do my best with the ceramic filter for the top edge, and then do a final clean-up with the SCAF. The result is a very nice 1kHz bandwidth, useful for hearing all the stations in a pileup or while contesting. I can always punch up the 455kHz IF Inrad CW filter if I need to hear that one weak one, and then punch back to the SSB filter when I've worked him.

I've used a variety of radios at lots of club field day operations, and I agree with comments made by KX0R earlier. The SCAF has a lot more advantages if you have an older rig. Today's "super radios", particularly the Ten-Tec Orion, may not need the SCAF. The SCAF would always be able to add just a few more poles to the filtering, but the Orion, with crystal filters and DSP, is probably pretty darned sharp and I'm advised that they have implemented a good tracking audio lowpass, so their radio does not generate enough audio hiss to worry about.

But you will have to determine your sensitivity to these things. If you listen exclusively to SSB ragchews and you actually prefer a loudspeaker in a non-anechoic room, you probably don't even notice the difference made by going to an 8-pole crystal filter. You may find the SCAF uninviting. You may not hear, or care about hiss. But even in ragchew situations, I have found it useful. Just this evening I had a ragchew with a buddy on 75, and the SCAF was just right for eliminating a tuner-upper's carrier that my rig's notch filter did not quite take care of.

As I said at the top, the SCAF is another tool to use with an HF receiver. You have to determine whether you're a discriminating enough operator to need the added tool. At about $90 kit form, it's less expensive than any add-on crystal filter that I'm aware of.

The SCAF-1 is such a valuable tool that it's not going in the toolbox, it's staying right on top of the radio so I can use it any time I need to.
KG4EDA Rating: 2005-11-22
Top Notch Product Time Owned: 0 to 3 months.
I really didn't figure out how it worked until I built it. But basically, SSB only needs an audio bandwidth of about 4 KHz, and CW, much less, but most mikes, audio amps and speakers are usually made for "high fidelity." Stereo speakers for example are often used in ham radio, but they have very wide bandwidth, and that is not a good attribute for SSB or CW. There's no point in having a speaker that covers 20 Hz to 20KHz when almost all of that range is noise.

The SCAF is a sharp cut off active filter. The single control knob varies the width of the filter. I think it's probably best for CW, but I also use it for SSB and it helps get rid of foreign broadcast and other noise.

The kit is very well put together. The PCB is top notch (pun intended) with plated through-holes, etc. Not just some board some guy made in a garage.

The instructions were not hard to follow--I built it during a couple of QSO's.

The kit contains all the parts needed, including speaker, phone and power jacks. All you need is solder, tools and a power supply (12V).

You may also need a magnifying glass to read the numbers on some of the parts because humans don't assemble electronics anymore so parts are getting much smaller--especially the color codes and printing. Getting the LED in is a little tricky mostly due to the fact that parts are really designed for machine insertion.

It's a true high-performance audio filter at a very low price in an easy-to-build kit.