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Reviews For: Idiom Press/Ham Supply SCAF-1

Category: Filters, Audio: (DSP and others)

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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
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
AD9DX Rating: 2013-08-13
Neat little toy Time Owned: more than 12 months.
I bought my Scaf second hand but unused at a hamfest. While I did not "need" it, I am a bit of a filter nut trying to get that last bit of an edge out of my system. I have plenty of filtering options with my K3 and its optional 200hz roofing filter but what the Scaf does is take a bit of the edge off. It also in some situations gives signals a bit of "pop" bringing it out from the noise floor.

Has this filter gotten me any new ones that I wouldn't have otherwise? Absolutely not! What the filter does do is make the time on the air more enjoyable. And less fatiguing, something the K3 desperately needs.
AD4C2006 Rating: 2013-07-10
One great filter Time Owned: 0 to 3 months.
For years I have heard about how good this SCAF-1 was but never had a chance to own one.
Recently a guy on put one for sale for a decent price already assembled and made my mind,tonight I have it conected to the headphones connector of my new FTDX-5000MP and after listening for an hour I think there is only one word to express my impression: WOW !!
Its amazing how well this filter works, either on CW or SSB the filtering is very effective, I have been able to notch very strong stations just 200 or 300 Hz away from weak ones on CW and just 1.5 to 1.8 Kz away on SSB, its just like having a very well design DSP in your hands, so now with the help of sharp roofing filters and this very selective audio filter I have a very good sharp receiver. I don't even need to use the Contour/Audio filter control of the 5K.
I have to congratulate the designer and builder of this SCAF-1 because this circuit is very effective.
It not only narrow the audio passband but also cuts down the band noise to the point that look like we have the powerful effective "DNR" from the 5K.
I also tested with the K3 and it works terrific with that radio as well.
Its a keeper as a great accesory for the station no matter how old or new be your radio.

K6WHP Rating: 2013-05-01
Unit So-So; Service Terrible Time Owned: 0 to 3 months.
I am compelled to weigh in with a less-than-sunny evaluation of this product. I had written a previous review (removed by based upon my experiences with the Idiom Press people and their failure to not only not deliver their product BUT TO REFUSE TO ACKNOWLEDGE MY ORDER AND RESPOND TO E-MAILS AND PHONE CALLS OVER A SIX-WEEK PERIOD. (I was not alone in travails like these; another ham had similar contemporaneous problems and likewise cancelled his order.) I can understand the previous review being removed because it was not about the product per se.

Anyway, aside from the fact that I did not have my order honored and ultimately cancelled with them, I bore the actual product no malice. In fact, because I was able to pick up one at a swap meet -- one requiring repair work, by the way -- I want to now write of my experiences and offer caveats to anyone contemplating purchasing the product or the kit. Here goes:

Firstly, the unit I got at the swap did not work. Attempts to find a manual were fruitless until a fellow ham graciously sent me a copy of his. Upon commencing the repair work I noted that there were radical differences between the manual and the actual unit I had on hand. While the board may have been accurate per the manual, the front switch was not. My unit had a DPDT with six tabs and the manual had nine tabs. The wiring on the unit I had bore only the remotest resemblance to the wiring in the documentation.

Please note that the instructions were published in 2006 and there was an addendum of corrections outlining a means of modifying the LM386 circuitry so it would perform better. (I think circa 2008) It was a very complex series of "four instructions up from the bottom change x to y" steps and occurred to me that perhaps the owner should have REWRITTEN the original to reflect the changes and tied them more tightly to board/kit revisions.

When I finally got my unit working, I was pleased -- BUT NOT IMPRESSED -- with its performance. The circuit is merely a low pass filter comprised of the two SCAF chips driven by a 555 timer. It ain't rocket science. Frankly, the NEScaf kit by the New England QRP club ( and the HI-PER-MITE ( offer products with as much promise, are very well supported, and are much more reasonably priced than the Idiom Press SCAF-1 unit.

Finally, previous "I bought mine several years ago, built it, and love it" reviews might be nice and fuzzy and heartwarming but you will be spending anywhere from $95 to $130 for one of these things and, if so, you had better be prepared for

(1) At least six weeks of being ignored after your order is taken.
(2) The prospect of a kit whose instructions are ambiguous and possibly out-of-date.
(3) A pathetic record when it comes to support and service.

The 2 is for the performance of the unit. Were I to rate the overall experience with Idiom Press with respect to the SCAF-1, it would be zero.

Color me not impressed.
WB0FDJ Rating: 2013-04-16
Does a great job Time Owned: more than 12 months.
Purchased as an assembled unit several years ago. I am currently using this on an old TT Argonaut 509. Completely eliminates the high frequency hiss and white noise, making copy much less fatiguing. Signals which were buried become copyable. For older rigs that lack the newer features this is a very useful accessory and I highly recommend it. It's small enough it can sit on top of my FT-817 easily. Simple to use.

Back when I ordered mine I waited a long time for delivery, then sent a polite email inquiring about my order. I received a reply that basically said, "we are behind, sorry you had to wait so we will only charge you the kit price". I'm still impressed by that.
VR2ZXP Rating: 2012-05-04
All things perfect!! Time Owned: 0 to 3 months.
1) Very easy to assembly. 2 days should be enough.

2) Components are in normal grade but much better than those China brand kits.

3) Cosmetic is very good. Looks smart and much better than those MFJ products.

4) It's really helpful to reduce the noise in SSB & CW mode. The roll off is very sharp. I can't found out the difference between using the most narrow bandwidth of this filter to listen the morse code in CW with 600Hz IF filter or in SSB mode with 2.4kHz IF filter.

5) When switching on the power, a very loud "Po" noise will be heard but it is acceptable on this kind of low cost product.

General speaking, if you want to pay higher cost to buy DSP filter like Timewave, I suggest you to save the money and try this little box first.
KJ6ETL Rating: 2012-04-19
Good product, no support Time Owned: 0 to 3 months.
I have built only a few kits and am by no means a true ham with the “knack”. To me building a kit is like putting a puzzle together with at the end a piece of equipment that I can actually use.

The kit arrived quickly, all parts were counted for. A professional made printed circuit board a case are almost a guarantee to end with professional looking device. The manual is well written but it certainly could use a few images to shed a light on some parts of the construction. In particular the wiring is very hard to follow. Further I made a mistake by soldering the diodes in exactly the wrong directly as the should have been. This leads to my main complaint of this kit. There is no support. During the build I wasn’t clear about the diodes and despite reading the instructions carefully I was not 100% sure and decided to pause the project and call Idiom Press. I left a voicemail and have yet to receive a call back :-(

After I connected all the wires and turned the filter on I could not hear any difference in the audio. I started to look for clues and verified all the connections. In the hope that an expert might spot my mistake(s) easily I send a number off pictures to Idiom Press in the hope to receive some support. Until today the email has remained unanswered :-(

I ended up removing the circuit board from the wiring and started the diagnostics with a minimal system set-up. It turned out that the fault was on the circuit board and not the wiring. Since I had trouble understanding how the diodes were supposed to be mounted I painfully extracted the parts and put them back in the reversed direction. Voila it works

This filter does a great job cleaning up CW signals. Together with the 250 kHz narrow CW filter I can easily decode signals that where otherwise very hard to detect. On SSB however the effect is less noticeable.
GM0WNR Rating: 2012-02-10
Great little bit of kit. Time Owned: 0 to 3 months.
This is one of these pieces of kit that, once you've got it, you can't remember how got by without it! Firstly, the kit is very easy to put together, with very well written, clear, step by step instructions. If you are careful and take your time you will end up with a very neat looking addition to the shack which works first time, as mine did. A user manual is really not needed as there are only 2 controls on the front of the unit, and one of these is the on/off switch! Basically, regardless of mode, you just turn the "width" controller till you get a pleasant sounding result, whether that be SSB or CW, which is my favourite mode, and in this mode, the filter excells. In my humble opinion this filter is as good as any I have tried, and I have tried a few, including a DSP filter by MFJ, an audio filter by Diawa and a couple of Datong FL-3's, remember it is not a crystal filter, but it does not claim to be, it does a very good job of filtering out unwanted signals. I would rate this as a must have for CW ops. All in all, a great sounding, useful, and, most importantly, a nice looking bit of kit that gives you the satisfaction of knowing you built it with your own fair hand.

KG7RS Rating: 2012-01-13
Attention Boatanchor Ops! Time Owned: 0 to 3 months.
Hi Folks,

I've been aware of the SCAF-1 for some time but doubted the effectiveness of an audio filter to improve CW selectivity. During a recent kit building binge, I decided to try one for use at my vintage station with a Hammarlund HQ-160 receiver. What a difference! The HQ-160 isn't noted as a selectivity champ but does have a very effective slot (notch) filter and a Q-multiplier which can provide decent selectivity when properly adjusted. Still, it requires lots of knob twisting and nudging to attain usable CW selectivity. With the SCAF-1 switched in the difference is profound. The passband is quickly and easily narrowed with one knob. Signals really stand out and copy is considerably improved. Very strong, very close signals may still cause desensitization - after all, this is only an audio filter, but I've found the HQ-160's slot filter placed right on top of the offending signal takes care of it. Using the slot filter without the SCAF-1 still allows the offending signal to be heard; with the SCAF-1 and notch, the offending signal is gone. Most often, the SCAF-1 alone is all that's required to provide the necessary selectivity for single-signal reception.

SSB readability is also greatly improved at the widest setting of the passband knob on the SCAF-1. The HQ-160 passband is so wide that just switching in the SCAF-1 makes a substantial difference in readability.

I'm thrilled with this product. I love to operate vintage equipment, especially on CW, and the SCAF-1 makes all the difference. Best of all, I can use it to clean up the selectivity of just about any old boatanchor receiver I may want to play with. In combination with the HQ-160 with its slot filter, the result is a very competent CW receiver which was only average before the SCAF-1 was installed. The SCAF-1 removes much of the suffering of trying to copy CW with less capable boatanchors such as an NC-88, SX-99, etc.

My SCAF-1 came as a kit which required about 6 hours to assemble including inventory & sorting/organizing the parts. Assembly instructions are well written. The kit uses several discrete wires connecting the DPDT toggle switch, passband pot and the audio input & output jacks which slows down the building process a bit. Otherwise, assembly is straightforward and shouldn't pose any difficulty. This would be a good kit for a first-time builder. The kit includes a very high quality two-piece cabinet which is pre-drilled and nicely labeled on the front panel. The rear panel has no labels oddly enough. Audio input from the radio is an RCA jack. There are 1/4" and 1/8" output jacks and the builder has a choice of which is used for a speaker or headphones. The output jacks may also be wired as stereo (3 conductor) or mono (2 conductor) plugs. 12VDC power input is provided through a 5.5 x 2.1mm standard coaxial jack. I used a 12V 1A regulated wall-wart from Jameco which uses a built-in 3-terminal regulator IC, ample filtering and provides a stable 12.6VDC source. Otherwise 12-13.8VDC station power may be used. The unit is very small and easily integrates into an existing setup.

If you're a CW op and love to play with vintage/antique gear, I hope you try the SCAF-1. I can see how this product may not make a profound difference when used with modern equipment with already good selectivity but with vintage equipment, the result is astounding.

73, John, KG7RS
HFHAM2 Rating: 2011-11-25
Okay but not Great IMO Time Owned: 0 to 3 months.
I wasn't as impressed as everyone else seems to be with my SCAF-1. Yes, it works okay, but doesn't go very narrow for CW work. For SSB, if you adjust it narrow enough to make a difference, it makes the voices muffled (which I hate listening to).

Maybe I was spoiled with the SCAF on the SGC SG-2020 HF transceiver which would narrow right down to 100Hz for single signal CW copy (fantastic), but the SCAF-1 doesn't go that narrow.

After a month or two of using it, I sold it and bought a 250Hz crystal CW filter instead (which did a far better job on CW).

The samples on the Idiom Press web site sound great, but I didn't get results as good as those.
VE3GNU Rating: 2011-02-07
Perfect Time Owned: 0 to 3 months.
There are a goodly number of Audio-type filters available, but after considering, and then discarding some of the candidates I finally, and happily settled on the Idiom SCAF-1. It's a perfect addition to my Ten Tec Argonaut V; it does exactly what is advertised and delivers the kind of listening comfort, that I feel, is welcome in today's DSP environment. As well, the EHAM REVIEWS were instrumental in acting on my choice, and if I may suggest---anyone with a DSP rig might want to consider this option for a more relaxed and pleasurable listening experience. I might add that this was my third dealings with Idiom Press---great products, great service, and a great company.