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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.
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
NC3S Rating: 2003-03-03
Performs as Advertised Time Owned: 0 to 3 months.
Really cuts the White noise that would cause my ears to throb after about 30 minutes of headphone use with my DSP rig. This kit is probably not for everybody, but those people that have the headphone ear fatique problem will appreciate it. I work almost exclusively CW with head phones so I can't say too much about it on Phone, but casual listening to SSB is improved to my ears too. I don't want to forget mentioning that it improves the raspy sidetone of my rigs audio.

The kit goes together easy and is mounted in a solid attractive enclosure (similiar to their keyer kit).

Some minor areas for improvement would be a front mounted headphone jack and maybe labels for the controls and jacks.
W0SR Rating: 2003-03-02
Great Performance in a Compact Package Time Owned: 0 to 3 months.
A few years ago I purchased a audio filter called the Super SCAF which was manufactured by Aftronics, Inc. It was an impressive unit and it found a lot of use my shack. Unfortunately, the Super SCAF has not been available for years. I'm told if you are lucky enough to have one keep your fingers crossed because the scaf parts used in it have been completely unavailable for some time. And, although the Super SCAF performance is outstanding, it is large and very inconvenient to use because of the stiff thumb-wheel switches
used for bandwidth selection.

At one point I tried for more performance and purchased a MFJ Tunable DSP Filter. This proved to be a lot more pain than it was worth and I went back to using the Super SCAF.

Recently a friend mentioned that a new SCAF audio filter was on the market and he suggested checking it out at the Idiom Press web site
( It sounded great and soon an Assembled & Tested SCAF-1 arrived. I decided to test it by hooking it up in series with my old Super SCAF. I was impressed immediately by the small size package making it easy to slip in under my transceiver where I can conveniently control the In-Out switch and the knob which selects the bandwidth. After fighting the thumbwheels of the Super SCAF, the simple tuning knob of the SCAF-1 which adjusts the bandwidth is a joy to operate, allowing you to easily match the selectivity to the operating situation.

Having the two filters in series allowed me to easily switch between them and I made over a hundred tests on both SSB and CW. I was unable to see ANY difference in performance under any conditions. The little SCAF-1 is amazing. So for me, it is time to retire the old Super SCAF and enjoy the convenience of the new filter.

I use an audio filter on both CW and SSB. It not only tailors the bandwidth of the lightweight headphones I usually use, but allows me to dig out
signals more easily in heavy QRM, even when using the transceiver's narrower crystal filers. My QTH usually has a lot of power line noise and the
restricted audio bandwidth from either of the SCAF filters makes for a lot more pleasant listening, even if there is no QRM.

I highly recommend the SCAF-1 for anyone who would like to hear improvements in their HF listening.

W0VX Rating: 2003-02-14
Excellent Performance, Low Cost Time Owned: 0 to 3 months.
I bought the SCAF-1 as a kit to save a few bucks. It took me about 4 hours from the time I opened the box to when I had it operational. All of the parts except the connectors and controls mount on a drilled and screened 2 1/4” x 3 1/4” glass epoxy PC board. The case is heavy duty aluminum which is nicely painted and screened and matches the LogiKit CMOS-4 keyer. The assembly instructions are well written with Heath Kit like check-offs for each step.

The SCAF-1 is a variable frequency low pass audio filter. The simplicity of operation combined with its effectiveness is what makes it so attractive. An IN/OUT switch and a pot to adjust the low pass filter’s cut off frequency are the only controls. From a purely practical standpoint, the cut off frequency is what you almost always want to adjust to optimize reception. In many respects the philosophy of simplicity of operation reminds me of my old Collins S-Line.

Simplicity is good only if it is also effective. The SSB performance improvement on my backup HF rig was remarkable. One of the things I immediately noticed when turning on the SCAF-1 was the disappearance of the white noise and hiss I was used to hearing on that receiver. It had the effect of putting high quality filters with sharp skirts in the rig. Signals that were out of the desired passband just disappeared.

CW performance was exceptionally good. I like to copy CW at about a 500 Hz tone. Setting the cut off frequency to near the 450 Hz minimum virtually eliminated all audio above 600 Hz and the fatigue that comes with it. While I didn’t measure the claimed 96 dB per octave roll off, my listening tests confirm a brick wall filter.

In addition to lower cost, the advantage of the SCAF over an add-on audio DSP for QSK CW is zero processing delay. The add-on audio DSPs I have tried all have varying degrees of signal delay. That makes running QSK with an add-on audio DSP difficult at best. The SCAF-1 exhibits none of this delay.

At $90 the SCAF-1 provides a remarkable performance improvement for that non-DSP rig.