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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
K1RI Rating: 2019-02-22
Logged 3 new ones Time Owned: 0 to 3 months.
Put my new SCAF-1 in line about 30 days ago. Is connected to the ICOM IC-7610. I picked up 3 new CW band fills thanks to the SCAF-1. The 7610 did not hear the stations however the SCAF-1 did and I logged the contacts. Having obtained Honor Roll and now getting band fills, I bought the book "The COMPLETE DX'er" by W9KNI. He mentions the SCAF and peeked my interest. When it pulled out CW my K3 or IC-7610 could not.
KG4LLQ Rating: 2018-02-13
SCAF-1 is "OK" but not great Time Owned: more than 12 months.
I've had my SCAF-1 for over 10 years. Building it was no big deal. For a filter its "fair" but gets no prizes. Here's the problem: it's an audio filter so annoying signals that infringe on the tuned signal can still get through and affect the quality of the filtered signal. This is an inherent issue with audio filters: the transceiver/receiver still lets the adjacent signals to get through and if they're strong enough they affect the signal (CW) you wish to copy. Nothing can eliminate adjacent signals that you want to remove like an IF filter. That's why I rate the SCAF-1 as just "OK".

Earlier 5-star review posted by KG4LLQ on 2013-02-18

I built & have used the SCAF-1 since 2002. It is an excellent alternative to IF CW filters optioned in low-end HF transceivers. I use mine exclusively with an IC-718 and find I can "weed out" most any adjacent signal. If compared to a 500 Hz IF CW filter I recently installed in my IC-703; I'd say the SCAF-1 is an excellent buy. It's fun to build and performs as stated.
N6BIZ Rating: 2017-12-16
Great Time Owned: more than 12 months.
I have two
They are great
K1PJR Rating: 2017-02-26
Very nice Time Owned: 0 to 3 months.
Assembled on Saturday. Took my time. Connected to the rig and turned it on. Worked! I have a TS590 and this is a nice addition. I operate SSB and it's nice to flip on switch and turn the knob until you're happy with the signal. Fun project and is very useful. A keeper in my book.

KA1IS Rating: 2016-12-11
good low pass filter Time Owned: 0 to 3 months.
This product is an audio low pass filter.

If you have a shortwave receiver or transceiver with wide filters - that is, greater than 1200 Hz or so - this filter will really improve selectivity.

If you have a recent ham transceiver with decent CW filters, it won't make much difference. It will reduce hiss or other stray high audio frequencies, if that is a problem you are trying to solve.

Excellent build quality.
AE9DX Rating: 2016-12-11
Excellent product! Time Owned: 0 to 3 months.
I picked one up on e-bay for $40.00 and have never looked back. I work mostly SSB with some CW and even with a modern rig like the Icom 7600 or my Pro-3 it does what it's supposed to. With the easy adjustability of this little gadget, you can take out the majority of the back round white noise while not cancelling the signal you are trying to hear. It does what it's supposed to!
KM6AXC Rating: 2016-07-15
Really Powers in the CW signal Time Owned: 0 to 3 months.
I am a 72 year old newbie at this stuff so I thought I'd pass on this tidbit for other non-tech guys. First, the product probably deserves a "great" rating but I as yet don't know enough about what I am doing to fully appreciate the product:) All the reviews below should give you enough info on how it performs, I'll just give you a hint on how to improve the instructions/device hook up. The instructions say in part ".......cut one end off and then solder on the connector that is correct for your radio". NAW!! Just go to Radio Shack, buy a stereo cable and an adaptor that takes your stereo plug and magically transforms it into an RCA plug. Also, for some reason (my lack of knowledge perhaps??) if you have headphones on when you hit various switches, be aware that a loud "pop" will occur and may hurt your ears. For me, I have learned to turn the receiver gain down and then push other buttons. But a small thing for the signal improvement the product produces. If you know how to eliminate the pop, please let me know??
KA8DDT Rating: 2016-05-30
Outstanding audio filter!!! Time Owned: 0 to 3 months.
I just assembled my new SCAF-1 audio filter from and it’s just as exceptional as the company and reviewers said it would be in sorting out weak signals in big pileups.

I got back into ham radio and CW two years ago with a new radio and antenna, but the internal 500 Hz audio filter I bought for my new radio and my old stand-alone audio filter simply weren’t up to the task.

Online, I found the reviews touting the SCAF-1 audio filter. But unfortunately, the SCAF-1’s manufacturer, Idiom Press, had gone out of business and, which acquired Idiom, had sold all of its SCAF-1 units.

But ordered up a new batch of SCAF-1 units, which went on sale in May.

The filters come in two versions: a kit you can build ($108.95) or an assembled and tested unit ($148.95).

I bought the kit, which arrived quickly, and assembled it in two evenings. I’m a bit rusty on electronic kit assembly, so the company sent me full color .pdf to replace the black and white photocopied instructions that came with the kit. The color photos were a big help. The instructions coordinate perfectly with the component numbering printed on the circuit board.

I got bogged for a bit wiring the rear panel jacks, but after carefully re-reading the instructions, I connected everything perfectly and the unit fired up on the first try.

What I love about this unit is its ability to filter out unwanted radio signals. Unlike my old external audio filter, this one eliminates headphone hiss and makes ham radio and CW more fun.

The company’s website says the SCAF-1 works just as effectively on voice. has a demonstration video on its website.

K0KZO Rating: 2016-03-13
Very Useful Time Owned: more than 12 months.
I built one a several years ago then stowed it away when I got an FT-950. I recently put it back into service on the R75 receiver and it works great. While designed mostly for CW, it works great to clarify signals on SSB and even on AM. I ding it a point on ergonomics. I recommend a front mounted headphone jack. I added a headphone/speaker toggle in the front, which was an easy mod.
AF2DX Rating: 2014-05-17
It does the job but........... Time Owned: more than 12 months.
Does not come close to the NE-QRP CLUB CW FILTER.
I just did a side by side comparison with the Idiom press SCAF filter and the NE-SCAF club filter
The Idiom press does a good job but the NE/SCAF club kit filter comes way ahead and the price for the kit is about 1/2.
I think the latest kit that the New England put out was using a different chip and gave it a bit less hiss but i'm happy with mine

Earlier 5-star review posted by AF2DX on 2007-11-13

Well, I guess it's my turn for input on the Idiom press SCAF-1 filter.
After a day of frustrations and QRM on the band,I decided to turn on my FT-857-D only to see that the roaring sound was still in the phones.
I tuned up my indoor MAG LOOP and I really expected something like an S-8 or even higher due to the loudness of the QRM.
I'm not even sure if it's band conditions, my apartment building or both.
Well, there was not much activity on the band so I tuned around and I heard a very, very week station calling CQ.
I figured this was a super opportunity to test the SCAF-1 filter.
Before I go on, the person I spoke with did say I may be better staying with the NE/scaf filter unless I wanted a better looking box.
But I want to eliminate any and all noise if I can so I went for the factory built unit.
Getting back to that unreadable station I tried the SCAF-1 filter and I tuned that knob and I perked up that station to where it was just above the noise and now able to copy a very weak but readable CW message.
I kicked in my CW filter, a Collins 300 Hz mechanical type and lost the station.
A slight turn of the knob clock wise on the SCAF-1 and the station was back and sounded more crisp and just a tad louder
The QRM that sounded more like a rore was now much deeper in tone and seemed much smoother and the CW was well above the noise and I had 100% copy.
Also this was done with all noise reduction features OFF except for the CW filter.
I have 2 857-D rigs and keep one at my G/F's house.
She has a constant buzz there and it's not from her place.'It's a dimmer switch from her neighbor next door.
I first tried all the noise reduction features on the rig and I got rid of most of it,.
I turned off all the noise reduction features,turned on the SCAF-1 and eliminated the buzz 100% GONE.
Just tonight I tried my rig at home and I used the built in DSP and the CW filter and they removed the noise by about 50 %
I turned off the DSP features and used just the CW filter and the SCAF-1 and I heard several stations from Europe on 7.017.5.
I turned off the filter and I heard NOTHING.
To me this makes my cheap 857-D sound more like a $2,000.00 rig.
If you like to copy strong CW that blows through all QRM then you don't need this.
If your a QRP & a DX hound like me and are persistent at bagging that station then you need this SCAF-1 because last night when everyone said 40 meters was shot down I hunted around on the extra band and I got one more DX station logged.
I worked OM3SCM and he was running 40 watts from a home brew transmitter.
It's the best investment I ever made for my ham gear.
I was so impressed with the performance of the SCAF-1 I even called Idiom press and let them hear how well it worked at my QTH with with all noise reduction features OFF on the 857-D.
It also beats playing with all those knobs on that MFJ noise eliminator that also needs another antenna to work and that doesn't help the hams who are antenna restricted