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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
KA3NXN Rating: 2004-06-01
Awsome Time Owned: 0 to 3 months.
I took an afternoon to assemble. With the instructions included you can't go wrong, if you read them carefully. The first time I hooked it up it made worlds of difference. I am using a 706MKII with all the filter options available form Icom and I was till not staisfied. With this little baby installed listening to the "Rotten Apple" group on 7.238MHz is much more pleasant. I highly recommend this filter.

Excellent procuct & super fast service.

KC5NWS Rating: 2004-05-28
great filter Time Owned: 0 to 3 months.
Just hooked up the scaf-1 filter this morning and I am really impressed. Its the best audio filter I have ever used. Now my scout will get a lot more use with this easy to use filter in line.
WF7A Rating: 2004-02-27
Helpful Hint When Building the SCAF-1 Time Owned: 0 to 3 months.
I forgot to add in my review below that the resistors and diodes are vertically mounted to the circuitboard so you'll need to bend the component's top lead over then down so the part will insert into the board correctly.


Don't use your fingers to bend the lead: use the tip of a needle-nose pliars to grip the lead just above the end of the component, then use your fingers to bend it downward. The reason why you want to do it this way is that if you just used your fingers, you would risk cracking the frail junction between the resistor/diode body and its lead, thereby allowing oxidation and/or corrosion to occur within the component.


Earlier 5-star review posted by WF7A on 2004-02-24

Howdy from Coeur d'Alene, Idaho, everybody!

Last week, I ordered a SCAF-1 outboard audio filter from Idiom Press ( and thought I’d post a review here now that I’ve finished building and testing it. So, pour yourself a cold one and read on.


The SCAF-1 is basically a tunable, low-pass audio filter. (For a detailed explanation of its function, go to the link above.) I used to own its predecessor, the Super SCAF—a band-pass filter--and I was very pleased with its performance…though its thumbwheels were literally a pain to use. I was foolish to sell it long ago, but when I found out recently that it had a successor I just _had_ to buy one! I ordered it late last week it arrived within a couple of days—GREAT customer service there, Bob!

So, with the parts sorted in their muffin pan cups and a 150-Watt soldering gun in hand…

Just kidding!

My Ratings System

My ratings go from 0 (P.O.S. Extraordinaire) to 10 (Terrific!). So, here goes:

Customer Service: 10

There was an on-line ordering problem [damn those firewalls and anti-pop-up programs where I work!) and I really thought it would take a couple of days to push my order through because of e-mail turnaround times, but Bob at Idiom was extremely gracious and expedient—he returned my call very quickly and got my order out the same day within hours after I rang him.

Instructions: 9

They’re very good, but I think that with a few illustrations and/or pictorials, you wouldn’t have to re-read a few paragraphs to ensure that you’re orienting or placing the components correctly. This would be a benefit for novice kit builders.

Components: 7

Physically, the circuitboard and the included parts are top notch, but having put together more than a few kits in my time (I made amateur radio history when I put together a HeathKit keyboard keyer in one afternoon…during my honeymoon) I noticed a few quirks that slowed me down a bit:

1) The kit includes two DIP sockets for its 8-pin ICs, but there are six ICs, so why only two? I would’ve included all six with the kit.

2) The circuit has a happenstance numbering scheme for its component layout. Convention in the electronics industry dictates that you number components in sequential order much like reading a book, so say you have six resistors to stuff into the board on four different “lines”, or areas—they’d be numbered on the circuitboard thusly:

R1 R2
R3 R4

Not so on the SCAF’s circuitboard, so I had to spend a bit of time searching the board and/or component layout sheet repeatedly for a component’s location before it could be stuffed.

3) Aside from a few editorial edits, I would change the instructions so that the diodes would be stuffed first instead of the resistors. As most astute kit builders know, you should use a heatsink clip between the component’s base and the top of the circuitboard to protect heat-sensitive, junction-type components (i.e., transistors, diodes) from heat damage while soldering from the other side of the board. In the SCAF’s case, the board is pretty populated by the time you start soldering the diodes so there’s no room to apply a heatsink clip.

4) The hole for the 1/4” phone jack was too small to fit the jack’s flange into the chassis wall. As drilled, the hole allowed a noticeable bit of play for the jack’s barrel to slide around (with its flange against the inside of the chassis), so I’m not sure what the story is with that. I took a reamer to open up the hole so it would accommodate the jack’s flange, then tightened the part in place. I think it looks tidier this way than if I hadn’t enlarged the hole.

5) Call it personal preference, but I’d rather wire jacks, switches and plugs before they’re mounted in the chassis instead of afterward—it makes for much easier soldering of the parts because you don't have to get creative with the soldering tip in a tight place.

Assembly Time: 6 hours

Okay, here’s what happened: it really only took about four hours to build the kit, but aside from a trip to Radio Shack for the IC sockets mentioned above, I blew over an hour’s time looking for a couple of dropped resistors that I thought fell into the thick carpeting around my desk. (Yeah, I know--don’t say it.) After all that time searching for them I happened to spy them hiding under a part in the parts dish I had for the kit. D’oh! And you wonder why they call it _amateur_ radio…

Assembly Hints:

It sucks getting old…ugh. (Growing old isn’t for sissies, I tell ya.) I used to work with SMT stuff when it first came out, but now…soldering discrete components into those tiny holes is a major challenge for my aging eyes…and the holes in the SCAF-1 are tiny.

To ensure that solder flows through the board fully, here’s a suggestion: use the point of a toothpick to dab a tiny bit of solder flux into both sides of the board’s holes before you solder the parts in place. (Since the holes are tiny, you don’t want to apply heat too long to ensure the solder flows through the board.) Use flux remover to remove the flux residue after you’re done soldering.

(In the instructions, it says NOT to use water-based flux. Why, I don’t know…so if anyone can enlighten me about that I’d appreciate it.)

When you’re done and have checked out the board for cold soldering joints and such, protect its foil side by spraying it with either a coat of conformal coating or, if you’re a non-conformist (non-conformalist?) like me, use an aerosol hairspray, instead.

Performance of Filter: 110.3

I couldn’t be more pleased--I LOVE this filter! It works as advertised and for people who are hard of hearing like me, it makes operating CW a lot less fatiguing. The filter also works well on SSB, but it really shines when using it for CW reception. Now if only it would tune out my boss when he's talking...

Overall rating: 10.0.

Okay, you’re asking why am I giving the filter a 10 if I had the issues above? Simply, if you buy the filter assembled you’ll have a “10” on your hands. It’s an excellent product that does one thing and does it very well. At first blush, the price may seem kind of steep, but hey--the SCAF-1 will provide many years of use and makes hamming a lot more enjoyable; it's worth every penny.

Your favorite Spudnik...
Rich, WF7A
WB2RHM Rating: 2004-02-25
Eliminates noise and fatigue Time Owned: 0 to 3 months.
Just got one and added it to my TS-440S/AT setup. Wow! What a difference in the ability to listen for hours without 'white noise' and 'tune-out' splatter.
This is one of the best price performer add-ons you can add to your rig.
FYI- the power supply plug is now in the kit.

There is a warning against using 'power cubes' to supply +12 to the unit. Most Cubes are not regulated, they typically output higher voltage than the label says and then they have hum because they are only slightly filtered.

I found that if you by a +12V 3-pin voltage regulator chip from RadioShack and install it inside the SCAF-1 box, connecting the input pin of the chip to the center pin of the power connector, the ground pin of the chip to the ground pin on power connect and then tack solder the RED power lead that goes to the circuit board to the regulated output of the chip, you then can use a wall cube to power the SCAF-1. No hum in the output.

Good kit, easy to build, works great.

Ben Antanaitis
VK5GX Rating: 2004-02-08
Absolutely Brilliant Time Owned: 3 to 6 months.
I like the idea of adding a personal touch to my station. So, when I saw this kit, I bought it, built it and the flexibility it adds to my old Kenwood TS-820S is outstanding.
The kit is straightforward to build, and worked first time on power-up.
Following my experience with this kit I purchased the Logikit CMOS-4 keyer and use it with the same rig.

Both the SCAF-1 and CMOS-4 Keyer kits are excellent products and represent value for money.
W3ULS Rating: 2003-12-31
New Legs for Older Rigs Time Owned: 0 to 3 months.
Thanks to the previous reviewers, I recently acquired a SCAF-1 audio filter for my Ten-Tec OMNI VI (Opt. 3).

Using the SCAF-1 with the OMNI VI has given the old rig new life on CW. Of course, the OMNI VI starts out with a robust front end, thanks to a 9 MHZ 1st IF and consequent lower phase noise, and it also has very good cascaded filters. Combined with this good start, the SCAF-1 gives the OMNI the kind of filtering flexibility that only came along later--particularly with the Kenwood TS-870 (although the TS-870's front end is somewhat deficient) and the ICOM PROs. (On SSB the Yaesu Mark Vs with their IDBT feature are also in that privileged category, but I think on CW they also could benefit from using the SCAF-1 instead of their built-in CW audio filters.)

Basically, for CW you set the OMNI VI at 1.8 kHz in the 1st and 2d IFs, and narrow that passband at the audio stage with the SCAF-1. Occasionally, you will encounter a strong signal inside the 1.8 kHz passband but outside the SCAF-1's setting. You can see the signal on the S-meter while the signal you're listening to weakens (desensing). So you hit the 500 Hz filter button in the 2d IF and boom--the interfering, (inaudible) signal is gone. If necessary, you can punch in the 1st IF's 500 Hz filter as well.

Idiom Press emphasizes the noise reduction value of the SCAF-1, but I think the wonderful single-knob filtering flexibility is the outstanding feature. The noise reduction is a bonus.

What I have described with the OMNI VI would be true as well of any of the older receivers by ICOM, Yaesu, and Kenwood which had good filtering such as the IC-765.
JACQUES_BELDEROK_EX_WV0Q Rating: 2003-12-01
Fantastic Time Owned: 3 to 6 months.
Easy to build.
Great to use (use with Corsair II)

This device has made my operating much more enjoyable!
Mr Locher is a pleasure to do business with and very responsive to any questions that I sent to him.
Had a CMOS-4 liked it so much this was an easy choice to make.
Tnx es 73
K6LTS Rating: 2003-10-28
Absolutely Super! Time Owned: 0 to 3 months.
I read all the reviews of the SCAF-1 before purchasing the filter in kit form. Checking over the parts list, I found the only thing missing was enough electrons to make 12VDC. You will need to make up cables according to your station configuration.

The PC board is fairly densely populated for its size, and construction takes a leisurely 4-5 hours. Instructions are concise with nothing left to the imagination and a few caveats to steer one correctly in putting it together.

The filter's performance is phenomenal, easily surpassing any other audio filter I've used including DSP. Money well spent.
LA0HV Rating: 2003-08-10
Resurrection of audio Time Owned: 0 to 3 months.
I never liked any audio filter i've used. They seem to just change the noisescope of the sound, not really improve S/N-ratio. Well some dose, but then they "ring" and you are back where you started.
So I did'nt have any believe in this filter when I connected it to my 706mk2g in CW mode at 40 meters. The 1/4" plug directly to a old 8 Ohm speaker and turned the power on. My first reaction was "wooow" .... the 40 meter band changed totally, the feeling of the sound of the SCAF-1 was, that it was just as "sharp" as my 250 Hz filter. And even better, i could adjust it. No white noise, no hiss, no ringing, no fake! It works!
On SSB it really makes DX'ing a bless, turn the knob carefully from 1 to 2 o'clock, dont look at the rig when you do, just close your eyes and listen. Try to switch the filter in and out with your eyes closed. Magic: It really improves S/N.
On FM ... im not kidding :-) listening to a weak signal on a repeater, and the guy in the other end have a low voice and has a AC-humming in on his signal too. Magic: Turn the knop fully clockwise turn on the SCAF-1, noise gone, AC-humm gone and audio improved.

I will get an ekstra SCAF-1 filter soon, with all 'em Rig's in the shack one is just not enough.
Best 73 Peter
KC7MM Rating: 2003-07-01
I'm impressed! Time Owned: 0 to 3 months.
I recently ordered one of these kits from Idiom Press. It went together in about five hours.

I unplugged my trusty Timewave DSP 9+ and installed the SCAF-1. The SCAF will stay connected. The DSP 9+ will enter service in station 2 of my soon to be SO2R setup. Both work well, but I think the SCAF is slightly better. Had I know how good it was on CW, I could have saved myself a lot of money that went into internal filters for my TS-850.

The SCAF does an outstanding job of knocking out white hash and nearby signals. It really is quiet. Twisting it's one knob fully counterclockwise and it is set for CW; fully clockwise and you're ready to work SSB. I haven't tried it on the digital modes yet.

My only complaint is something that I have observed in the DSP unit also. Even with my best attempts at zero beating, there are occasions when these AF filters, once turned on, also knock out the weak signal I am trying to copy. Anyone else have this problem?

I highly recommend this filter. I would certainly buy another if needed.

Dale KC7MM