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Topics - RadioRay

I recently sold my two band MTR2b (Gil's old one) and a YouKits HB1B to buy the tiny MTR5b.  I feel it was a good trade, though the problem with any specialized rig is that it's - well - specialized.  The MTR2b had a great receiver, but due to it's being optimized for CW, it is narrow - great for CW, but not useful for anything else: specialized: only for CW. That's not a mistake; it's a design function and it pays-off in superb CW performance in an insanely small package! 

The HB1B by YOUkits has an adjustable bandwidth, so that you can listen to SSB and AM shortwave (by zerobeating the signal) and you can make it quite narrow for excellent CW reception. That's a huge plus for a prepper or any person who's budget recommends that one radio do more than simple ham CW. The Hb1B series does that and one a very good power budget in a small, lite box.

The LNR Precision solved a HUGE problem by selling MTR 3 band and 5 band rigs commercially, because MTR's were previously ONLY available at random, during limited runs of a few dozen or perhaps one hundred; on-line. How the designer was able to dedicate the time, I'll never know.  They often sold-out before word spread that they were for sale. Remember, a full-time employed person is the one who designed and kitted these previously. Even IF I had his brain; I would not do it - too much frustration. So, LNR stepping in to produce these commercially - Woo-Hoo!.

I have only one gripe: p (and it's an important one) my MTR5b arrived very poorly aligned. The transmit/receive frequencies were misaligned by a few hundred Hz.  In any rig, it's a sign of poor quality. In a CW only transceiver with a nice, tight receiver bandwidth: that is very poor.  The receiver stages were poorly peaked causing the already mistuned signal to be out of the center of the passband, when it sounded like it was at zerobeat, so -  even weaker in the earbuds. The frequency display was off by a couple of hundred Hz as well .

I read the manual and because it's based on the construction manual by the designer, it had full alignment and calibration instructions. After a bit of dial twidling and 'tweaker-tool-time', my MTR is right on frequency ( error measured in a couple of Hz after warm-up) , I've peaked the receiver front ends and this MTR5b (like it's predecessors ) is VERY HOT and nicely selective!

I'm glad that I ordered it, but dissapointed that LNR did not perform a proper alignment - after all, it's not a kit. I am certain that the pressure is ON LNR Precision to make as many as possible, so it's tempting to accidentally make them 'faster-than-possible'. However, the fact is that they brought an excellent - limited run product to full commercial production and it's unlike anything else on the market.

Good on LNR for producing these commercially, but please; make more bench time for alignment and tighter QA to keep this excellent rig performing as it should.

73/72 de Ray

Ps. I just finished some QSO's using my home brew , magnetic loop / Anti-HOA antenna.  When I got to the part about '2 watts on a 9 v transistor battery' the fellow on the other end thought it was hilarious!

I can't STAND it!  I MUST buy the new MTR5b. However, I do not want to cut into my family budget, so am selling other GREAT rigs to cover most of the cost.  Both of my rigs are fully checked, working perfectly and have been in cases when not in actual use.  Prices include shipping.

HB1B Mk3 and SOTAbeams EFHW tuner is sold.  I can afford the radio I just bought!  Both rigs went to good homes.

My Youkits (sold by Vibroplex) HB1B Mk3 QRP rig for 40/20/20/17 & 15 meters, with SOTAbeams EFHW tuner, an EXCELLENT combination for operating from remote environments (or coffee shops...)

It has a built-in SWR meter and is also a general coverage receiver capable of monitoring SSB and shortwave broadcast stations by zerobeating the broadcast carrier. It have the internal LiPO battery, a wall-wart charger.  It is a very good transceiver for a person who wants both a highly portable CW transceiver and the ability to monitor ham SSB and international/national shortwave programming. They sell new for $299 from Vibroplex. I'll sell mine with my a SOTAbeams EFHW tuner for $225, including shipping . You save  ;D  $74  :D and shipping and get the WORKING EFHW tuner as a bonus. . . PayPal please.

I wanted to post it HERE ( and one other private site ) for a few days first.  Please contact me via this site or  w7asa at yahoo period com .  The sooner this sells, the sooner I can order my MTR5b.

73 de RadioRay  ..._  ._

My/Gil's MTR has sold //

Gil's MTR 2 band transceiver/// SOLD // for 40/20.  You've seen it in videos and read about it here.  It's even been used for our skeds, from his coffee shop. Normally, a fine CW transceiver used by a famous movie star like Gil would cost a million dollars (oh - brother, it's getting deep in here...) but I'll sell it here - shipped - for $130. It comes with spare finals (never needed, but Gil supplied them) , 9 vdc power cord , and the digital mode cord Gil made (I've never used digital on this rig - I'm a code guy. ) Yes, this is the model which was designed to do digital modes and CW, but you'll have to do the websearch on how to do it - I B ignit.)  First PayPal gets it. You will be amazed at how excellent this receiver is. This link is THIS actual radio - from a coffee shop to me in Virginia...
Adolph Hitler learns about QRP - the HARD way.

Video Link:

I really didn't think that this would be THAT funny, but one of the posters on another forum suggested it.

>RadioRay ..._  ._
I have - up for sale - my LD5.  It's a very good little rig, excellent filtering and DSP!  However, there is no reason for me to have an SSB capable rig, because I do not use it.  Mine has hardly been used, has no scratches, dents, bullet holes or elephant foot prints on it - runs very well. Amazingly, I've only used it inside. You can respond by answering this posting and/or pm'ing me.

It lists for $575 but I'll sell mine for the unbelievably low price of only $450, shipped in CONUS, in it's original factory shipping box, with all standard accessories. (Including something funny called a 'mike-row-foughn', which I have used once to test the rig , then put it back into the box. "Sounds Great!" is what the fellow said of it's audio.) there is a possibility of a trade for HF gear.

Here is the link to their page:!/LD-5/p/39885476/category=10468544

If no quick action here on RP, I'll post it for more money on the usual ham sites.

72/72 de RadioRay  ..._  ._
After getting to know about magloops by purchasing an AlexLoop (works WELL, BTW) , I have sold it and made a larger loop for the bands from 20 meters down to 60 meters.  Unfortunately, the Soviet surplus high voltage capacitor I ordered was damaged, however, the vendor took care of the situation admirably.  I'd happily shop with him again.

Attached is a picture of the loop at present, while I get the primary loop (feed point) dialed-in  - duck tape and all . . .

The outer loop is 5'3" diameter, made from 7/8" copper Heliax "hardline" that I got as a reel end on E-Bay for far less money than I could buy 1" copper pipe, and it's easy to shape by hand.

The original capacitor arrived damaged, so I used a WW II 'junk' double stator capacitor as a 'butterfly' capacitor so that the lossy rotor contacts are not part of the circuit.  This keeps resistance low and Q/efficiency high.

The tuning capacitor is turned using an old 3:1 reduction drive, Velvet Vernier dial - likely made in 1940-50. This makes finding the SWR dip relatively easy. 

Tune-up is simple:

1.  Peak the RF noise at the desired freq.

2.  Transmit a carried and re-turn the loop capacitor for lowest dip in SWR.

3.  Have fun on the air.

I've been running 5 Watts from the LNR Precision LD5 (which I like a LOT!) with the loop inside of my front room, due to stupid HOA restrictions.  I have been able to participate in my CW nets and people were shocked when they learned that I was running 5 Watts into a home brew loop.

The loop is capable of moderate power levels with the WW II capacitor in there.  There is a limit, because mag loops develop VERY high voltages and voltage can jump across the capacitor plates. My barn-yard math, based on plate spacing, says that I'm good to almost 4 KV, which is right at 100 Watts on most frequencies.  However, 20 - 50 makes more sense.  I hope to try it using my home brew amplifier.

So, that's what I've been doing on this end.  I hope to paint it, cover it with plastic flowers , string it up and hang glass wind chimes and feathers in it, put it in our little garden and declare it a 'Dream Catcher(which , in a way - it IS!)

de RadioRay ..._  ._
This is a review where the only 'test equipment' is a pair of ears and the 'test range' is actual operation of the radio.

Bottom line: An good bargain in a CW (yes, SSB too, but WHY???) HF transceiver.

I'll leave the specifications over on the LNR PRecision page, but the basics are:

40-15 meter operation in CW/SSB (no A.M.)

Rig seems to put out ten Watts at REDLINE. (Why stress the finals for half an S-unit?)

Built in Keyer that works with a straight key too.

S-meter/SWR meter or power out can be displayed numerically or as a bar graph.


DSP (rarely needed, this is a good receiver without it.)

Current drain on receive 350 mA (about the same as an FT-817)

Very good form factor for field work, because it's controls are on TOP, so that you do not need a shelf to put it on like many rigs.


I have not tested it on SSB, but plan to do that, then put the microphone away for when I sell there rig in a few years. (I always seem to do this.)

In actual operation, I have been using this rig with my AlexLoop, small magnetic transmitting loop. I easily reach coast to coast, taped code with SOTA guys on mountains, even listened to TAPRN voice net Sunday on 40m SSB using the loop and had fair to good copy on the net, though I am 2500 miles away and it was still solid daylight - on forty meters.  Good receiver and the AlexLoop helps.

The CW filters come in three pre-programmed widths and one programmable width.  They are quite effective for very crowded band conditions, when all around you have their computers screaming '599' for some silly reason. 

I packeged rig in a Sigg, aluminium case made for mountaineers, contains 3.4 Amp/Hour NiMH battery, a mini-paddle bolted to the inside of the top lid, ear buds and etc. I use a small, multi-pocketed bag to hold it , additional batteries and an "AA" x 10 holder for emergency power, a 10 Watt folding PowerFilm panel, my rhinestone yo-yo and autographed picture of Perry Como.  ;-)

In short, fine rig, a little less than the venerable FT-817, no VHF/UHF but far better filtering for HF.  I prefer to carry an HT and an HF rig so that I can monitor operating in camp on the HT while active on HF: not limited to one or the other.

I like it.  It's right at the edge of what I would spend for it though, being so close to the price buying another FT-817. I think pushing the price downward toward $500 would make them sell like hotcakes.

Additional features: as it arrived, it was a ham band ONLY rig - no SLWing outside of the ham bands.  However, band edges are programmable in menu driven software ( a little tricky the first time) so I spread out each band so that I could listen to shortwave, utilities and etc. EZ-PZ


de RadioRay  ..._  ._

Have a look. I've been watching this and have ALREADY pledged my TINY amount of money where my mouth is.  Watch the video and see whether this makes you wake at night to run to the mail box, hoping it's there!

>RadioRay ..._  ._
Technical Corner / RF Noise Source Found
November 08, 2014, 05:09:18 pm
I've had a source of local noise, but never really tried to track it. However, today I put-up a 'quickie' vee-beam pointed at a friend of mine and when I would switch form the Delta loop to the vee-beam, the noise jumped from S2 to S8!  Several things crossed my mind (Martinis, dancing, becoming Emperor of Earth, a new KX3!!!) however, there was something else - a major difference in the two antennas: location.

1.  The vee-beam terminated near power lines.

2.  The vee-beam passed over the house.

3.  The Delta loop is away from the house and the powerlines.

I decided that it would be better to test the house first.  Seems that the local power company thinks poorly of people who drop the power grid to check for radio frequency interference - at least that's my impression.  So, I tuned to an open spot on a noisy band and began turning breakers off.  When I reached the living room breaker, the RF noise went from S8 to S-unreadable on the meter.  Aaaaah!  Long story short, the family computer system is served by that breaker.  I powered back ON and the noise came back.  It turned out to be the Linksys wifi box, making all that noise!

Now, my RF noise level is basically zero, because it's not merely the remoteness of the old antenna system from the house helping, but the source is DEAD, DEAD, DEAD!

Reminds me of a merry tune from 'How The Wizard of Oz SHOULD Have Ended':


de RadioRay ..._  ._
Here's a YouTube video of a voice contact from USA to South Africa. They eventually drop the power to one Watt. Evidently, the US station has a 200 meter long vee-beam (wire beam) antenna, but still, this is impressive! In Morse it would have been quite 'do-able, because of the virtual 13dB+ system gain of CW over HF radio.

On the other hand, this is an attempt at a 15 mW contact using a speaker cone to generate the electricity to run a small transmitter by ... er, ... well yelling Morse code into a bean can.  You just have to see this.

My ex-wife could probably generate a kiloWatt this way, she could yell so loud and long...

73 de RadioRay ..._   ._
Morse Code / Don't Ask / Don't Tell
November 03, 2014, 11:06:08 pm
. . . or 'Why QRPers Should Remain in The Closet.'

-This Is Based on Using Morse Code (aka: CW) Because of It's Power Efficiency. -

There is a mistaken belief among many ham radio operators that power is everything, a tower will help a little' but you MUST have a lot of power, otherwise the other fellow 'is doing all the work'. How much power?  the Voice of America would sneer at 'only 1.5 KW' ; the maximum power allowed for ham radio operators in the United States.  Many foreign ham radio operator's have power limits based on modern equipment, not spark transmitters and and coherers... (look those bits of radio history up) with maximum legal limits of 400 Watts and even a 10 Watts beginner's licence.  I wish that ALL hams had a 10 Watt limit, but that's not going to happen.  Here is what I've often heard happen on the air when the other fellow finds-out that I am running QRP.

1.   We exchange the formatted pleasantries of QTH, RST, QTH and name. I receive a 569 or more from a fellow and give him a report of say 579 or even 589, if that is what his signal is.  He is tells ma all about his powerful rig and usually not much about his antenna.  We can talk for a long time, but when I get around to running QRP, suddenly it's all fading and etc. 

2.  As above, but I never mention the rig or power and the conversation continues normally.

3.  When I mention my rig and QRP, the other fellow is happily surprised and maybe asks more about my antenna and feedline, if he is really technically savvy.

4.  When I mention my rig and power, the other fellow(s) tell me that I am a liar, because they spent all this money on all this stuff so I MUST not be using low powered, relatively inexpensive equipment to talk with them, especially a simple homebrew rig. I had this happen when I was chatting with a fellow in Belize (SSB at 2 Watts) and a couple of gomers over 1,000 miles away from me were incensed, because they spent all this money on all this stuff' so they were screaming that there 'was no WAY that I was talking to him and' they' could not even hear him.

' If "ignorance is bliss", then why aren't there more happy people?

5.  Occasionally I mention the rig and power and the OTHER fellow let's on that he is also running QRP.  Never would have known, because they had a workable signal, then we both laugh.

I've tried explaining that propagation is first, antenna is second and power . . . down the hill from there, in importance.  Good filters and the knowledge to use them in important. I am horrified to find hams who spend a TON of money on rigs, yet, have no idea how to use their filters or make efficient antennas - then again, nobody ever showed them: multi-generational ignorance = expensive bliss.

Let me explain that I have no problem with people running 100 Watt rigs at 100 watts.  Turn it down to 75 or 50 and NOBODY is going to know the difference.  100 Watts reduced to 50 Watts is 1/2 S-unit on your S-meter; something your ear is not going to realize. However, it's heat for the finals/heatsink to dissipate, uses less juice.  Heck, I even homebrewed a fiddly, semi-stable HF amplifier for my QRP rig to drive.  It -allegedly- can run up to 140 Watts. Frankly, If I can't make it with 50, upping it to 140 is still under 1 S-unit on the other guy's receiver.

So, what think ye, fellow radio-lunatics? 

de RadioRay ..._  ._

I am selling my UParmored KX1.  This is the Elecraft KX1, but built for 'survivability' in the field or on the porch.  It's time for me to bild a new 'gadget' and besides, 'walking' further than the mailbox is not my strong point these days (Ha!). Here is the link:

Pics and a bit more are on the E-bay link and here:


de RadioRay ..._  ._
Most of you know that my Elecraft KX1 is quite different from the original design

I made a hardened/water proof version, it's case is a water tight Otterbox. It's worked well for many years and I've added upgrades & improved it's usability, but the KX1 Mk. 4  faceplate and inside of the lid was unpainted, but it is now.

The more than I turn on the radio, the more that I hate what ham radio has become.  An example:

W1AW the 'hams' ham station' publishes all kinds of very good SOUNDING ethical rules and gentleman's agreements about how to be a model ham, and promptly ignores it when it comes to their own operating practices.  Even regulations about operating ham radio for 'pecuniary interest' (i/e ham for money) had to be waived in special dispensation from the FCC (or ignored) to allow the ARRL (W1AW) to do what they do on the air and to pay their ham operator staff to transmit. Ho and,  QRM is OK for them, another special dispensation - like buying indulgences int eh middle ages- was granted by FCC so that they are not responsible for QRM, when they broadcast their bulletins.

Next is the collecting "599".  Evidently, when there is a contest, or a renamed contest called a 'special event station', some of which operate for a year on all bands most modes all at the same time with multiple operators, all using the same callsign, without control operator (special dispensation again), you can operate in bands where it's illegal -by INTERNATIONAL LAW- to contest. Oh, it's not a "contest"! We made-up a name of 'Special Event Station', though you DO get points, multipliers, special certificates and etc. as long as you pay for them after thinking that one of our many '599's was yours.

599!  599!  599!   599!   599!   599!

Gil and I were having a nice chat, when suddenly RTTY in the CW portion (but 'technically legal' RTTY)  stations all pounced, screaming '599' over and over.  No thought as to the fact that we were already on the frequency. 'Nobody owns the frequency' (except the ARRL) so if you're there, we're going to take, it is the rule in special events and other contests. All for '599'.

WE had to RADICALLY change frequency, mid-conversation because of the @$#^@&*(&*#^#&!

There is a common thread in my ravings: Most of these guys would likely not be able to do this if their store bought 'appliances' they use to commit radio-mayhem went PFFFFFFFT!  A single 3 nanosecond HEMP would make the bands safe for communications again!  Oh, I know there's that stigma about 90% fatalities in the nation to deal with

, but operating conditions for those of us who can survive, build, repair and operate a station on home made power, well, we'd have it KNOCKED!  We might be eating swill and very little of it, but MAN the bands would be clear!

The problem is that this is about the ONLY way that I can see 'good manners' returning to the ham bands, because from the top down, all that is encouraged is to buy every more stuff & collect '599' at any price.

-This sermon is available on CD for a $25USD offering-

73 de Ray
W7ASA ..._  ._

599 = BS
Technical Corner / Altoid Tin Receiver
October 05, 2014, 11:04:23 pm
Lately I have had the itch for building radios in little tins.  The Altoids is the QRP standard tin, so I thought that I'd begin there with the 20 meter RockMite: love it.  I found a cool little regenerative receiver for the 40 meter band.  Old men like me remember 'regen' receivers as being a little bit 'fiddly' but VERY good performers with minimal parts count.  Well, this is no different.  It's two transistors and a smattering of support parts, all operating from a 9 volt battery.  Naturally I put it into an Altoids tin. I've attached a picture.

Does it work?  Well, I copied Gil tonight using this receiver and he is over 800 miles away and was not strong in the big rig, so I was QUITE happy that he was quite readable using the little regen.  No filters in this little beastie, so your 'grey matter must do the filtering for you, like the old days.

The kit is called the 'Sawdust' receiver, available from:

They also have a QRP transceiver called the 'Splinter', 650 mWatt for 40 meters with freetuning receiver and VXO to pull the transmit crystal frequency a few KHz. It even comes with a key!  You have NO idea how tempted I am to build one.

73 de RadioRay ..._  ._

Morse Code / QRPp // HF Morse at LESS Than One Watt
September 17, 2014, 08:10:52 am
I was just reading through an older thread where Gil and I were in our regular (uh, semi-regular...) sked and for fun when I asked him to reduce power to one Watt, he instead turned it down all the way to his lowest setting of 100 milliWatts (1/10th of one Watt).  We continued the conversation.  Weak - yes, but quite copyable in Morse code at 100 milliWatts, or WAS it?  I was JUST re-reading that posting when my Ethiopian Harrar espresso charged engineer brain caught something I had glossed over before: Gil's feed line to the 1/2 wave wire antenna was (still is???) 50 feet of RG-178 coax.  A quick look at the spec sheet says that at that frequency, there is a loss of roughly 3dB in 50 feet of BRAND NEW RG-178 coax: reducing his power into the antenna tuning unit by HALF.  So, in actuality, he was radiating at BEST 50 milliWatts.  Yes, 1/20th of a Watt for well over 800 miles of communication. 

A legal CB radio can emit 100 times more power (5 Watts) than Gil was that day ( 50 milliWatts erp).

THAT - is something to think about. A quiet location, wire antenna, low noise receiver with good filters are all things which make this possible. We are using home made kit radios - at best.  5 Watts CW into a good antenna is usually more than enough to communicate reliably, unless your receiving station is in a noisy RF location - like many cities are.  Even then, there are phasing noise cancellation gadgets that go into your antenna line before the rig which make a HUGE difference!  This is not a filter for the noise, instead it nulls the noise before it reaches your receiver. I have one that I used when the landlord's daughter was dating some metro-sexual who rode an electric mini-motorcycle and put a battery charger at her house.  That cheap charger generated more electrical interference than an entire Chinese army electronic warfare battalion could muster. My noise cancellation device allowed me to carefully NULL most of the hash generated by his battery charger. Her parents should have eliminated him, but that is another story.

Some fun links:   Splinter 250 mW Transceiver  40 mW using Soviet mini-tubes!

More Code: It's a survival skill.

de RadioRay ..._  ._
Whilst roaming the web -during this CME- I came across this fellows website and it's really a delightful read about QRP, low power and the FUN that it brings to Ham Radio.  Don't expect these views to the force fed to us by the glossy magazine, operating on an advertising budget: they'd be out of business.

72 de RadioRay ..._  ._
I am certain that we've all seen the $14 QRP "FROG" transceivers on E-Bay.  The detailed description, evidently translated directly from Chinese to English, by someone who spoke neither language - probably a computer does not inspire confidence.

"3, the changing structure of isolating switch, eliminate launch receiving "kaka... "

Look, I've made it a lifetime practice to never put 'kaka' in my ears, but do we REALLY feel good about transceiver descriptions like this?    I'm still tempted to buy one, just to play with it, but I'll be certain to wear some sort of protection the first few times.

73 de RadioRay ..._ ._
General Discussion / Summits On The Air (SOTA)
September 08, 2014, 06:20:38 pm
I am certain that anyone who reads my postings and those of Gil, know that we despise contests, viewing all contests somewhere between head lice and almost as low as politicians on the "YUK!" scale.


However, that does not mean that I feel the same way about all 'organized activity' on the ham bands. Of all the activities out there in ham, nothing is more enjoyable to me than operating out in the woods, preferably from a mountain top; and I did this for decades.  Unfortunately, age and injuries prevent me from being out there now, but I spent a LOT of time operating tiny CW rigs - usually home made - in very remote locations. So, what brings this up? 

Less than an hour ago I was talking with a friend who I've been helping with their CW (Morse code on HF radio). After our contact, I was tuning around and heard all the usual stations booming in from Europe.  Nice, but mostly the silly (UR 599 TU) kind of "contacts" not conversations. Then a little weaker I hear CQ CQ CQ SOTA DE S57XX/p  (This is a station on a mountain top, operating portable calling.) As it turns out, it's a club station in Slovenia that specializes in SOTA operation.  I called and we chatted for a few minutes before he shut down for the night. Here wasa  fellow ham, operating a few Watts 'QRP' possibly with a home made radio, definitely from a mountain top, and having carried his equipment a specified distance or more.  THAT is the type of person I really enjoy talking with via radio.

Here is a link to the main SOTA site:

Check-out the posting about the 174 mW (yes - milli-Watt!) contacts.

and here is a blog of one fellow using a tiny RockMite transceiver:

Another organization which is for outdoor, backpack radio aficionados, is RaDAR. RaDAR not only has you pack the radio gear in to a remote site (though not focusing on mountain tops) the cool thing about them is that they REQUIRE the operator to pack-up and move the station a specified distance before they can set-up again!  This encourages TRULY "portable" and manpack radio operation.   

Here is a link to just one RaDAR site:

In a REAL communications emergency, these hams will be RIGHT at home.  Both SOTA and RaDAR eliminate all 'legal' cheating of pre-positioned antennas, generators, gas cans, refrigerators, trailers , parked behind the Piggly-Wiggly as practiced in the BIG name 'field' operations.

I may just serve as a ground station for these SOTA and RaDAR ops, when I find more about them.

73 de RadioRay ..._   ._
Technical Corner / Running 'Barefoot' ?
August 27, 2014, 10:09:08 pm
Well, so is THIS fellow and I think that he is standing his ground well. His feet are planted firmly on the ground. He's not a heel, but he is an arch ham radio operator...  OK - you get the picture.  Follow the link.

I like the Dutch - great sense of humor.

>RadioRay ..._  ._
Technical Corner / CW Audio Filter Kit
August 16, 2014, 12:06:19 am
I've been FINALLY begun having fun building low end, receivers and projects, after having a million-and-one other things on my plate.  Filtering on some of these receivers is either none-at-all, like the RockMite or very marginal.  So, I decided to build the NEScaf - switched capacitor audio filter kit from the New England QRP Club.  It's center frequency is normally peaked at 600hz, when the detent pot is centered, allowing a wide swing of center frequency, in case the other station does not know how to zero beat your signal, or you want to use the filter to slew through a pile of stations.  I also has a pot for bandwidth, which goes from unfiltered, down to a very narrow setting - which I cannot remember.  Please see the link below.

I fit it all into an Altoids tin (Wintergreen - blue) along with a 9 volt battery and tried it out on just about everything in the house.  In sort: it works!  This really works well.  You just run a patch cord (3.5 mm stereo on each end) from the audio out of your receiver to the filter and I like to use earbuds/phones when copying CW. The controls are bandwidth & center frequency (there is an internal trim pot to set audio gain/volume) and you use the receiver volume control/AF gain for your volume control as per normal. I found that using this set-up GREATLY improves a general coverage 'plastic' shortwave radio when listening to CW. You suddenly have a narrow CW filter, at least an audio filter. Even on my 2 transistor , regenerative 40m band receiver, this filter turned it into a MUCH more usable receiver. 

I would highly recommend this kit. Even for those rigs with some filtering, adding an audio filter after good IF filtering is usually quite helpful.

de RadioRay ..._  ._