The Quest to Reduce QRM – DSP & New PC and more in progress !

  • bit of a longer post today so grab a cup of tea is recommend, else scroll through the page until you get to the bit you want to know about

Several weeks ago I was browsing the local 2nd hand radio shop where my TS690 came from, and amazingly they had the DSP-100.

Kenwood DSP-100 – finding chicken teeth is easier

The DSP-100 is one of the first ever Digital Signal Processors. Kenwood were pretty ahead of the game when they released it. You will see all the filters and features you see in this unit in most modern transceivers, but this is (I guess) about 20+ years old, and are hard to come by. I dont mind saying this unit, 2nd hand was £333 ,which is only £40 different of what I paid for the TS690S, but what it brings to the radio is RF filtered and processed. The promise of ‘hi-fi’ quality SSB, AM, CW and RTTY was too good to pass up. And it looks gorgeous too 🙂

When I first set it up with my TS-690s I connected in my xggcomms Kenwood interface I started running into issues. I honestly believe this is no fault of the xggcomms device, but moreso on how the RS232 signal from the DSP-100 unit is processed and fed into the transceiver. Its fair to say whilst I was overjoyed in having the DSP, alot of what i do requires a good CAT connection to constantly adjust the frequency (FT8 & WSPR), so I reverted back to the Xggcomms interface only and started investigating.

Upon searching, other people had experience similar, but not identical issues. The key to fix this was the IF-232C. This translates the serial input into signals at the correct levels for the DSP & the TS690s.

Up until now I have been using a laptop, which had become increasingly over burdened with USB dongles/hubs coming out of it, also getting the computer to be ‘RF Friendly’ and grounded proved a challenge. The only way i could see to easily and reliably RF was via the USB port, and this little lenovo laptop computer already had *alot* coming out of the USB ports.

With that I decided to get a dedicated full-size ham-radio PC. Nothing expensive or new, in fact I was looking for ‘older’ models with a native DB9 Serial interface so USB to Serial issues would no longer be a problem. This HP Elite 8200 met the specification needs for what I would be using the computer for and was a reasonable price/availablity. I could add all the audio inputs and outputs to the native connectors and also use the on-board serial (or so he thought…)

HP Elite ports – native Serial Port and audio on-board

Having migrated PC i went about installing first the apps I know, namely Fl Digi and FL Rig. I have been using these for sometime for WeFax and love getting the images in. The good thing about reducing the QRM, i can visually see it has been reduced, as I will show later.

I did run into some issues with communicating with the PC, the Serial Port settings had to be changed on the PC also, by now I had also discovered i had ordered the wrong cable from RS Electronics, but have a replacement on the way. I went back to using a USB to RS232C interface for now, which after some tweaking worked. I’m sure I’m not the only person who would still setup a IF-232C, so here are the settings I used between my PC and the RS232C.

Screenshot of Windows PC Running Windows 10 and USB Prolific based RS232 connector

Incase its hard to read on the screen, heres the tabulated form

Bits Per Second4800
Data Bits8
Stop Bits2
Flow ControlHardware
AdvancedLeave FIFO Buffers at max and on
Table of Settings for the RS232 Port on Windows for Kenwood TS690S and IF232C

In the FL Rig for the Serial port the settings are as follows (Select TS450S as the transceiver) :-

PTT via CATEnabled
Retries..Byte intvDefaults
Init (Click)Connected
FLRig Settings
Kenwood DSP-100 with the IF-232C

Now I dont mind saying that I’m still learning, so understanding what filter to use when is very much a case of ‘try it and see’, but i will show a comparison between before I started all the QRM clean up and the acculmation of what I have done so far *plus* the use of the DSP-100.

WeFAX – local QRM is quite clear with the ‘banding’ visible across the otherwise clear image

As you can see in the above image, there is alot of QRM in the picture, the ‘banding’ consistant across the image, in this case probably caused by the Ethernet over Power adaptors, is very clear.

Here is a scan today, same antenna, but will all the additonal work to reduce QRM and the DSP in Receive mode filtering.

Reduced QRM, what you do see is from a fan running because its hot today 🙂

When less electical items in the house are running, namely fans, washing machines and the like here is an example image. Again, this is the same antenna, same external line filters/chokes and the DSP and recent QRM work outcome.

The ice-chart from Hamburg

The ice-chart from Hamburg is the equivlant for me as the last row on the eye-test exam. The letters on it are incredbly small and the details/dots equally so. Whilst with a zoom there is some slight distortion (so more to be gained!) there is a total absence of the QRM which was so present in the first WeFax image shown.

I am adding a MFJ-1026 to the mix now (Thank you Nevada radios, you are doing a great job during the lockdown !) and I cannot thank Steve from Xggcomms enough for the assistance he has given me. I asked Steve for some help on how would I go about connecting both the xggcomms and mfj-1026 at the same time, as they need access to the T/R Control line present on the ACC-2 port. Sure enough Steve was good enough to reply on how to do this, by way of opening up the connector and adding a connection to pin 13 and ground (I used pin 12 for ground).

From Page 22 of the TS690S user manual

I had recently performed an inventory of all the wires/cables,etc I had, so it was easy to find the phono socket I required to connect the back of the MFJ-1026 phono socket to the ACC2 DIN plug.

I first tested the connectivity between socket and plug, to ensure it would work correcly before opening up the xggcomms. I am generally unhappy about opening working equipment in that I could break it and make it unoperational, but as Steve had already offered his support should anything go wrong, i bit the bullet and went for it. Needless to say, it wasnt an easy job for me who doesnt do this type of soldering reguarly.

I had already pre-tinned and checked the continuity between socket and wire on the phono socket, so was confident that as long as I was careful I would be able to add the necessary wires to the respective pins.

I dont mind saying that upon putting the shielding on and checking before plugging in that i found that the case (which should be grounded/seperate) ended up being ‘shorted’ and no resistance was shown on the voltmeter. Undeterred I undone the case and carefully applied a small piece of masking tape across the top pins ‘tucking’ between pins to give some isolation. I apologize i didnt take a picture of this. This had the required effect and that when the casing and flexible connector were restored, the isolation between pins had been restored.

Having completed the cable, the next step is to install an external auxiliary antenna for the MFJ-1028 to match against. I considered several ideas, as in just using a simple end-fed piece of wire, to a range of ‘small’ antennas from Russia that attracted QRM to be used in this way. In the end I decided to get another DX Commander. Whilst I wont totally multi-band this will all 6 elements (in particular 80m requires alot of space) I can setup the 2nd vertical ‘auxiliary’ about 2~3 meters from the ‘transmit’. With this I should be able to ‘phase out’ both any local QRM as well as distant QRM meaning I should not only be able to get out more cleanly, i should also be able to hear and filter those very feint remote signals that currently sit ‘below’ the noise table.

As ever, I will keep posting with my battle with QRM, which I think I am winning one week at a time.

Webcam – some lessons learned !

So having got my webcam up and running with streaming, i had to migrate the streaming server to another PC (in this case a macbook) and relocate the USB cable going into it.

I resumed my daily antenna observations with the inclusion of checking over the camera and re-routing the cabling from the camera so it would be ‘free’ from the mast allowing more length into the ‘shack’

Come the afternoon I’m now perplexed why i can TX and seem to get out well, but RX is non-existant, apart from 18m, which seems odd. I walk the path backwards of changes, of which there have been a couple in the shack with the QRM bonding and all, to try and work out why my reception is so bad.

As i work thru the devices directly connected to the transceiver, no change in reception. I then go out and check the mast, no problems there. I unplug all the connections between mast and and tuner. No change ! What on earth can it be !

At my whits end I relocate the macbook and suddenly see the usb cable from the mac to the camera, albeit on the 2m/70cm mast, it now does have a different ‘vector’ from mast head into the shack.. could this be the source of my problems.

Low and behold, unplugging the mac and the webcam suddenly the channels come alive again. I had created a USB transmit antenna blocking pretty much everything.

I set about removing the camera and cable from the 2m/70cm mast and tidying the cables I had previously disconnected. Full filtered resumed, minus the webcam 🙁

After all this I remembered the advice from the ARRL and Youtube videos “EVERY THING IS AN ANTENNA, EVEN IF YOU CALL IT SOMETHING ELSE”. Hence why my issue had occured, i saw it as a USB cable, but it was an antenna, and blocking my HF.

I probably can fix this, but I’m already battling QRM and I want to reduce issues, not add new ones, so for now the camera stays off, but I was glad of the experience and I could fix and understand the issues.

Posted in QRM

The Quest to reduce QRM – Bonding

The never ending quest to reduce QRM continued after following the ARRL Grounding and Bonding book and the excellent ‘clean up your shack video’ from RSGB i have been planning to try out what is discussed.

The excellent RSGB ‘clean up your shack’ video

For my ‘shack’ i used the following components, other things like voltmeters and screwdrivers I already had.

GTSE Twin Pack Aluminium Foil Adhesive Duct Tape14.99
Digitus Assmann DN – 19 Earth Equipotential Bonding19.99
Items for bonding

The objective here is to ‘bond’ all the radio equipment together so it has a common earth, therefore not creating a ‘earth loop’ via the earth pin. Also it gave me the opputnity to fix things down and generally tidy the ‘shack’ radio desk up, as I would have to remove everything from the table.

The first step was to apply the duct tape. I check first that it did conduct before sticking it down ! I got the idea to try tape as I didnt want to spend on metal plates and the ARRL book some temp setups use tin-foil and baking trays – so thought this was a good compromise.

The next step was to attach the ‘earth’ bar. I put it at a ‘safe’ location to the back of the table away from where human contact should not be possible and also to give better accessability to the various earth taps on each component. I measured it up and pre-sunk the holes to screw into to make fixing a little easier

I then set about attaching all the earth, or in this case bonding, wires to the bar and positoning my KPO distribution to a place on the table. This had previously been loose and somewhat annoying and potentially dangerous. I measured up the location, pre-sunk some holes and set about attaching.

With the grounding bar connected to the distribution board I set about adding the devices. I checked for voltage first and kept the wires coiled nicely onto the now metal surface.

Comfortable that the right voltage was making it to the distribution board and the position of the feed & choke to the transceiver was good i set about adding the other components to be bonded together.

So i have completed ‘bonding’ all the HF equipment together. I will add more metal tape to the small shelf the laptop sits on and source a USB bond, which I think for the rig will complete the RF bonding of all the devices. I’ll continue to work around the ‘shack’ with more tape and bus-bars to further reduce the RF loops which go through the common ‘mains’ ground, but i’m satisfied with the measurements on the rig for now.

25/5/20 – additon

I’ve since connected the virtual earth directly to the transceiver. This is what the guidelines say to do, and I’m not about to analyse the deltas between the bus-bar and the virtual ground. When I have more experience of measuring and using the Virtual Ground I’ll see if this can be changed, for now i’m following the instructions so the wire from the ‘bus bar’ to the ‘virtual ground’ are directly connected between Tranceiver and Virtual Ground.

Posted in QRM

Adding a webcam to the mast

Having had a webcam available to me for some time since I now use a mac which has an in-built camera, I thought I’d put it to good use.

linux desktop now acts as a fancy router, main desktop for me ia iMac Late 2013 model !

There are a number of really good mast-webcams on the Internet/Youtube, so thought I’d give it a try myself. The webcam is a cheap-er Logitech one as I know that some of these cameras can get very expensive (4K/remote control,etc). Im not 100% this from Argos is an identical one, but its a smilar price/looking and all powered via USB.As I’m not sure of the longevity of the camera given its outside, something on the cheaper end of the webcam market is in order !

there was alot of usb cable to go up, or not as the case maybe !

The mast is approximately 10 meters tall and has my 2m/70cm J-Pole on it. It is well rigged and secured with a heavy duty mast vertical and ground stakes which are very well driven into the ground. I do take it down when the weather is predicted to get quite bad, but i can still reach Poole and of course my DRM hot-spot for chatting on Talk Groups via the Internet.

mast with camera and J Pole – one element is wavign around but after checking all is good on 2m and 70cms

The first challenge is that a regular webcam comes with around a 1 meter cable attached to it. I needed a good quality cable that would introduce as little loss as possible. Here the RS USB 2.0 Active Repeater Cable comes into play. I actually ordered 3 of these and to start with did attach all 3 to make sure the cables are not too tight or pulling, but 1 does the job nicely, and I’m left with two very high quality usb repeating cables for other projects.

For software I used free streaming software provided Open Broadcast System, namely OBS Studio which is available here It was very easy to setup and integrates easily with you-tube.

well rigged mast ensures that it will stay up until i wan it to. The USB cable doesnt interfere or go near coax until the feeder.

I entered in the required Token for streaming from YouTube and sure enough the webcam was on air !

The mast cam – for as long as the camera lasts !

I was really thankful for WY7W for checking the camera out and also sharing his amazing webcam video as well – i have to admit i was just ever so slightly envious of his amazing QTH 🙂

Well I’m hoping the camera holds out, be interesting to see how long it last

— additional 25/5

I’ve since had to remove the webcam due to QRM from the USB Cable. When i find time/have reduce all the other QRM in the shack i’ll re-introduce the camera, for now it sadly has to stay off.

Streaming with DXCommander on 80m

Was browsing my youtube recommendations when I saw Calum was live streaming, tuned in and could hear everyone, which was really amazing to hear Calum and everyone else coming out the radio live.

Calum was ace in putting out some calls for M7’s – given the amount of people that call into his CQ’s, it was so nice that there was a gap for us on lower power (10W) to try and have a QSO.

I put in my call and Cal took his time, but i was just too quiet, see the video below.
A very faint M7ALU

Listening i can barely hear my voice, with M7 being just about audiable and i can recognize the gaps of how i would say ‘Alpha Lima Uniform’. Its a shame i couldnt get on the log book, but nethertheless provided a very exciting and good evening enjoying Calum and using the DX Commander as well.

Hopefully the restrictions on exams will soon be lifted and the extra wattage will help me get out that bit more. Fingers crossed !

Kanga DX Direct Conversion 40m Receiver Kit – Stage 3: VFO & VFO Buffering – Tuning and use of oscilloscope

So having got the lab somewhat tidy (pics and a full reveal will come soon !) i can continue working on my 40m Receiver Kit – having wound the toroid and secured it previously, the next step was to add the components and buffer around the tuning circuit.

I would like to point out (maybe again) that one thing that i think is very much missing from this kit is a schematic of the ‘blocks’ of the decoder. At this stage it would be very much helpful to understand what components and how the modules worked together, in particular when we get to the stage of the ‘decoder’.

Capactors, IC’s and variactor Diode !

I found getting most components on the ‘push-thru’ was easy enough, the only components which presented a ‘challenge were the NPO and Polystyrene capacitors. As you can see the round circles for C27,C28 and C30 are ’round’ enough when the capactiors are verticle.

Capacitor mounting

On the first attempt i tried the ‘test’ method of using a radio tuned to 7Mhz and got nothing at all. It also didnt help that I didnt know what i would be looking, or in this case listening for. I took a break and came back to it the next day.

visually looks fine, but actally a dry join on the trim.

Tracing my work I found that i had left a slight dry join on the trimmer. As i have now aquired an oscilliscope I thought it was the perfect use to find the frequency and adjust it.

We have a 7.5Mhz frequency!

I was so happy to even see a signal on the oscilliscope and also the read on the frequency was not so far out from the 7Mhz. I was lucky enough that the oscilliscope probes come with tuning screwdrivers which are the ‘safe’ type required to tune the trim. I set about tuning to 7Mhz !

Close to 7Mhz

On the scope i could the frequency to read between 6.90nnn and 7.000nn. I thought about trying to see if I could hear anything on my handheld standard (AM) and my transceiver which has more modes (including CW & PSK) as well as specific filters.

7Mhz = beeep

I was very happy to pick up a clear signal on 7Mhz. What was interesting also was that where i have the probe into the VFO / Decoder board, it had turned the ‘wire’ into a small resonant circuit – in fact I could turn my VFO into a theramin ! After 15 minutes of playing wooping noises I set about completing/and tidying the kit up.

I’m really glad that the receiver is going so well – its been all the work I thought it would be but its now very satisifying, esp as its gets more complex.

QRM & Power Line Adaptors

So last night (11/5 – 12/5) Turned into a bit of a QRM mission. Not exactly sure how, but found myself really getting trying to find the source of a specific hum, as I am gradually reducingt the amount of interference/QRM I am picking up. I started with taking my little AM radio (D-328) around the house buzzing very present. What I wanted to rule out was the utilitys nearby and the garage. Being 1AM and wandering around with a pocket radio should make for amusing footage on the overnight security video from the garage today 🙂 Anyhow, I could pick none up.

I returned home,sure enough the ‘buzz’ was back. So as it was quiet in the house (trust me, we are 24/7 shop here!) i started going thru the fuse box, its an older one, but still thankfully a trip/RCD (?) type box where I can easily flip the circuits. Sadly the circuits are not labelled, which I find quite unprofessional, apart from the ‘light’ fuse. I started flipping fuses and on the 5th one the buzzing on the radio stopped, as did all the mains power to my study and I think the front part of the house.

I set about unplugging everything in my study with the mains back on, hum still there. So I started to research/googling hum between 50 and 500Khz – it seemed so precise, I figured it must be some form of ‘man made’ interferance.

Here is a video of what it sounds like :-

So you can hear it all the way up from 50kHz to a very loud abrupt end at 500kHz. I set about googling as to what that could be, and sure enough found th GM4FVM page on ‘power line adaptors’. I’ve been very careful to remove and limit the use of ethernet in the house now, so suprised that this had caught me out. I immediatly removed the BT Ethernet over Power adaptors I had. This is the result

A longer video with manual AM tuning and a ‘sweep’ of USB

If you are patient enough to have watched the whole video, i congratulate you 🙂 But you can hear the big difference between what a power line adaptor can do to HF/RF in a shack, i.e. completely destroy all but the strongest signals.

This morning I tried out WSPR, the results on receive and transmit speak for themselves :-

wspr map is somewhat busier…

So now its time for work but I think i have taken another big step in reducing QRM in my shack

Next Steps – reduce this hum MORE and MORE

DX Commander – Adding Radials

The DX Commander comes with 100m of very good wire, which is enough for making the 4 element (40,30,20,17m) vertical and some for radials. Having already bought 50 meters of wire for 80m I was still down on the count for both radials and the ‘all band’ – having complete the ‘all-band’ construction it was now time to sort the radials !

With the orignial wire and radials I had around 28-30 radials, which whilst much better than only 1 and improvement on 15, is still slighty short for 80m and also more radials=higher Db out at other wave lengths.

So what is the science about radials ? The Calum has a good video to help, and the references are very good, so I’ll put that here first.
Radial videos from Calum

So basically adding radials helps (I did try to find a video of a person fallilng off a boat getting onto a pier, but was getting to distracted…) I took 50 meters of wire (the same type I had use on the verticals) and set about making into 3.5 meter lengths, which some great help from my son Paul which saved my back alot in terms of getting up and measuring and cutting !

With the cutting done, it was time to return indoors for strip, crimp and solder !

I then returned outdoors to install the addtional elements. I doubled up on one existing element, but had a pretty decent fan of 3.5m wire elements going on now.

I’d need to an exact recount (will do so later) but I think I now have enough radials to accomodate the 80m vertical.

With having added the radials it was time to test ! For this I use FT8 as it has a great map and includes a signal report when a QSO is complete.

Reaching Kuwait on 17m

I was now reaching Kuwait on 17M and even better was that I could see the call sign in my WSJTX screen – i had to give it a try ! And sure enough within a few minutes (this guy was was getting alot of QSO’s in) I had made contact !

Contact with 9K2OW in Kuwait – a staggering 2,888 miles on 10 Watts of power !

So i think i could continue to add more radials, but for now I’m happy with how the DX Commander is performing and the radials are performing their function. I will investigate more ‘science’ based ways of radial performance, but his helps for now !

DX Commander – all bands & fettling

So its been a bank holiday here in the UK and its allowed me to work on quite a few different things (including re-wiring the Mazda Bongo door looms). When I got the DX Commander it came with enough wire for 4 verticals and the radials to support it, but I purchased some more wire from Radio World, namely the Watson Radio Products EQ Equipment Wire which goes for 40 per meter. I used Radio World as I had other bits and bobs coming from them as well, and my word, they are so QUICK to deliver (UPS Everything !).

I checked from the list what additonal wires I would need to make up., in this case only the 10m and 12m. Having learned from trying to measure the wire indoors I now measure all my wire outside. I have 3 meter workmans metal tape which so far has done me brilliantly in getting accurate measurements.

Wire (Frequency M)Length to cut
wire to cut for 10m & 12m

Having cut the cable I could set about using my new crimping tool I had got from Amazon, the Vastar 2 in 1 Insulated Ratcheting Wire Terminals Crimper (AWG23-10,AWG23-7. The reviews and price (£26.99)really hooked me, given how much just the connectors cost from Halfords.

So the first part was to obviously lower the mast, and then remove the existing wires, Going from 4 to 6 requires adjustment as per DX Commanders docs (pg 2) here.

I also reprinted all new labels, removing the existing ones. One thing I didnt do orginally was to put labels on the bottom plate, so this time I would ! First I organized the cables so they was easy to pick up add, not having things on the floor and in a mess really adds to health and saftey when doing this kind of work.

wires in respective order of frequency (10,12,17,20,40,80 – the long green monster!)

With the mast lowered I followed the instructions and relocated the SO239 feed wire and the 80m connection

movement of feed wire and labelling up

What really helps is the DX Commander stickers. On my spreaders i do them so that they should be aligned when looking down the mast, this gives me a good point of reference.

To start with I just feed the 80m wire up to where it would be for 30m and taped it down. I then worked around the mast feeder positions adding labels as I worked in each new wire.

Now the DX Commander/Calum does say that the clips used on the paracord are hard to undo once set, as I found. Having to try and extract one, manage to break a clip, and I had no spares. So, i thought, well superglue it is then ! With using the YOCTOSUN Hands Free Magnifier, i was able to get it to glue pretty much back on. I was then with the existing cut paracorde and elastic cable to add the other elements which required some vertical tensile strength.

I continued to add all the elements and was happy with the tension and how tidy they are. I also took some time to put some tape around the clips where sometimes the wind will blow and wires get caught in the juberliee clips. As I’m not taking the mast down and collapsing, this wont effect me in the short-term.

With assistance from my son, we got the mast vertical and I could start adding the existing radials I have. I add the radials in a N/E/S/W layout starting from the feed point, and adding where i have capacity. I also done a ground-visual of the 2m/70cm with my iphone (10x max zoom) and could see it was in good shape up there after I had raised it on Friday.

Testing and Results

So the next step would be to test. For this i used the two main data modes I currently use, being FT8 and WSPR. I used WSJTX v2.1.2 and finding a ‘gap’ to press the ‘tune’ button. This would give me repeatable results. I am using the TS-690S internal SWR reading and a 2nd hand HF SWR Transceiver (YW-3) for the external readings.

BandSWR TransceiverSWR MeterNotes
20OFFSCALE2.5RX is very clear 5/9
160OFFSCALETo be expected
30OFFSCALE80m wire ?
151.63Does the VV-3 work at this frequency ?
FT8 Testings with new elements on 10+12m and resonant frequencies/others in WSJTx
BandSWR TransceiverSWR MeterNotes
1011.25 Watts is the min setting on the transmit

I am really impressed with the S.W.R. on all the bands, whilst 20M gave a high reading, i suspect that the curve on this band is quite specific. Reception is very strong, so the wire is doing its job in selecting the fequency nicely.

Whilst I wasnt expecting 160m and 30m to be available, for thorughness and future recording, added them (should of done 6m in hindsight). I was happy to see 15m and 12m resonating nicely with low S.W.Rs on of 1.6 and 2.1 respectively.

I will upload a gallery as there is so much evidiential data to show,so browse thru at your lesuire.

The ongoing quest to reduce QRM !


So I never knew just how much can be done to reduce QRM and where it comes from ! Having bought some ferrite rings and having mixed results, I found this excellent site from M0NWK who thanks to his equipment and setup can really demonstrate how the chokes work, heres the site which also includes a link to the video here

My build was slightly different, as I cant wire in a main tripper, I can wire in an extension in from an existing outlet, I was pleased to see that someone had already asked this question on M0NWK’s page.

I kept the same ferrites as M0NWK but a smaller box and bought a mains filter to which the ferrite-wound would attached.

Heres my part ilst, I use Amazon Prime alot because things arrive quickly and via decent couriers, if I wanted to get this done in less time I could of sourced cheaper, for example the 6 Way Mains Connector can be bought from Richer Sounds cheaper, but I dont know how quick they deliver or who they use.

PartSourced FromUnit Price
Roundcable snap-it core,300ohm 25mm dia
Stock no.: 4669164 (*2)
RS Electronics14.76
sourcingmap Dustproof IP65 Junction Box DIY Case Enclosure Gray 100mm x 100mm x 75mmAmazon6.89
White 3183Y 3 Core 2.5mm 25 Amp PVC Flexible Cable Cut To Length Flex (10 Meters)17.99
Masterplug Heavy Duty 13 Amp Rewireable Plug, 57.5 x 48 mm, Black4.99
Tacima 6 Way Mains Conditioner and Radio Frequency Interference Filter41.92
Permaplug by Masterplug Two Socket Trailing Socket, without Plug and Cable, 13 Amp, White4.04
GTSE 10 Pack of 12 Way 30-76 Amp Electrical Connector Block, 165mm Length, White Terminal Block Electrical Connector Strips 15.49
Heat Shinkalready had
Table of parts used in the construction of filtered mains feed

I started with stripping back some of the 3183Y Flex to bare out the live, netural and earth wires to wind around the ferrite. The heavy gauge of the wire made this quite a challenge, certianly being able to open the ferrite made a big different in creating a well fitting wire to the ferrite. I used cable ties to keep the ferrite and the wires stable.

The Terminal block comes in a massive pack, but its really good quality and will undoubtedly have many uses in the future, so worth having around. I attached these to the ferrite and wires, but not before attaching heatshrink to the wire going into the terminal. This not only looked good but kept the cable tidy.

I then set about measuring the thickness of the coax to make suitable sized holes into the box. I went in thru one side and so the mains feed and outward to the filter strip plug, nicely gapped so the terminal connectors in the box had a good seperation from them.

When drilling the holes I used a regular drill, but fettled the holes with a small round file to get the edges smooth and remove all the excess produced from the drilling.

The choke in its box – right side is the feed in, left side goes to the power strip with further mains filtering on.

Before plugging into expensive radio equipment i tested on a B&Q light to ensure it would turn on and off/and light. (The lid is back on at this point) As this was my first time using this I kept one hand in my trouser(probably short) pockets, but the lights came on and no problems. I then set about putting it into the mains outlet and to connect the additonal filter

Mains filter after the RF filter which supplies the transformer

You will see the parts list contains 2 ferrites, the 2nd one went onto the back of the radio power supply feed directly

Ferrite on the input voltage to the transceiver

As this is 12V DC and whilst can give a nasty poke, a box isnt necessary here.

I went back to the LW frequencies that had previously been plauged by a ‘buzz’ that had now completely gone ! I went onto 80m and 40m and weak stations were getting thru and loud stations were BOOMING.

Whilst this was a fair amount of work, I’m satisfied it has helped reduce my QRM further.