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Add undersigned radio

that is what we want to try and help you get rid of slightly okay so as the video title says a way to help basically add a filter circuit to your radio now what brought this on was was talking to mark the other day and he had mentioned I guess another shop what they're doing is is they're claiming they're doing a super tune you know to the radio and it's removing a lot of the noise out of the receiver honestly people there's only so much you can do by lining the radio what I mean by that is in a receiver circuit you know adjusting if' transformers in the receivers all you circuit there's only so much you can do to that before it starts to adversely affect the sensitivity of the radio you know you adjust for maximum sine head which is maximum audio with minimum noise but there's only so much you can do with it so if somebody's claiming that they're doing something phenomenal you know with their secret tuning they're just lying to you flat out and apparently what this shop is doing is they're actually adding what I'm gonna show you and it's something you can do yourself so save yourself lots of money you won't need anything but one capacitor and a soldering iron maybe a little piece of wire at the most but that's it nothing else no no fancy test equipment can be a cheap soldering irons you doesn't even need to be plug in the wall it could be a cordless soldering iron or even new one of these propane torch style soldering irons just something that gets hot and melt solder well I guess that would be the only other thing you would need would be a little bit of solder but what we want to do is is add a tune switch or a tune control to this radio a lot of radios have that radios like this don't so this is a unit in PC and what is this a 68 yeah this is a 68 XL it's when I pull it off the shelf but it works and what we want to try do is get rid of some of that hiss out of the out of the receive audio and what we're going to do that with is a capacitor now the value like I say a lot of radios have that factory installed there's a hot yet tune I low switch on the radios and all they do in those if you look at the schematic you can reverse engineer what they did they added a capacitor that's it they added a capacitor and a switch to make it selectable so when you do this modification you can install it permanently just solder the capacitor and where I'm going to tell you or if you have a switch let's say that you're not using so like in this radio if I was doing this to this radio for myself I'd probably disconnect the bright dim switch I never use bright I only ever used dim when there's a selectable brightness for radios dim the light bulbs and the displays last longer because they're not being driven at full voltage all the time so you know I could disconnect the bright dim switch hook up the illumination so it's a them all the time and it frees up that switch and then I could just install that switch in series with the capacitor and it would allow me to turn it on and off or it would be the same as let's say a different a cobra or any other radio that has a tune high-low switch what but what that's doing is it is in radios like that after the signal has come in through your antenna it's gone through the mixer circuits it's been down converted in frequency demodulated that signal then goes through so once it's been demodulated it's now an audio frequency it's no longer Snoodle RF left in there it's all audio that audio goes to your volume control and then comes out the wiper and goes to the audio amplifier circuit which then increases that signal level and then it sends it to the speaker it's just that simple Bobby it's more complicated than that but in a nutshell that's what happens signal gets down converted gets demodulated goes to the volume control because at that point it's audio and then the volume control sets the level that's going to the audio amplifier circuit which controls of all coming out of your speaker we want to add a capacitor right there you don't need to cut any wires you don't need to remove any parts out of your radio you're going to install this capacitor from the wiper of the volume control to the DC board ground that's it just that simple so it could be anywhere in here ideally you want to keep your lead length as short as possible but you know worst case scenario you can run a wire back to the negative terminal on your check yeah anywhere that's DC ground potential is what you want to attach one side of that capacitor to so you know all of these I if transformer cans in here they're all soldered to the DC board ground the transformer the outside strap Lynette it's soldered to the DC board ground when you look at the bottom of a radio you'll see big chunks of copper trace that just snake all over the radio that's the DC board ground potential so depending on what radio you're working on you may have different styles of controls you if it's a fairly modern radio it may have a tiny little guy like this not very big and it may even be attached to a circuit board you know a little small circuit board or a big circuit board for that matter but what you're always going to be looking for is the center terminal so this one has three terminals the wiper is going to be the center terminal if you're working on an old antique this is a control I built up for a tram d2 at one so this is a dual control and I specifically wanted to show a dual control because this radio is a single honestly a lot of radios have a dual control especially if it's a mobile they'll have a volume squelch control this one uses a single control for the volume and on/off so I wanted to show one of those so you knew which section to get to so like I say this one is an on-off control so it has the trying to do this without ripping this thing is tight its new but has the center and has the other the outer or rear control okay the volume control is going to be you're usually going to be your center so you know like when this radio there is a center okay this would just doesn't happen to be volume and squelch that's used for other functions but the center one is the one you want to get to there's so there's two sets of contacts on this thing the center will try to get a picture down inside of it if you can see you can see right down in there you can see when I turn this Center shaft the rear control is the one that's being used when you turn the rear or the outer control if you look down in the front section here you can see the wiper arm swinging by okay so you want to always go to on a dual control you're going to want to go to the rear control but the same thing you're going for the center contact and what you're going to do is is install a capacitor there doesn't there's not really a lot of requirements on that other than it can't be an electrolytic capacitor so don't use something like this alone am electrolytic capacitor it could be a bipolar it could be a aluminum style capacitor it just can't be electrolytic it can't be polarized it needs to be a non polarized capacitor now on radios that have that installed from the factory a tone switch let's say or a high-cut so even your radios like that have a tune it's just nowadays most radios don't call it tune they caught hi-cut because that's what we're doing we're cutting out the high frequency out of this so that's that's a one thing to be very clear about if you're in the high fidelity stereo radio which just means noisy radio this is not the modification for you because we are going to limit your audio bandwidth and what we're doing that with is a capacitor so it can be ceramic it can be a pot you like one of these down here could be a ceramic style capacitor it could be a poly dip so you just grab a drawer pull those you know it could be something like one of these you people are familiar with a little green poly dipped color is not important they come as you can see in several different colors from this like brownish red color to blue I mean it's just the manufacturers coating that they put on there but be a poly style this will work on tube type radios the only difference between doing this on a solid-state and a tube type radio is if you do this to a tube type radio just be aware that there could be high voltage at the volume control and if there is high voltage there you're gonna want to use a high voltage capacitor so again grab the door for capacitors here you know in a tube type radio' you might want to be using something like one of these you know these are rated at 600 to 630 volts but we're in a radio like this you know pretty much lower back in the cabinet over there and a review like this new you can just buy and it's probably the best thing for you to do because I don't want to tell you a value of capacitance to stick in there and you're not happy with it what I would probably suggest is is good like eBay or Amazon and buy a very cheap capacitor kit we don't need super high quality caps here shiny and honestly most of the Chinese the caps coming out of China nowadays they're pretty darn close I've tested a lot of them and man they're actually not bad you know they're better than I think in a lot of cases they were using back in the days when these radios stuff like this was built so yeah you can pick up a cheap ceramic capacitor kit or like a green poly dip and that's probably the best thing to get they're probably gonna be a little bit cheaper it's good to like one little small assortment kips kits of poly style capacitors but like I say it's really not important main thing is is the value and like I say for something like this low voltage caps are fine for tube type you may want high voltage if there is high voltage present at the the volume control it's just something to be aware of with tube type but this would work for pretty much anything stereos car or any audio amplifiers anything this will work with pretty much all of that and what we're doing is and it's the same thing manufacturers did the radios ahead the tone switches you're adding a capacitor from the wiper which you'll have the audio coming once it's demodulated goes through like an array do you like this to the am detector diode eventually it'll find its way to one of these outside pins on this volume control and then will come back out from the wiper the center contact that will then go to the audio circuit so you're going to attach a capacitor whatever value you decide to use is going to be attached from the wiper don't remove anything any wires or anything that's attached to these leave it on there you're just adding a park so solder one pin to there the other side if it's going to be a permanent installation that's non selectable with a switch the other side of the capacitor just goes to ground that's it one part boom done and I will simulate that so what I have I have looked down in here I have this red clip going to the orange wire here which goes to the center or the wiper on the volume control one off switch okay take my mount up there back out and then actually let me zoom back in here a little bit and then just for convenience to attach my ground clip because I'm gonna be hooking it up and disconnecting it I've soldered a little loop of wire to this transformer can just to give me a convenient place to take this to add this in circuit because once I once I touch this to ground that's going to add the capacitor into value and what I'm doing to add capacitances I'm using a capacitor substitution box here okay one of these little guys and it just has a range of non polarized capacitors from point zero 1 to point 2 2 micro farad and it's just selectable by rotating the switch now from 0.0001 to about 0.01 you're not going to notice anything the frequencies that a capacitor and that small value it would be really high frequencies once you get to about 0.01 and higher you're gonna start to notice the sound the high frequencies are going to start to disappear so you know if we were looking at this on a spectrum analyzer let me grab a wrap a paper okay so if we were to look at this on a spectrum analyzer you'd have your audio so if you were putting through white noise into the speaker of this thing yeah that might be you know basically what we'd see there'd be our light clothes around let's say 300 Hertz because most great use the audio bandwidth usually going to be somewhere between 300 to 3000 Hertz as the audio bandwidth so you know that would be this hump right here if we were viewing on a spectrum analyzer by adding that capacitor in circuit we're going to start to cut off this high end here it's not going to affect the low end it's going to affect the high end and the higher the value is in capacitance the more the signal is going to start to it's going to start to filter out and all it's doing is is taking that that high frequency content and grounding it it's just sending that frequency to ground where the low frequency can still get passed so enough jibber-jabber let's hook it up and see what it does so we'll turn it on got a nice noisy Channel I made sure I've turned on some battery charges I even had the camera part plugged in so I've got lithium nickel metal hydride battery chargers plugged in here the cell phone I got a tablet plugged in so yeah I've got all kinds of noisy RF you know nerve racking it's his creators plugged in right now so we got a really good noisy receiver so I'll set this to punt or the only one so you'll see right there I'll hook this up and there's no difference and until I get to about 0.01 there's really no difference once I start to get up above that we're going to start to notice the high frequencies going to start to cut out but luckily the high frequency is where most of that noise is you can see by the time you get to 0.22 it's really narrated the audience frequency spectrum down and you can hear now if I just disconnect it it's like more than cut the audio level in half okay now most radios that have a to switch from the factory you're gonna find their value is usually gonna be between point zero three three and point zero four seven that's the average I would say for most radios that have a tone switch you can put it at whatever you want so if you want more filtering you won't really narrow it up that's why I say if you get it to pass it or assortment kit you can play with these values I probably wouldn't get too much above 0.068 two point one once you get much higher than that in a.m. it is really gonna start to affect the fidelity you want to get rid of the noise because you want to try to hear the people you're talking to you but at the same time you don't want to limit the audio bandwidth so much that yeah you can hear the person now but now they just they don't sound right because there's just no highs or actually you've gotten to the point where you've even taken the mid one you all you up I mean anything left is the base the really low frequencies so like I say most radios you'll see point 0 3 3 2 point 0 4 7 so you know if I've disconnected that's the difference you know adding a point 0 4 7 in circuit gets rid of that really kind of pitch sound without affecting the mids the mids too much like I say you could go to point zero six eight a little bit more pronounced if you go like I say point one would probably be my maximum limit definitely a huge difference there but that's it that's all you got to do people you know like I say no fancy test equipment needed no special tools nothing just a capacitor stick a capacitor wiper the volume control the DC board ground you've effectively add a low-pass filter an audio low-pass filter to your audio circuit and helps to cut out some of that noise like I said from one of my understanding is some people were doing that saying that they're yeah they're super tuning the radio and they're not super tuning the radio they're modifying the audio circuit by limiting the audio bandwidth now to me that's a good thing as is I personally but that's a person that's a very personal thing what you want your radio to sound like and like I say this is something you can play around with yourself find that happy happy medium which you're happy with another thing you could do if you really wanted to get crazy with this modification you could install a rotary switch like this you know take like maybe a four or five position rotary switch and you could hook up you know let's say a point zero three three point zero four seven point zero six eight a point one and a point 1 5 micro farad capacitors to that rotary switch and then if you depending what position you're in it would control how much you know audio filtering you're doing if you need to add a separate control somewhere your repurposed one you take out a rotary can give like volume or not a volume but maybe let's say of if it had had a I don't know this one yeah it's got RF game might gain you know if you had a if you never use the RF gain which a lot of people don't you could remove the RF gain control hardwired that permanently and an installed multi position rotary switch there's lots of different ways of doing it but I wanted to show the easiest way to do it just add a cap one cap it's all you need like I say if you get one of those cheap little Chinese cap kits you just want to make sure that if you get a capacitor assortment kit that it has probably somewhere between point zero to two to like point one you want to make sure it has the capacitors in that range so those are going to be the ones you're probably going to be using when you do this modification so I hope that helps so get out there and get to modifying people quiet up your radios