Cheap, simple, and effective urban dweller tv antenna

Most over the air television antennas (indoor) that you would buy at stores are usually full of gimmickry. They tend to say that they are the smallest and have the highest gain and usually include a pre amplifier of some kind. In my experience pre amplifiers usually cause more issues than they help. All of these antennas are compromise antennas, and usually none are very effective.

Some of them are just flat plastic boxes with a small coax cable that plugs into your television. Others have a telescoping antenna element, just one which would be a monopole that has no counter poise. All very poor.

Granted there will be no one simple antenna that will efficiently cover the broad range of frequencies that encompass the over the air television spectrum. Log periodic yagi type antennas are the exception but of course more complex. What is shown here is also a compromise antenna in that it is not tuned for any particular frequency. Nevertheless, it is very simple and fairly effective in an urban environment where television broadcast signals are fairly strong. If you don't live near broad cast stations this is not for you, you need height and gain.

I stumbled upon this idea, it is not my own. Simply, you take a metal coat hanger cut the hook off, shape it a bit so that the distance between the top and lower half are even. You then take a 300 ohm to 75 ohm transformer available at most local stores that carry television antennas or television accessories. The 300 ohm twin lead end gets connected to the cut portion of the antenna coat hanger. This assembly gets mounted to an insulator of some kind in my case I used a piece of scrap wood which also allows me to stand it up and let it lean against a wall near the television with the element horizontal. That makes for the complete antenna, very simple. All you have to do now is connect it to your TV with some 75 ohm coax.

This antenna is called a folded dipole which typically has a feed point impedance of around 300 ohms at its resonant frequency. At other frequencies this will vary but that impedance transformer helps to mitigate the possible impedance swings vs frequency at the antenna by its ratio of 4:1.

Brief practical non-scientific testing has shown this to be a fairly decent performer all local stations come in with around middle level signal strength as shown on the television used for testing. The television under test is located in a low area of the city. Signal strength typically in this area is usually poor with indoor antennas. 

This antenna is bi-directional in that you use it like a normal dipole and have it pointed in the direction of the station. In this case most broadcast stations are located in about the same direction. This antenna can also be expanded on later by adding a reflector this will create a nice gain directional antenna.

Image below, have fun!

Using 75 ohm coax with a 50 ohm vhf transceiver

RG6 is cheap, really cheap ( 🐦 ) compared to the lowest cost RG58. The losses according to data sheets are lower then the more expensive RG58 and can even compete with the very expensive RG8 stuff.

http://rfelektronik.se/manuals/Datasheets/Coaxial_Cable_Attenuation_Chart.pdf

For around 30 dollars from the local home improvement store you can get a 500 foot spool of RG6 where as RG58 can cost around 350 bucks for the same length online.

Using RG58 at VHF or greater frequencies is not recommended. The loss can be severe especially with longer runs. Being a very frugal guy I got to wondering, why isn't RG6 used instead? Why are transceivers designed with a 50ohm output? What happens if I just connect RG6 to my radio with a properly tuned antenna on the other end? How can I make this work?

Let's find out...

After some online research I found out that 50 ohm coax was chosen as a compromise between signal loss and power handling ability. You will notice that rg6 is used everywhere for cable, TV, satellite etc. These are all receivers or sometimes low power transmitters in the case of cable Internet. The 75 ohm coax is the impedance of cable with the lowest loss but suffers a bit on its power and voltage handling capability.

http://www.belden.com/blog/broadcastav/50-Ohms-The-Forgotten-Impedance.cfm

Typical RG6 has an operating voltage of about 300V. So I probably can't run a full 1.5KW through it. I have no interest in such high power anyway. This means I should be able to run RG6 on my transceivers so long as I don't use high power and everything (impedance) is matched fairly well.

I am already using RG6 on my HF radio the ts-520. This rig has an output matching network and easily accepts a 75 ohm load.

Modern rigs do not have this output matching luxury. Things also get a bit strange at VHF since wavelengths here are short. This brings us to transmission lines and how they behave as impedance transformers.

Consider this, I have a 2 meter ground plane antenna tuned for 146 Mhz and matched to 50 ohms at the feed point. If I connect RG6 75 ohm coax to this antenna and measure the swr at the radio it could be any thing from almost 1:1 to greater then 3:1 depending on antenna impedance. This is going to depend on the length of the coax. If my coax line is 1/2 wave length long it will mirror what is at the load and every thing will be happy. That is until you move frequency slightly in the 2 meter band. Everything is thrown off again. If your coax is 1/4 wave length long you have an impedance inverter and your swr will be very high. Any other lengths will give you impedances varying as I mentioned.

Of course any change in frequency especially at VHF/UHF changes the electrical length of your coax. At HF the wave lengths are large so this effect your may not see as the bands are only 300khz wide. You can tune the whole band without too much change in your coax electrical length. 

If this antenna was matched for 75 ohms and fed with RG6 you would suffer just the 1.5:1 mismatch. Some transceivers are okay with this and some aren't. Matching a ground plane antenna to 75 ohms is not easy. It will likely be less then that even if you turn it into a dipole shape or use a dipole. This is because a dipole in free space has a feed point impedance of around 73 ohms. Your antenna is unlikely to follow the free space model. Impedance normally goes down the closer to earth or any conductive objects it is. A ground plane antenna is just a dipole where the radials (or other leg of the dipole ) are used to match it's impedance to the feed line. The closer the radials to the main element the lower the impedance. Normal mag mount antennas are around 35 ohms due to the flat surface it capacitively couples to.

Alright, coax acts to transform impedance... We can use this I think. Enter the 1/12th wave transmission line transformer. For more information on this see:
https://www.cv.nrao.edu/~demerson/twelfth/twelfth.htm

Figuring out the length of 75 ohm and 50 ohm coax I needed for this was trivial. You have to take the cable's velocity factor into consideration but I think the tolerance does not have to be very tight as the bandwidth of this transformer is fairly wide.

Using a length of scrap 75 ohm coax and some scrap RG58 50 ohm coax I created what you see below. My lengths for 146 MHz target frequency was 3.57" for the 75ohm coax (VF: 82%) and 4.35" for the 50 ohm coax (VF: 66%). Basically the 75 ohm side of this transformer (BNC connector) is connected to the 50 ohm output of the radio and the 50 ohm side (F-Connector) of the transformer is connected to the 75 ohm feed line or load. This stabilizes the whole feed line network.

Testing with a home brew 75 ohm dummy load shows an SWR of near 1:1 across the 2 meter band.

AC9LF

Okay, so this will get me a 1.5 to 1 match with a ground plane antenna which is set at 50 ohms. Effectively this transformer stabilizes the SWR for the 2 meter band. Lets take this a step further. The J-Pole antenna. This interesting antenna is a half-wave end fed dipole made with copper pipe. As you move the feed point on a dipole from the center to approaching the end the feed point impedance increases. The J-Pole's lower J section is actually a matching transmission line stub. You match the antenna to your feed line by changing the feed point location on the J section. There are numerous calculators available such as this one: http://www.hamuniverse.com/jpole.html. I targeted a frequency of 146 MHz for mine and used mostly scrap 1/2" pipe for construction. This is what I have below:

AC9LF

Most RG6 shield is aluminum and easily breaks, Aluminum is also very difficult if not impossible to solder. for the feed point I used RG59 which is also 75 ohm coax with a bit more loss. The stuff I had was copper center, copper outer and PE insulation. I used stainless steel hose clamps to make for easy moving of the feed point location. Tuning er... matching was weird at first and I found out later through some experimentation that my coax air choke as shown was ineffective. The coax was still part of the radiating portion of the antenna.I got it matched 1:1 with 75 ohm feed line and the 1/12 wave transformer only to find out that when I moved the cable my SWR shot up above 3:1. This was because the connector pigtail was touching the antenna. That shouldn't happen. This was because of the ineffective ugly coax "BALUN". I attached a clamp on ferrite core right where the coax splits to the feed point and after moving the feed point around some more found the lowest SWR point. With the ferrite core attached it didn't matter if I touched the connector to the mast portion of the antenna or not. SWR/Impedance was now stable across the 2 meter band. I took my measurement bridge off and had a quick QSO with someone on a local 2 meter repeater with my HT. It used the 1/12 wave transformer to about 20 feet of RG6 connecting to the J-Pole pigtail. The J-pole was held up in a cat litter container.

Everything worked really well. Now I just have to mount this antenna outside which has the added benefit of the whole thing being able to get DC grounded. It is also a lot more rugged then my ground plane coat hanger hot glue antenna in the attic.

https://memegenerator.net/instance/66355681/all-the-things-yay-it-works

I have to admit it was a bit of work to avoid paying for premium coax cable. Nevertheless, this is where the fun and learning in amateur radio is! I have never before cut or soldered copper pipe. This has given me some experience in that now too.

I hope this little write up is helpful for anyone that stumbles across it.

73,
--
Nick, AC9LF

A new enclosure for my BITX40

I finally got around to stuffing my bitx 40 into a metal enclosure. Opportunity came in the form of a bad power supply in the garbage that was the right size. I repurposed its carcass.

Luckily the base material was aluminum so that was easy to drill, however the lid was steel. My drill bits suck on steel and are probably very dull now. I needed to drill holes in this cover for an internal speaker. These speaker holes took me almost 30 seconds a piece to get through the material. I would like to add more then I have but it is too time consuming with crappy bits.

The transceiver has everything but the battery and antenna tuner in it. The mic is on the face of it and the internal speaker on top. I couldn't use the audio jacks for external connections because the enclosure material was too thick to mount them. There is a hole for a future jack connection possibly for a speaker mic.

In the attached picture I have my homebrew L-match on top. This duo will soon be on the air. Switching the enclosure and extending some of the wiring took me all Sunday afternoon.

The new metal enclosure should help keep my vfo from shifting when something comes in close proximity to it. This was happening with the plastic enclosure. It is also more durable, I may even be able to take it on a trip...

Homebrew hand mic

Behold! My awesome hand mic and all its glory!

Made from the tin of Altoids, the electret element of eBay, the PTT of junk drawer and finally the TRRS jack of radio shack.

Used with standard male to male audio cable. This allows me to not yell directly at my bitx rig. Instead I can yell at a tin canister.

On buying used connectors

I purchased a used BNC to pl-259 adapter at a ham fest a while back. Had nothing but trouble with it.

First I thought that it was corroded, it is... On further examination while comparing it to a new fresh one I found that the inner female contact barrel inner diameter is bigger then it should be. This made intermittent contact with the BNC pin.

Serves me right for trying to save a buck. Buyer beware.

Bitx40 contact attempts

This weekend I have been trying to make contacts on 40 meters. Using the bit x 40. I am using an end fed wire with my homebrew L match circuit. I have not had any success yet making contacts.

On Saturday I used a tennis ball with some thin rope and threw it over a tree in the front yard. This took a few tries. After the tennis ball was over the tree I pulled up a thin enamel covered wire. I would say this wire is about 30 gauge. This wire is about 66 feet long which gets fed through the window. This wire is attached is attached to the L match circuit also has a counterpoise wire of approximately 3 1/2 feet.

I tuned up the bitx using a CW tone and my resistive bridge SWR meter. I had no problem getting a match close to one to one. I could hear stations very clearly most of them were very loud, however I am pretty sure a lot of the stations on the air this weekend were using amplifiers.

After trying numerous times to break into many different conversations two days in a row with no response I gave up for now.

😫

To be continued...

Finding Antenna Impedance (RF Noise Bridge)

RF Noise Bridge: Ported Over

Postby Mr. Nick » Mon May 09, 2016 12:42 pm

My next test equipment piece to build is called the Rf noise bridge. Known as the poor mans antenna analyzer. This fairly simple device can measure feed point impedance of antenna systems. It uses a wide-band noise generator which is just a zener diode that is ac coupled and amplified.

There are many circuits available. All fairly simple. I just chose one and layed out a PCB for it in diptrace. Made it fairly small for and OSHPark order. There is a transformer that has to get wound but it should be simple.

An MFJ comercial version: http://www.mfjenterprises.com/Product.php?productid=MFJ-202b

http://www.classicinternational.eu/_clientfiles/manuals/mfj202b.pdf

 

---

As of today (posting date):

 

I have built a little PCB based on a circuit I found online. It certainly puts out an incredible amount of RF noise well into VHF from what I can tell.

 

I am having some issues using only a potentiometer right now finding the null even with a 50 ohm dummy load on the antenna connection. I am using my HT as the receiver for this. I will experiment with adding the parallel capacitance to see if that helps.

 

The transformer is using the 2 hole ferrite core commonly available. I am using a 2.4V zener as the noise source.

 

I will probably be posting an updates when I have some time to mess around with it more. It is lower priority.

 

Here is the circuit I am using:

 

 

Kenwood TS-520 Repair

Kenwood TS-520 repair (COMPLETE, SUCCESS): Port over

Postby Mr. Nick » Mon Jul 27, 2015 3:03 pm

Starting this thread to track progress of the TS-520 radio repair.

520_Manual.pdf

User Manual

(4.73 MiB) Downloaded 1 time

TS-520_service.pdf

Service Manual

(5.32 MiB) Not downloaded yet

Edit: Added User manual and Service Manual. These include schematics for reference.

Last edited by Mr. Nick on Fri Oct 23, 2015 2:01 pm, edited 2 times in total.

Postby GoodBuddy1 » Mon Jul 27, 2015 3:07 pm

Do you have a good idea of what's wrong already?

Postby Mr. Nick » Mon Jul 27, 2015 3:10 pm

Well there is a transistor missing. I have to get a workable replacement then I have to trace signals through the unit to find any other issues. So... No...

Top

---

Postby Mr. Nick » Wed Aug 19, 2015 3:11 pm

Several Updates from different dates:

July 17, 2015:
I got a chance to give the radio a once over tonight. From the visual inspection I was able to find 2 issues so far. The first is that I am pretty sure the receiver didn't work because Q5 (3sk35) is missing from its socket on the rf board. The second was a ruptured electrolytic capacitor on the bottom next to a smaller transformer (16v 470uf). I already replaced the cap with a new 25v, 470uf I had on hand. The transistor however is some kind of dual gate FET device. I do not have any. I will have to hunt one down before I continue.

Once I replace Q5 I will work on getting the Rx portion functional. I have yet to apply power, wanted to check things out first.
--------------------------------------------------
August 1, 2015:
I was poking around in it last night and it looks like the vfo has nothing coming out. The oscilloscope shows a flat line when the vfo led is lit. I was working on pulling that section out until the wife got home. It has only 3 connections. What looks like 2 power wires and the main signal out. I don't know what the voltage from the red wire is supposed to be. Thinking about it now it may be where ever that is coming from as the red wire only has about 3 volts on it and I am pretty sure that should be higher.

I checked a few voltages and it looks like power is good at least from the main supply. It does look like someone else hand their hands in it from some cut and resoldered wires in various locations.

I will continue on it as I have time. I think I may need to wear a dust mask or something because some kind of dust or otherwise irritates my throat when working on it in close quarters. Not allergies just irritation that lasts a while. Weird.

-------------------------------------------------
August 2, 2015:
Spent a couple hours today on it. I was checking out all of the switches and dial potentiometers. Used contact cleaner on them and tried fixing some of the contacts that were not really touching very well.

The vfo requires 9 volts when I was seeing only 3. I traced it back to the fixed channel board. This has the 9 volt regulator circuit on it. I found the reference 6v zener diode (D3) was shorted so I replaced it with a 5.1v zener in series with a normal rectifier diode I had on hand. Measured at 6volts drop when I connected it to a constant current source. This isn't the only issue. The main pass transistor (Q4) had its base shorted internally to one of its other terminals. Can't remember which. It wasn't passing any current. I was thinking I may just replace the whole discrete regulator circuit with a 7809. I don't have any. I also don't have any suitable PNP transistors as a replacement.

I found a dual gate MOSFET that may work for Q5 on the rf board. Can't test it until the regulator is fixed.

Did check the AF board by feeding in a small signal to the DET pin and it did amplify and output to the speaker with varying levels of loudness based on the volume knob. So that's good at least.

May be a bit before I can find some replacement components to continue on. Don't know what happened to this rig.
---------------------------------------------
August 4, 2015:
Tonight:
Replaced the 9 volt regulator circuit with a 5 volt regulator 7805 and a 4 volt zener diode on its center pin to get 9 volts. The vfo seems to be pulling down the 14 volt supply now which is feeding the regulator and the regulator gets hot. I will dig into the vfo next. Some semi conductor may be shorted inside that can.

a little progress.
-----------------------------------------------
August 7, 2015:
Got the vfo out today and found that Q4 had its base internally shorted to its emitter. Replaced it with a 2n3904. Q1s gate seems to have been destroyed as well. Those dual gate FETs are hard to find. I may have to order something with similar specs. Most of the ones you can order online are tiny surface mount components.

I am suspecting the unit may have seen some kind of voltage surge on its main supply.
-----------------------------------------------
August 18, 2015:
I worked on the vfo last night and replaced the dual input jfet 3sk22 with a single input jfet I had in my bin. It was oscillating then but distorted. Turns out the second fet or buffer was bad. Internal leakage or something. Replaced that one too and the vfo came to life. I had previously replaced the output bjt which was shorted at the base to emitter. That means 3 out of 4 of the transistors in the vfo were bad. Since the new oscillator transistor didn't have a substrate bias I wasn't sure how that would effect it. It was varying in amplitude so I put a 1n914 diode across its gate and ground. This kept the amplitude constant. It matches the output the manual shows.

This is a little concerning. I have a bad feeling anything that was connected to the 9 volt regulator which itself failed may be bad. I speculate that the unit saw some kind of transient or someone plugged it into a 240 outlet. Something like that.

I am not sure what would cause the base to emitter and gate to drain junctions to become shorted.

I will likely be making a digikey order soon with jfets and dual gate MOSFETs. I made a PCB adapter for the MOSFETs because they are tiny surface mount devices and will require leads. 56cents surface mount vs 14 dollars for the appropriate thought hole component is the reason for the PCB. There really are only surface mount versions available.
----------------------------------------------

Postby Mr. Nick » Fri Aug 28, 2015 9:40 pm

August 28, 2015:
Tonight I fixed the carrier board. There was no output. Well there was but at 100mv peak. It is suppose to be closer to 1 volt. The Q2 BJT was shorted causing no amplification of the 3MHZish signal. Replaced and the output is now big and strong.

The panel meter has been pegged full right since i started. I fixed that by fixing the AGC. The issue for this was on the IF board. Q7 JFET's gate was damage and shorted to drain/source.

After fixing these last 2 items the radio speaker started to produce a static hiss. Still missing Q5 (the main rf input Amp) for now but I will have my adapter boards on Monday.

Seems I almost have the receiver portion going. lots of work and learning so far.

Postby Mr. Nick » Mon Oct 05, 2015 9:15 am

10/04/2015:
Haven't worked on the radio in around 3 weeks. I spend a little time on it Sunday night looking into why I had no S-Meter deflection when a strong RF signal was present from the RF generator. I can hear it on the speaker but the S-meter didn't budge. Found that the was a problem with Gate 2 of Q1 on the IF board. I swapped it out with the tiny PCB adapter I made and the SMD Dual gate mosfet I bought from Digikey. The S-meter is now deflecting with a signal input. However it is not deflecting as high as it should. This may have something to do with the RF front end of the unit. I will have to look into this. Once that is resolved I think the receiver should be functional and I will be able to string an antenna up for listening. Then I will look into transmitting. I will use the 50ohm wet dummy load I build this weekend for this purpose.

Attached are pictures of the Q1(IF board) transistor mount( was a tight area to work in ) as well as the Q5 (RF board) replacement which was originally missing when I got the unit. Just to show how the adapter looks.
Postby Mr. Nick » Tue Oct 06, 2015 8:11 pm

October 6, 2015

Good news well mostly, I caught a cold which is not so good. Any way on Monday I looked into the weak s meter deflection with the rf signal gen input. I found that Q9 (dual gate MOSFET) on the IF board had bad gates. The voltages were the same on all but one pin. Replaced it with another smd part with one of my little adapter boards. When I turned on the radio after replacing this the s meter went off the scale, which is good as the rf gen was still attached.

The cal signal was present and audible now as well. However the cal signal was present even when it shouldn't be with only vfo selected. Looked into this an hour ago suspected and was correct in that D7 and D8 wired to the vfo switch were shorted cause voltage to always be present on the cal unit. Replaced those with 1n4148s. Fixed that issue.

I put a short wire into the ant jack and I am hearing ssb and cw signals. Looking good. Next I will check out transmit. Just waiting for the caulk to dry on the dummy load I am making.

I may have to start working on an antenna setup soon.

Postby Mr. Nick » Thu Oct 08, 2015 3:17 pm

October 8, 2015

Just a quick update.

Last night I adjusted the VFO to be within specs of the 4.9-5.5Mhz and match the dial.

I was going to look into transmitting.

I connected the 50ohm dummy load to it and attempted to switch the unit to transmit on tune. There was no output and the IP meter was at 0 for plate current. Found out that driver tube was cracked. I will need to locate a 12BY7A. This may have been my fault when I was checking things out a couple months back. Hopefully everything else is okay.

I will likely install a stealth inverted V antenna for at least one band along the roof line of my house. I am hoping to get okay performance out of it even when held against wood and painted.

Postby Mr. Nick » Fri Oct 23, 2015 2:00 pm

I replaced the cracked tube and tested the transmitter using a homemade dummy load. Transmitting seems fine and I started to practice the tune up procedure. During this I found that the RF meter was not reading properly. It turned out the POT was bad for the adjustment on the side.

I verified that there is indeed a problem with the 28mhz and 28.5mhz bands. They are set 1mhz low. One is in the cb band, the other I don't know.

Everything else seems to be working now otherwise. I get over 100watts out on all bands based on rms voltage squared over resistance of 50 ohms.

I also built myself a microphone based on an electret mic and a small momentary switch. Got the 4 pin connector from radio shack.
Some pictures below.

Homemade 50 ohm Dummy load for testing transmit:

Most of the bad components that were replaced:

Rf volt pot was bad too, meter either pegged or was zero. The element was cracked:

New pot installed and working:

I may update this further with setting up the antenna system and first contacts. Otherwise, the radio is now working. I have no plans to change the crystals for the 28 and 28.5Mhz band. I will just not use them

Postby GoodBuddy1 » Fri Oct 23, 2015 9:53 pm

It's great to see you got it up and running. That looked like a daunting schematic to follow from what I saw.

Where there more bad parts then you expected?

Postby Mr. Nick » Sat Oct 24, 2015 9:39 am

Oh, yes. I was originally told there was only the band problem. But someone else had their hands o. The radio after that and ripped out one of the filters. A very expensive filter to sell on eBay. It goes for over 100 bucks by itself. In the process likely killed the rest of the radio. There was terrible soldering everywhere. Solderblobs and by the filter that was removed a trace was ripped off the PCB.

I believe it did work when. Mr mush had it. He handed it off to some electrician who just sat on it after ripping the part out. Mr. Mush asked if I could have it, which is how I got it. But of course the sucker was DOA.

Never met the other guy but ugh wtf man. I don't know if he knew he killed it or not. If he knew I should smack him for being an ass. If he didnt know I should smack him for being dumb and fat fingered.

I learned a lot in the process so it worked out anyway. The price was right aside from the cost of replacement components the thing was free.

Total I sunk 20 bucks into it was digikey parts. I still have a lot of spares so less then that if you only count what I used. $1.80 for the tiny PCBs. Maybe another 20 bucks for the mic connector, rf adapters, variable pot and grain of wheat replacement bulbs. I bought some spare tubes off eBay for 10bucks. So around 50 bucks.

Not terrible but not great. A new radio goes for about 700 dollars.

 

 

Pictures:

 

 

 

Homebrew Dip Meter

Dip Meter: Port over

Postby Mr. Nick » Tue Mar 29, 2016 8:38 am

I thought I would construct an old instrument called a Dip Meter. This is based on the QST article from the ARRL. The construction is a Nick Special with expensive materials such as used Tupperware and Hot glue.

I layed out a little PCB for the core of the project and had components laying around from previous things. A panel meter I was going to use for something else but didn't. A variable cap from a swap fest I got for like 2 bucks and a fancy frequency counter I purchased from amazon for 9.99 and free shipping from china.

Below you can see some pictures of it as well as the schematic and layout I did if you want to duplicate it.

 

I just used old RCA connectors to make the various coils for the frequencies of interest. They get plugged into the top and are used to magnetically couple to the circuit to be tested.

 

 

 

 

 

 

 

Video of it in action checking a homebrew dipole:

https://youtu.be/bTaOqbpnTtM

 

 

 

 

ESR Meter project

ESR Meter project: Port over

Postby Mr. Nick » Tue Feb 08, 2011 2:40 pm

I would like to start a group project. I think designing and building some ESR meters would be a good one. I know that being in manufacturing you guys probably don't need to measure ESR all that much if at all on those new components. However I think it would prove to be a very useful personal troubleshooting tool.

I have an LC analyzer here at work and it includes ESR measurements among many other things. I find bad capacitors all the time at work. They are usually visually damaged (bulged and leaking goo). There are however many a capacitor that is not visually bad and still measures out to be the correct value of capacitance. The only thing that is different that causes the circuit to fail or malfunction is the ESR value.

Check out link for some info on ESR.

http://www.repairfaq.org/sam/captest.htm#ctesr

There is a nifty kit as well.... I don't know if that would be the better route.
http://www.electronix.com/esr-low-ohms-meter-kit-with-stand-p-18234.html

Postby Mr. Nick » Wed Apr 29, 2015 11:10 am

 

Use this one: http://ludens.cl/Electron/esr/esr.html

I built one and it works pretty well.