On This Page:
FT Meter   |   ALC Power Adjustment and Dummy Load for QRP op's   |   Field Strength Meter
Using a Dynamic Microphone with the Kenwood TS-590 home-brew DIY Cable Adapter
More About Microphones   |  Microphone Pre-amplifier Ideas   |   Icom HM-103 Microphone Mod's
Microphone Wiring  |  Morse Code Practice Oscillator  |  Shortened Top Band Antenna  |  Balun and UnUn Ideas
  (External Link): Antenna project - Dual band vhf / uhf dipole antenna

More pages:
DC Distribution Box with Reverse Voltage, Over Voltage and Transient Protection
   Speech Processor  |  Mic Preamps  |  Palstar PS-30
High Efficiency Extension Loudspeaker  |  Hands Free Mobile Microphone for FT-7900 etc
A PTT Switch for a communications headset by Ian MØIAT
An FT Meter by Ian MØIAT


DC Distribution Box with Reverse Voltage, Over Voltage and Transient Protection

“Anyone who has never made a mistake has never tried anything new.” - Albert Einstein


RADIO PROJECTS & KITS

One of the really fun aspects of amateur radio is making things for yourself and I like nothing better than making things, be they small circuits of kits or going outdoors with some antenna wire. 

Probably the best and most important DIY project for any amateur radio station is building an antenna of some kind. This is often a wire antenna for use on the HF bands such as an Inverted V, Inverted L, Dipole or Doublet Quad Loop or Windom etc. For the shorter wavelength VHF and UHF bands it's more practical to construct more complex antennas such as a single band Slim Jim or Yagis; I've had a go at a few such projects.

Other projects will be an electronic unit of some kind: For the Intermediate Level licence it is necessary to make several practical electrical and electronic circuits and also build a complete and useful device related to the subject of amateur radio. I chose to make a Morse Code Practice Oscillator; this project can be seen a little bit further down this page here.  I have also built a Field Strength Meter - "FSM" also shown further down this page here.

In January 2012 I set about making a microphone adapter cable to connect a dynamic 'stick' microphone and a separate PTT hand or foot switch to the Kenwood TS-590s transceiver. This, of course, led to looking at the transmitted audio quality and the subsequent filtering and DSP adjustments which has all been very useful and interesting. Read more here.


Due to being unable operate from March 2010 with all my equipment being packed away for a house move that had been constantly delayed and finally fell through, I began thinking about a few more ideas for homebrew (d.i.y.) projects. I have also put those ideas on this page:

I built a  a home-brew 'FT Meter' for the Yaesu FT-857D shown here and a QRP Dummy Load with power measurement and ALC adjustment for QRP operation of the FT-857D shown here.  Previous to those projects I also did a little microphone re-wiring - to be seen here.  I have also made some Baluns and Ununs and while I have not documented the whole projects I have noted down the ideas here. The other thing I have been doing is trying different types of antenna, my Compact Top Band Aerial can be seen here.



Using a Dynamic Microphone with the TS-590s and Microphone Preamplifier ideas:

I would like to be able to use a separate microphone on a boom or gooseneck, so I am bringing together some ideas for a dynamic mic' preamp and separate 'break-out' PTT switch here>

The components required for the small electronic projects were ordered from Bowood Electronics and JAB Electronic Components. ESR supplied a couple of different uni-directional electret microphone elements which are quite difficult to find elsewhere. I just need to find some time to start - sometime after we've moved house! The necessary electrical conduit and aluminium round bar or tubes for the antenna projects will probably be obtained from B&Q.



THE PROJECTS:


EXTENSION SPEAKER With Low Pass Noise Filter



Extension Speaker with Low Pass Noise Filter by MØMTJ  - Read more here >

Here's a nice simple little construction project that will make pleasant use of hour or two and produce a very useful communications speaker. My finished loudspeaker has a pleasant, clear sound and is very efficient, making the most of any transceiver's audio output power. The switchable filter is a nice bonus too.


I have found that most of the small communications extension speakers that I have used have a harsh, resonant and 'tinny' sound that does assist in making speech especially intelligible. Another problem is that many speakers are also quite inefficient - that is to say that they need a good degree of audio power to drive which can mean that the audio amplifier in the transceiver may be run towards its power limitations resulting in undesirable harmonic distortion or even worse, clipping distortion.

To overcome the harsh, tinny audio reproduction requires the use of a larger loudspeaker drive unit. To maximise the available audio output of the transceiver's audio amplifier requires the use of a highly efficient loudspeaker driver unit.

To find out more click here  >
 



FT METER  -  An Analog Meter for Yaesu FT-857D and FT-897D   -   The Homebrew FT-Meter:

FT-Meter - DIY Homebrew project by MØMTJ

Yaesu very thoughtfully added an external meter socket to the FT-857 and FT-897 which is excellent since I like analog S-Meters, so connecting a meter to these radios is child's play. There are no additional circuits required, merely a 100k preset potentiometer and a small microameter. A meter with a sensitivity of 100μA, 500μA or 1mA should be suitable, the final calibration being done with the small internal preset potentiometer, setting the meter for Full Scale Deflection using the calibration setting on the radio. 

Parts Required:
Panel Meter with a rating of 100μA, 500μA or 1mA measuring 60mm x 50mm or larger
A case of suitable size to house the chosen panel meter
Small rubber feet for case
Small rubber grommet to feed cable through rear of case
100 k Ohm preset potentiometer
3.5 mm jack plug Right Angled (I show a straight plug in the photographs, but a Right Angled plug is MUCH better!)
A length of thin screened cable - an offcut of RG174 would be fine. 



I looked at the Bowood Electronics website and found a very nice little 100μA ammeter measuring about 60mm wide by 50mm high, so I ordered one along with some other components that were in my basket for the QRP power reducer and power measurement project mentioned below.

The construction is very straightforward and should not need much explanation. The physical construction and the method by which the meter is fitted to the case will depend upon what type of meter and case is chosen and will be determined by individual ingenuity.

The electronic construction is very simple indeed comprising a 3.5mm jack plug soldered onto a short length of cable, inner conductor to the tip of the plug and the screen to the ring. The cable is then fed through the rubber grommet that has been fitted into a small hole drilled in the rear of the case.

Internally the screen of the cable is connected to the -ve terminal of the meter.  One of the outer legs of the preset potentiometer is soldered on to the +ve terminal of the meter while the other outer leg of the preset is joined to the centre 'wiper' terminal to which is soldered the inner conductor of the screened cable.

The menus of the FT-857 and FT-897 allow the radio to output indications of Signal Strength; Power; SWR; Modulation; Voltage and Discriminator etc.

Menu 60 -  I have set to 'SIG' to indicate signal strength in receive (RX) mode.

Menu 61 - I have set to 'PWR' to indicate power output in transmit (TX) mode.

The method for calibrating is described below.



FT Meter schematic circuit diagram drawn by Frank OK2FJ 




(I show a straight 3.5mm jack plug in the photographs, but a Right Angled plug is MUCH better!)


FT-Meter - DIY Homebrew project by MØMTJ
(I show a straight 3.5mm jack plug in the photographs, but a Right Angled plug is MUCH better!)

The physical construction of putting a small meter movement into a case should be very straightforward, but there was the small problem of replacing the 0 - 100μA scale supplied with the standard ammeter with a suitably calibrated and printed scale. Producing a new scale for the meter's dial with a professional appearance was more of a challenge for my graphics / image editing skills! 

I searched Google for some helpful images. LDG market two commercially manufactured meters for this job - the FT-Meter and the much larger FTL-Meter; these retail at about ￡46.00 GBP and ￡66.00 GBP respectively - my FT-Meter should cost about ￡10.00, but I digress! The photographs of these products illustrated the layout of the graphics, but nothing that was reproducible for this' home-brew' project.

I was beginning to think that I might have to draw something by hand - then I happened across the website of Frank OK2FJ. Frank has produced an excellent meter scale for his version of the Yaesu FT-Meter. Frank obviously had the same idea as me, to produce a home-brew FT-Meter for a fraction of the cost of a commercial unit, but Frank has greater image editing and graphics skills than mine. 

I saved Frank's image file and then made a few of my own simple modifications to the image file using a basic image editing program. The result is shown below and can be downloaded and saved, ready to be re-sized and printed to match the size of the particular meter being used: 


Above: The image graphic for the Yaesu FT-857 and FT-897 meter scale.
Save and print if required.

Printing The Scale: The scale can be printed on paper or thin card and possibly laminated, which is what I did. White paper or card might be the obvious choice, but cream, light green, yellow or light blue card might also make a good background colour.

Measure the horizontal width between the maximum and minimum point on the original (ammeter) scale. (Or with the original scale in the meter calibrate for Full Scale Deflection by entering menu 60 and set it to 'FS'. Then adjust the preset potentiometer so that the needle swings fully to the right and lines up with the maximum point on the scale and measure the distance between the two points.)

Remove the original scale and print out the new scale as a test print and measure the distance between the minimum and maximum points on the new FT Meter scale.

If it's too small, increase the size of the image on the page - using your word processor's functions - and print it again. If it's too big - make it smaller and try again until it's the correct size.

When printed, the image does need to be scaled very accurately to suit the size of the particular meter movement being used, otherwise the needle will not line up properly with the scale and the indication will be inaccurate. This can be done by trial and error until the correct size is found - a bit of a fiddly and a rather wasteful method. Use a good word processor application such as Microsoft Word or the free Open Office Writer to do this.

Here is an example document file to download and experiment with the size of the final printed image:  FT-Meter.doc


Alternatively a bit of simple math's can be used with an image editing program that allows accurate scaling:

My image editing program allows scaling of the print-out using a sliding scale that shows the total width of the image when it's printed and the dpi (dots per inch) output to the printer. Knowing the total image width isn't especially helpful since what is needed in this case is the dimension that is the distance between the left and right end markers of the S scale - the top curve. My simple image editor does not allow an accurate measurement of a portion of the image, so I did a test print, estimating that the resultant image would need to be 50 mm wide, the output in this case was 920 dpi. I then measured the width of the top curve on the test print, from end marker to end marker - it was 40mm. The scale of the original microammeter is 34mm wide, so the print had to be scaled down in size.

The magnitude of the size reduction can be found by dividing that measurement, 40mm, by the required measurement - in this case 34mm.

40mm  ÷  34mm  =  1.176 (the scaling factor)

The original test print produced an scale that, at 40mm, was too wide. It needed to be 34mm wide. The original image width of the test print was 50mm and therefore this needed to be divided by the scaling factor of 1.176

50mm ÷ 1.176  =  42.5mm

The calculation suggests that 42.5 mm is the width required for the whole image. The image was printed again at that width and the resulting print measured. It was found that the width across the top curve from end marker to end marker was, indeed, the required 34mm.

The other way of doing the scaling is to note the dpi output of the original test print, in this case 920 dpi, and multiply (not divide) that by the scaling factor. The original dpi figure is multiplied, rather than divided, because the dots per inch will increase as the original image size is shrunk. In this case the new, and correctly sized print, is 1082 dpi. Whichever method is used, the second print should produce a scale of the correct size.

Reference: http://www.radio-foto.net/radio/ftmeter2.png This is the original meter scale image that was produced by Frank OK2FJ, I altered this to produce the meter image that is shown above.


Calibration

1/  Enter menu 60 and set it to 'FS'.  Now adjust the preset potentiometer so that the needle swings fully to the right and lines up with the maximum point on the scale - i.e. +60dB on the Signal scale or 15 Volts on the voltage scale.

2/  When the 'FS' has been adjusted accurately, set menu 60 back to 'SIG' and move to step 3.

3/  Enter menu 61. As an initial check set this to VLT.  Exit the menus. Now press the PTT and transmit. The meter should now indicate the voltage - i.e. around 13.2 to 13.8 volts if running from a PSU. Once that is confirmed move to step 4.

4/  Enter menu 61 again and change the value back to SWR, PWR, MOD or ALC (i.e. whatever you want it to indicate when transmitting).

5/  Exit the menus.



For reference the Yaesu manual provides this information about Menus 60 and 61:

MENU MODE No•060 [MTR ARX SEL]
Function: Selects the analog meter display configuration while the transceiver is receiving. Available Values: SIG, CTR, VLT, N/A, FS, OFF. The default is SIG.
SIG: Indicates the incoming signal strength.
CTR: Discriminator center meter.
VLT: Indicates the battery voltage.
N/A: Not available at this time.
FS: Applies a calibration signal (1 mA for full scale) at the METER Jack on the transceiver
bottom, for adjustment of an external meter’s calibration. This lets you adjust
the external potentiometer in your metering system so that the external meter reading
is full scale.
OFF: Disables the meter

MENU MODE No•061 [MTR ATX SEL]
Function: Selects the analog meter display configuration while the transceiver is transmitting. Available Values: PWR, ALC, MOD, SWR, VLT, N/A, OFF. The default is PWR.
PWR: Indicates the relative transmit power.
ALC: Indicates the relative Automatic Level Control voltage.
MOD: Indicates the deviation level.
SWR: Indicates the Standing Wave Ratio (forward:reflected).
VLT: Indicates the battery voltage.
N/A: Not available at this time.
OFF: Disables the meter.


Above: The image graphic for a simple analog S Meter scale.
Save and print if required.

Don suggests: You mentioned using card stock for putting a new scale in a meter.  I had very good luck re-labeling a meter by creating an image "photograph size" and then having it printed on photo paper at my local camera shop with my other photos. 73, Don.

John, G0TEV, emailed with a helpful suggestion for those who want to produce a custom made meter scale: Meter Basic is free and will produce a basic linear scale. Meter is a paid for program that will allow  more complex designs such as dB, vu, VSWR and S-meter scales. 
Both programs are available here: http://www.tonnesoftware.com/index.html

Felix, EC2ALV, writes: Hi, perhaps this may be of interest to you I use GALVA 1.85 to draw all kinds of scales: variables, pots, meters, etc. for my projects. Just follow the examples and you will learn to use it fast. Kind regards, Felix EC2ALV

Stan, LT4TU, writes: Hello Mike, Please see my FT-meter scale. You can download the original Coreldraw file, designed by me: http://sites.google.com/site/lz4thankyou/projects/ft-meter There is no copyright, I am just happy to share and wanted to let you know.  I made my Ft-Meter in 2006. 73 and GL Stan, LZ4TU (ex LZ2STO).


FT-Meter by Wallace Moodie MM0AMV

Hi Mike, I really like your website, and thought I would just say thank you for all the information contained there. Just built your FT-Meter and chuffed to bits with it......pic attached. Flushed with success I may have a go at your Field Strength Meter next.
Kind regards to both of you. Wallace MM0AMV


FT-Meter by Wallace Moodie MM0AMV


An update, a few weeks later in December 2013:

Hello Mike, I trust you are well. I know it's sad, but I was laying in bed a few days ago thinking about the FT Meter. Mostly I use my FT897 out in the car working as /P, and I thought it would be handy to be able to keep an eye on the battery charge. I know I can set the original FT Meter to show voltage, but then you lose the signal/power facility. And so Version 2 of your meter was born.

I have also added 12 volt LED lighting for these dark winter days. All the best, Wallace MM0AMV





Version 2 - Dual FT-Meter by Wallace Moodie MM0AMV
December 2013



FT-Meter by Helmut Rupprechter DJ0FP

Hi Mike, As I  promised here some photos from my “ brand new” FT Meter. I found an 40μA ammeter, the case is made by myself because I could not find the right size. I wanted to make it small as possible so now it is 5x5 cm and 8cm long. It is black!!! Normally I hate black because everthing today is black, black cars and TV`s ,black transceivers and so on. But here it was better because the scale is very small and when the case is black the eyes will focus the white scale.
 
So thanks again for help and have a nice weekend. 73 DJ0FP Helmut Rupprechter.


FT-Meter by Helmut Rupprechter DJ0FP


FT-Meter by Helmut Rupprechter DJ0FP


FT-Meter by Billy McFarland 2MØCSP


FT Meter by Billy McFarland 2MØCSP




Hi Mike, 

I came across your website and tried your FT Meter Project.  It works!  I was very happy with it and wanted to share to you what I’ve done. I have incorporated it into my EMACS: Emcomm Modular Ammo Can System. See a photograph of Jesse's FT-Meter here.  Jesse Francis, KJ4KPV.  April 2013


More about the Emcomm_Modular_Ammo_Can_System  on this website: http://www.ar15.com
Jesse Francis, KJ4KPV.  April 2013


FT Meter by LU4ADC

Mike, Thanks to the info on your page I was able to build my FT-Meter the way I wanted. I have sent you some pictures. The dial scale is printed on 
270gsm paper which worked wonderfully.

Best wishes, LU4ADC


The large meter that LU4ADC used to construct the FT Meter
  

The finished FT-Meter by LU4ADC


An FT-Meter by Ian MØIAT


An FT-Meter by Ian M0IAT  -  click here to see more photographs





6 Watt QRP Dummy Load with Power Mea