Meters, testers, tools and tips
Freq-Mite by Small Wonder Labs
If you have actually no space on the front of your self-construction transceivers for a frequency display, this counter by Small Wonder Labs is the correct for you. On the front only the space for a tracer is required. The output of the frequency takes place thereby as CW word with 3 or 4 digits, whereby the signal is supplied easily to the AF signal. Due to its size of (3.2 cm x 4.5 cm) and the adjustable frequency offset each self-construction equipment thereby can actually be re-tooled. The maximal computable frequency is 32.767 MHz. These frequency counters be based on a PIC circuit. The counter was avaiable by Small Wonder Labs, which already closed.
Digital Frequency Display DFD1 by Almost All Digital Electronics (AADE)
For all those, which do not get along without a "correct" frequency display, I can recommend these display by AADE. Unfortunately, this manufacturer is out of business. The counter was also buyable from Funkamateur (Box 73). It's based on a PIC circuit and a LC display. The maximal measurable frequency amounts to 40MHz, whereby the adjustable frequency offset is adjustable in steps of 500 kHz to 16 MHz. Additionally still some symbols for the frequency (kHz, MHz, GHz) and the operating mode (USB, LSB, AM, FM, FAX, FSK, CW) are representable. The 8 cm x 3.6 cm large circuit board can operate with voltages between 8 and 20 V and uses a current of approximate 20 mA.
Counter without current
I had the problem to build somehow a counter or similar into a transceiver with VFO tuning over a 10-turn potentiometer however without frequency counters.
Old pictures in American magazines occurred to me again. With the devices illustrated the control and frequency display were combined. Well clearly! Thus with most of my devices the main tuning knob against a new tuning with scale were exchanged in each case. These new knob had a ratio from 1:3. As result a "counter without current" developed. With "calibration" uniquely a table with the relations is noted by counter reading and actual frequency. This table, which sticks with me on the top side of the transceivers, permits exactly an statement to the frequency up to 1 kHz. For all those, which are more interested in operation and fewer in a display of the frequency on the last cycles per second is exactly interested, for that is this version the best way. Different electonic companies and mail-order firms (e.g. Reichelt Elektronik and Conrad Electronic) offer fine tuning knobs with a ratio from 1:3 and in different size.
A number of reading meters avaible in the surplus stores. Most of these are FM tuning meters, but some are calibrated for use in CB transceivers. These meters are easy to take apart for substitution of a new meter scale and the other left over.
The circut can be use a small PC board or ugly construction.
The circut shown here is sensitive to make is suitable for power levels from 350 mW to 25 W. The diodes rectify the forward or reflected voltage (selected by switch) to provide a dc voltage for the meter. Trimmer capacitors form a voltage divider with the 300 pF capacitor. These trimmer are used to null the bridge with a 50 Ω load connected to TRX or ANT jack.
Reference: Doug DeMaw, W1FB, "Build this QRP omni box", QST 11/1987, 18
MFJ-259B by MFJ
The MFJ-259B SWR analyzer by MFJ is an easy to operate, versatile test instrument for analyzing nearly any 50 Ω RF system on frequencies between 1.8 and 170 MHz. In addition the MFJ-259B can be used as a signal source and as an accurate frequency counter. The MFJ-259B combines 4 basic circuits: a wide range oscillator, a frequency counter, a 50 Ω RF bridge and a microcontroller. This combination of circuits allows measurement of the SWR (referenced to 50 Ω), magnitude of the impedance, components of the impedance (resistance and reactance), of any load connected to the antenna connector. By connecting a signal to the BNC jack labeled frequency counter input it is possible to determine its frequency. The MFJ-259B provide a sine-wave signal of approximately UPP = 3 V to any load in series with a 50 Ω internal resistance. The MFJ-259B is also portable. It can be used with an external low voltage supply or with an internal battery pack.
If your device is out of order, so you can download technical documentations for MFJ-259 and MFJ-259B. The manual for the MFJ-259B is available ONLY on the MFJ webpage.
L/C Meter IIB by Almost All Digital Electronics (AADE)
A small, but very useful device, develops after short work from this kit. It is that L/C meters IIB by AADE. The L/C meter was buyable also from Funkamateur (Box 73). There is NOTHING comparable for this price on the market! Solder the fewer parts together and the kit will work. No alignment is necessary.
Ranges: 1 nH to 100 mH, 0.01 pF to 1 µF, automatic ranging.
Accuracy: typical 1%, self calibrating.
Display: 16 character LCD module with four digit resolution of the measured value, direct display in engineering units (i.e. Lx = 1.234 uHy), jumper option to display pF, nF, µF (i.e. 10 nF instead of 0,01 µF).
In the meantime I still made one modification at the L/C Meter, which saves the battery live.
WM-2 by Oak Hills Research (OHR)
The WM-2 by Oak Hills Research is a bi-directional power meter. It can measure the output power of the transmitter as well as the reflected power of the antenna resp. tuner down to 5 mW. The WM-2 works with each DC voltage between 9 and 13.8 V. Because the internal electronics has a very small power consumption, typically is about 1.2 mA, therefore the use is possible also over long time with the internal 9-V-Batterie.
Very pleasantly I feel the large, easily readable scale. With the WM-2 you can measure the power within 3 ranges (100 mW, 1 W, 10 W) with an accuracy of 5% of the final value. The WM-2 is suitable for measurements in the frequency range from 300 kHz to 54 MHz. Input and output are implemented with SO239 jacks.
Difficulties with many RF measuring instruments always prepares the calibration. With the WM-2 this is ingeniously solved. For the calibration no RF generator is necessary. It hands the anyway existing DC voltage for all 3 ranges!
Measuring with the WM-2 is simple: In the switch position FWD the forward power minus the the reflected power is always indicated. In the switch position REF only the reflected power is indicated. The switch position REF is thus suitable for adjusting tuners. When measurements always begins in the largest measuring range. Only if the displayed power is under a tenth of the maximum value, switch into the next lower range. Otherwise the pointer crashs at its mechanical terminator point.
In the meantime I still made a few modifications at the WM-2, which facilitates the work with it.
The power meter is also buyable from QRPproject.
RF/AF probe by QRPproject
Normaly you use to measure small RF voltages until 30 MHz a RF voltage meter. But you can use also a simple probe. Merely an easy digital multimeter is necessary. The probe is usable for measurements above USS = 25 mV, Ueff = 8,9 mV, P = 1,6 µV, P = -28 dBm.
You can convert the measuredly voltages fast with the standard diagrams into the existing voltage or power. Besides the probe is also usable for AF measurements. The probe ist buyable from QRPproject.
FA-NWT by Funkamateur (Box 73)
The FA-NWT from Funkamateur (Box 73) based on the NWT by Bernd Kernbaum, DK3WX. The distribution was discontinued so the device is now available only from second hand. It is a RF measuring instrument, which is nearly an all-rounder. The FA-NWT contains, it is true, "only" a sweeper, a sinus-wave generator and a power meter for frequencies always from 100 kHz to 160 MHz. But if you plug in some simple extensions, further measurement process can be mastered.
For example after plug in a reflection measuring head you can meassure the standing-wave ratio (SWR) at antennas or after plug in a 50-Ω-series resistance you can determining and graphically represent the impedances of units. The measuring capabilities are nearly unlimited.
All SMD parts of the FA-NWT, which are been located on the bottom side of the PCB, are already soldered in the kit. The suitable software comes from Andreas Lindenau, DL4JAL, and runs under Windows and Linux.
One would have to write nearly a book concerning the possible measurements with the FA-NWT an its extentions, if there were not already one: "HF-Messungen mit dem Netzwerktester" (in German) by Hans Nussbaum, DJ1UGA, and Rainer Müller, DM2CMB. These practice book was buyable from Funkamateur (Box 73).
FA-SAV by Funkamateur (Box 73)
FA-SAV is the name of a spectrum analyzer add-on for the FA-NWT, which was obtainable by Funkamateur (Box 73). The distribution was discontinued so the device is now available only from second hand. It is usable for spectral measurements in two frequency ranges (1 to 75 MHz and 135 to 148 MHz) as well as three bandwidths (300 Hz, 7 kHz, 30 kHz). All SMD parts of the FA-SAV, which are been located on the bottom side of the PCB, are already soldered in the kit.
The suitable software comes from Andreas Lindenau, DL4JAL, and runs under Windows and Linux.
SARK-110 by Melchor Varela, EA4FRB
The antenna analyzer SARK-110 is able to determine impedances in the frequency range of 0.1 to 230 MHz. The measured values are graphically displayed on an OLED display. It can measure resistive and reactances of series and parallel impedances, absolute magnitude and phase angle of impedances, standing wave ratio, return loss, insert loss, and equivalent series and parallel capacitances and inductances.
The analyzer was avaiable by the Funkkiste (www.funkkiste.de), but its closed at the end of September. It is, according to the SARK-110 webpage also avaiable by others.
Sometimes it is necessary to produce a wide-band noise. I use for it a noise generator, which was meant actually for an noise bridge. The construction on a universal circuit board with stripy circuit paths facilitates the construction. The interruptions in the conductive strips I realized with a 4 mm drill. I turned these with the hand, until the conductive strips in the appropriate place was interrupted. I replaced the original transistors by RF transistors from the junk box. A strong noise can be achieved by this small device over the whole short wave frequency-area. The specification of this device is available.
10 MHz frequency standard with RS-GGO10M-TG
Exact reference frequencies are necessary among other things for frequency counters. Otherwise you cannot trust the measured values. A GPS-guided 10 MHz frequency standard can be developed at minimum expenditure with the small module RS-GGO10M-TG. In order to achieve all in the data sheet specified characteristics, some general information should be considered.
NJ Islander and ICs
As a homebrewer you know certainly already once something over an ingenious tool of the NJ QRP Club. Exactly, it is the NJ Islander! Dov, AD0V, found this tools. TNX! With the help of a simple drill press it is now very fast possible to create a circuit boards without the otherwise usual method of etching.
The construction with normal components is easy to manage. If you use ICs it is more difficult. The Islander has a diameter of about 5 mm. Normaly you need a socket with long pins because the IC pins have a distance of 2.5 mm. It works however well, if one arranges the pads shifted. See the specification about it.
If you drill large holes in thin sheet metal, the result is unsatisfactory: The brinks are ragged and wavy. The process is essentially better done with a step drill and the result looks more pleasing.
Not only those who want to solder SMD components on a printed circuit board needs necessarily a reading aid. It is in addition to a dazzle-free illumination a prerequisite to obtain functioning solder joints without short circuiting. Compared with those in electronics stores offers available stand magnifiers it is possible to survey the solder joint from all perspectives. Additional your can see an adjacent component sharply without the relocating of the board. Some chains of retail shops are sell reading glasses that hold up to 3.5 diopters. You can use it as a good aid to soldering through-hole components, but for SMD components its magnification too low.
Therefore I acquired by opticians around the corner a special glasses by Eschenbach. Now RoNa produced a very similar form of glasses, which is available e.g. by Conrad Electronic (order no. 826578) for less than 12 €. The glasses possessing a magnification of V = 3.5, which should not be confused with the diopter values of spectacles. All items that are in the distance of the focal length f = 7 to 8 cm in front of the lens will be in focus (f = 25 cm / 3.5 = 7.1 cm). The 25 cm derived from the assumed distance from magnifying glasses and microscopes, in which one could see the object without optical aids still sharp. With a 3.5 diopter glasses it would be 1/3, 5 m = 28.5 cm. Also these glasses is with 30 grams very light, so it is comfortable to put on even over longer periods.
Sprat CD-ROM (first edition with issues 1-100)
The GQRP Club together with the German ham radio magazine Funkamateur have published in the year 2000 the reprints of the first 100 issues of the GQRP club magazine Sprat on a CD-ROM. It came together with a floppy disk with the call and address of the user on it. The second version of the CD-ROM with the issues 1-109 don't came with these floppy.
Sometime user ask, how to install the first edition of the CD-ROM with the issues 1-100 on a PC or laptop without a floppy drive. There are two ways. Maybe there are more than this, but I have tested only these both with success.
Sorry! Specification is under construction.
Coil winding - the easy way
Some homebrewer solder the maddest rigs but shy away from winding the necessary coils. I show you in a short tutorial, how to wind easy the small-sized coils manufactured by Neosid.
The showed procedure is also applicable for similarly coils by other manufacturers.
Stand for transceiver
Just little transceiver and accessories can be difficult to use, if it have no stand or fold-out feets and the controls are located on the front panel. It is better to tilted the transceiver. But the time is over to under-clamped just existing things for it. I will show you the building instructions for a cheap realizable stand. For it only a CD case is required.