09 septembrie 2014

Kantronics KAM Plus

I found on my junk box a Kantronics Kam Plus modem. It stayed there about 2 years untill I found (yes, in my other junkbox) a 25 to 9 pin COM adapter...
I connected to a terminal and nothing happened, just garbage on my screen so I search on internet  and came to this reset procedure:

1)  Open the case
2)  With modem power off, install Reset Jumper, K6 (near the largest IC), on the two posts.  ( no need to touch the battery).
3)  Using terminal program (WinPack or others) with baud rate set to 1200, power on the modem.
Modem should respond with :

....RAM OK

4) Power off the modem; return jumper K6 to one pin only.

5)  Power up the modem;  Watch for: 
PRESS (*) TO SET BAUD RATE*   (You must do this within 2 seconds).


You should now be in NEW USER mode. 

6)   Check your call sign by typing    MYCALL

8)  To change from NEWUSER mode to TERMINAL mode type    INTERFACE  TERMINAL

cmd:in terminal
in terminal

9)  To change from 1200 baud (because Airmail doesn't go that slow)  type in ABAUD  0 
cmd:abaud 0
abaud 0
ABAUD was 1200

Now, everything is ok , awaiting a proper radio and setup to test. Unfortunately, only CW and RTTY seems to be appropiate in these days since PACTOR, AMTOR and other modes like that ceased in favor of PSK.
Maybe this nice modem will find it's place as a APRS digipeater, who knows!

29 august 2014

My Dream "GO-BOX" for emergency communications. Or just for fun!

Well, I sibscribed recently to a FB group dedicated to emergency communications. Its a very nice group.
I do not believe in the FB because it's like the sand. You write something or find something but soon it's hard to find it again.
I like very much to have the possibility to go somewhere and try to make some QSO's. I am not a contester and I appreciate a nice chat with a fellow ham from here or anywhere. Therefore, I realise i really need a "GO-BOX" or a "GO-KIT" able to work all mode, all frequencies from HF to UHF.
Also the kit will be good for RVSU which is a network of hams involved in emergency communications for various NGO's here.
I will tell you my secret: My GO-BOX is on wheels!
It's a Nissan X-Trail "doped" with a lot of ham-stuff.

The main radio is a ICOM IC-7000 mounted in the trunk and the front panel remote. I finally made the permanent setup; the radio is under the trunk hood, bolted with the optional DC filter (OPC-639) and on the HF side I put a choke Balun  to reduce the common mode currents from the Codan antenna (or any  othe HF antenna) because the IC-7000 remote head is very sensitive to that issue.

The remote head is under the radio; i put it in place with the help of some industrial 3M velcro. In the left side is a small loudspeaker connected to the remote head. I use that velcro also for phones, portable radios etc...

The main attractions is the Codan 9350 auto-tuning antenna. Bulky but with outstanding performance, it's definetly a magnet for everyone's eyes, in march or in parking lot!

I wrote in other post about the custom mount for this antenna and about the connection with ICOM IC-7000 radio.

What I did lately was to put all the important wires in a protection harness.

 The main 12V DC is in harness, the RG58 and the command cable for the ATU antenna is in the harness also. Was a little tricky but the final result is amazing!

For VHF and UHF I use quarter wave antennas. I found that if I put a quarter wave on VHF, the same antenna is resonant also in UHF! A MMANA-GAL simulation showed that the UHF angles are somehow elevated but still a +2db at 0-15 deg. over the horizont so the antenna can be used well.

I preffer NMO (New Motorola Mount) for my mobile antennas. This is a special designed mount to accomodate proffessional antennas ant to whitstand to all the special conditions on a  mobile setup in full run. Do not ignore that! And also, keep in mind that a fixed mount is BETTER than any magnetic mount.

Here it is a NMO mount, VHF quarter wave antenna.

Now, for really serious things like emergency comms., I have a little toolbox with a 35 Ah SLA battery.
I was looking for a good battery eliminator but the price was too high and had to buy it from overseas! Hey, I think a little here and I know how to use a solder iron. Or solder station. Or something like that, you figure out...

So I made a very very simple "battery eliminator" or "separator", whatever, from a Schottky power diode. It was a bulky one, I don't know at what current is rated but did'nt burned at 14-16 Amps so must be better than that. In the little Hammond box I put a little 5 LED voltmeter to quick view the main battery status.
The later addition was a little digital voltmeter on a "Y" cable to view the voltage. Both of them are usefull.
The battery have two fuses, one for plus and one for minus.
Some hams think that if they put a single fuse, on the plus side, is enough!
Well, what if you make a shortcircuit between minus cable and the "plus" pole?

That toolbox cand accomodate the ICOM IC-7000 or anything else. In this setup made for Ciucas Trail Running (a 100 km mountain marathon) I have two Motorola mobile radios.

The lower is a GM360 VHF radio to talk to Salvamont (Mountain Rescue) teams and the upper is a DM3600 to use it with the Radioamateurs in the RVSU network (Radioamateurs for Emergency
In order to be able to use a single antenna, a diplexer is used. Is a Diamond 2000 with modified RF cables. The original ones was too bulky and used PL and N connectors.
A lot of hams use amateur equipments for frequencies above the 146 or 148 MHz. They tend to ignore that out of the regular amateur bands, the radios are very ineffective!
I measured a lot of radios and they seems to loose power after 150 MHz and become very insensitive over 155 MHz. That's how they are made...  So, in a emergency network I found a little stupid to use deaf and mute radios! Therefore, I will go with proffessional radios for that particular case and the choice is Motorola!

A completion to my HF setup is a AH4 ATU with a collection of wires. I use two lenghts, 8,5 m and 4 m as they are not half-wave, as reccomended by ICOM to use them with AH-4.
The trick here is that I made two lenght of control cable and RF cable (tied together) so I can use 5m or 10m from radio to AH4.
The AH4 can be used for tuning a horizontal antenna (dipole) or a vertical one (erected on a fishpole stick) using 2 equal wires or 4 counterpoises with a vertical radiator. That's why there are 5 cables at the same lenght...

Well, this is my GO-BOX!

4 wheels and radios!

For final, here it is with a strange VHF antenna on the rooftop!

24 iulie 2014

Simple oscilator for testing cristals

Yesterday I was a little bored and I was staring to a box full of quartz cristals. I was wondering what frequency was, especially a very old one with russian marks on it. I know from an elder that the number on the Russian cristal is not the frequency but some sort of code. Stupid, eh?
After I contemplate various possibilities of transistor oscillators, I came up with a simple, reliable and versatile TTL configuration, "a classic" to say it simple.
It's a 74LS00 oscillator in series configuration, the schematics is pretty self explanatory.
Now I cand measure with precision the exact frequency of my 38.9 MHz crystals which, by the way, are overtone! I will make nice filters  for 12.95 MHz on long winter days!
Without a quartz crystal, it self-oscillate around 50 MHz with a very nice sinus wave!

The signals are from pin 6 and pin 11:

Self oscillation>
With a crystal:

21 iulie 2014

My laboratory I

Some are curious about my lab tools.

Well, I do have some stuff collected in years.
The most important tools in a electronics laboratory are the scope and the signal generator.
My scope is a AGILENT DSO 1014A, a four channel 100 MHz 2GSa/s scope. I wish it was a analog one but they are very big and expensive. Why my wish? Because you can use it on some measurements where a digital scope is useless due to alias issues.
This scope is a nice one but, in reality, is made by RIGOL :-) Either way, it's a nice piece of equipment!

Agilent's DSO1000A Series oscilloscopes deliver the performance and features you'd expect in a big scope - and the portability and low price you require in a small one. They've redefined the economy scope by giving you more: more signal viewing, more capabilities and more productivity.

Description from Agilent webpage:
Capture long time periods with high resolution
All models provide provide up to 20 kpts per channel of convenient acquisition memory standard. The scope will maintain high-resolution acquisitions even at slower timebase settings so you can see the details on your signals.
See your signals more clearly
The DSO1000A Series incorporates a bright, crisp LCD color display. You can quickly view your signal from almost any angle. Unlike conventional scopes that always require menus to be on, the entire 5.7-inch diagonal screen is available for waveform display as needed.
True Zoom mode for signal details and context
Dual display and True Zoom shows your entire signal and zoomed in waveform details at the same time.
23 automatic measurements
All DSO1000 Series scopes come equipped with 23 automatic voltage, time and frequency measurements. Press the Measure key to bring up the three you use most often or display all single-channel measurements on the screen simultaneously.
Sequence mode for easier debug
Record up to 1000 occurrences of a trigger event and then play them back to easily spot glitches or other anomalies for further examination. Store the waveforms to internal or external memory (USB flash drive).
Digital filtering on waveforms
Apply a real-time digital filter of your choice to the source waveform to eliminate unwanted frequencies from your display. Digital filtering selections include low-pass, high-pass, bandpass and band-reject filters. Frequency limits are selectable between 250 Hz and the full bandwidth of your oscilloscope.
Advanced triggering
Triggering options for the DSO1000A Series include edge, pulse width, composite video, pattern and alternate channel trigger modes. These modes ensure that you can capture and view hard-to find signal conditions.
Make fast go/no-go decisions
Automatic pass/fail mask testing comes as a standard feature on all 1000 Series scopes. Acquire a "golden" waveform and define tolerance limits to create a test envelope. Incoming signals will be compared to the allowable range and quickly flagged as pass or fail. This is ideal for manufacturing or service where you need to make decisions quickly.
Waveform math and FFT
Standard math functions include addition, subtraction or multiplication of any two input channels and Fast Fourier Transform (FFT) with four user-selectable windows (Rectangle, Hanning, Hamming and Blackman).
Programming and Connectivity
For remote instrument control over USB, use Agilent's I/O library or National Instrument drivers in your application. The drivers are compatible with Agilent VEE Pro, National Instrument's LabView and LabWindows/CVI.
Built-in USB host and device ports and free IntuiLink software make documentation and PC connectivity easy. Store waveforms and setups to a USB flash drive, easily update scope firmware and print to any PictBridge compatible printer.

Here is a flash movie, pretty self explanatory:

Personal, I like the Zoom function, the Sequence and the Save/Recall.

The signal generator is a ZOPAN KZ1405 Function Generator  produced in the 80's by the Polish Institute and Scientific Equipment Manufacturing -Zopan.
It covers 0,01 Hz - 10 MHz in square, triangle and sinus waveform. It's a well built analogic signal generator and it works very nice. Only a little contact spray to the potentiometers...
Has sinusoidal, triangle and square wave forms, all of them with variable ratio (they call it "symmetry") and a very usefull offset setting!

Very, but very simple and reliable!
I will change the capacitors when I will have some time because I suspect that some distorsion at 0-10 MHz due to ageing.

Some guys thinks the KZ's are adequate for making music... Well, I don't!

Multifunction Generators Zopan type KZ 1046 0.0005 Hz-100 kHz from zopan records on Vimeo.

Thanks to a great Polish guy, I do have the schematics for my Function generator!  Niiiiiceeeeee!

18 iulie 2014

Digital Multimeters

I wrote about receiving the VC-1008, the new multimeter in my shack.
Well, I told you that I have a very old DMM, a Voltcraft VC98 with 3 and 1/2 digits.
I bought it from my first wage, back in 1995 and was around 200 USD at that time. A lot of money!
I never succeded in my trial to make him communicate with my PC via IR...
It has no autorange, the selector is a pain in the a&*^&* but it works! Yes, it works perfect and even has a bargraph wich is very nice. It's a backup DMM in my shack.

The other one is also a Voltcraft, a VC-960, top of the DMM in 2011 if I remember right... Have some issues with it but manage to make it back in service. At least at 90% (still have some problems with AC current measurements).

Here are some pictures:

The VC-98 near the VC-960:

Voltcraft VC-960:
 Voltcraft VC-98:

 Schematic diagram of the Voltcraft VC-960:

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