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25
May
13

Circuit board toner transfer with Press-n-Peel

I received a 4 sheet order of Press-n-Peel to try out this weekend. I first discovered this product via one of Fran Blanche’s videos on her PCB process. At the same time, a post on the QRP-Tech Yahoo Group alerted us to a rock-bottom price at Amazon for the GBC BadgeMates badge laminator. For a mere $10.06 and a Prime membership, you get a laminator capable of being used in the Toner transfer process. Unfortunately, I had to revert to a clothes iron as the GBC unit was not quite hot enough to use for Press-n-Peel and the $29 toner I am using in my HP LaserJet 2200. Well, the toner works well with paper…

Below is a close-up of the 3rd test transfer. Very crisp all in all which should produce a fine etch result. I have many more experiments to run before I have a process, but so far the results are promising.

Fine details of transferred image

Fine details of transferred image

05
May
13

Why are different types of capacitors used in various circuits?

Electronic experimenters often wonder why specific types of non-polarized capacitors are specified or used in different circuit types and whether substituting one type for another will make any difference.

The short answer is yes; a specific type can be the most attractive choice in an application because its characteristics fit the type of circuit it’s being used in. Cost aside, there is no best overall type of capacitor to use in all applications.

The longer answer is that a particular type of capacitor may best suit the most important characteristic that circuit requires of that capacitor. For example, in LC oscillator circuits, frequency stability is typically an important attribute for the designer. For a similar situation in which the LC circuit is being used in a filter section, the Q factor may be the most important feature for the circuit designer.

Along with cost, the long-term stability, temperature range stability (coefficient), Q factor, voltage coefficient, and value tolerance attributes of each type of capacitor technology varies considerably. Consulting manufacturer data sheets can help you choose which type or types are the best fit for you application. Below are some common types and why one might choose them.

Ceramic (NPO) – Best temperature stability, tight tolerances

Silver Mica – High Q/ high voltage range stability

Polystyrene – High insulation/Low leakage

Polypropylene Film – low self inductance and high tolerance

Polycarbonate – High dielectric strength (breakdown voltage)

Mylar Film – Low cost

These are of course just some of the reasons you might choose one of the above types, but availability and cost are often very important qualities to consider in any choice you make.

10
Nov
12

The Softrock signal generator project, part 2

After receiving the BN-43-2402 binocular cores from Kits and Parts, I was able to add the T1 and T2 bifiler wound transformers.  I then chose to do the Band 3 inductors L10-L12 since they required the least effort to wind and install in order to test the end-to-end signal path. Lastly, I added a 51Ω 1/4 watt resistor between the junction of pins 7 and 9 on U9, and pin 9 on U6 – the only significant change to the stock design of the RX II in order for the divided output of the Si570 to flow into the ABPF section in reverse. In other words, having the signal flow out of the Ensemble RX II instead of flowing into it as a receiver.

The results were as good as I expected. From 16 MHz to 40 MHz, I measured a roughly -3db response out up to zero db and then back down again to -3db in the RMS output that peaked around 4.7 volts. The sine output appears clean on the scope, but I’d like to get it measured on a Spectrum Analyzer if I can hook up with another local Ham that has one. Lastly, I did the A and B calibrations using the CFGSR tool and was easily able to set the output to agree with my frequency counter to 5 digits after the decimal point, or 10 Hz resolution.

Next I’ll be building out the rest of the ABPF band sections to see the full response from 3 MHz up.

07
Nov
12

the softrock signal generator project, part 1

The Softrock Ensemble RX II is a good base for hacking it into a signal generator. Essentially if you build it out omitting the I/Q sampling and conversion circuit, the audio output, and flow the Si570 output into the Automatic Band Pass Filter sections, you end-up with a nice PC controlled (using CFGSR) signal generator.

In this post I’ll cover the basic starting points and progress into more detail in later posts.

Since I had nearly all of the parts to build a second RX II, I ordered a bare board and Si570 from Tony Parks, KB9YIG. I also ordered a few items from Digi-Key and Mouser that are particular to the way Tony put this design together. For example, the PCB mounted BNC, USB-B, and power connectors are each a little special in that the matching circuit board mates to specific part numbers. Of course if you simply purchase an RX II kit, you have everything you need.

The Si570 used in the Softrock kits is a grade-C part, which means it has an upper frequency limit of 280 MHz, or in the case of the CMOS output part used in the Softrocks, 160 MHz. Still, you easily get frequency coverage from 3.004 to 160 MHz if you follow the HF build instructions. Other grades of Si570 are supported in PE0FKO’s firmware, so it’s possible to go still higher; at least until the board layout begins to be a problem in the GHz range.

I also plan to use a Mini-Circuits ADE-1 to provide for modulation of the output. Once again, obviously if you just build-out an RXTX Ensemble, minus the final output, you can get most of the same functionality. However, the RX is nice because it has the ABPF switching.

One note on programming the ATTiny85, I have an Atmel STK500 development board and Atmel Studio 6.0. The ATTiny85’s come from the factory with default fuse bit settings that will need to be set to 0x5D high, and 0xE1 low bits in order for the chip to work correctly in a Softrock, therefore you must either reset the fuse bits before programming the EEPROM or use HVSP to program both the fuse bits and the EEPROM – an ISP alone is not enough.

01
Oct
12

ICOM IC-765

I had an opportunity to pick-up a well cared for IC-765 from the estate of a SK. This is my first commercial transceiver purchase and it made a lot of sense for me as a starter (100 W) HF rig. I have to say that the quad-conversion super het design is as good as the reviews I read and it is a simple rig that just works as others have written. Since I already had a 20 m End-fed Zepp, I got on 20 yesterday and immediately made and logged two contacts; 1 in Ontario and 1 in AZ.

This experience certainly put QRP into perspective for me as making similar contacts with 10 watts SSB would have been much more difficult or impossible during daylight hours. This certainly brought home the idea that success in QRP is about the conditions, location and the antenna you are using; and using CW or PSK31 modes. Challenges make a hobby lasting though.

The very next project is to get my planned antenna work done before it gets dark and cold here in MN.

29
Aug
12

ICOM IC-7100

This image was spotted after the 2012 JARL Ham Fair, 8/25-8/26. Will we see a US version? It’s odd that it uses a monochrome display like the IC-9100 when some would have liked to see the 9100 sporting a display more like the 7600 or 7000.

Obviously from the photo the IC-7100 appears to be a dedicated 2 piece unit rather than being 1 or 2 piece unit like the IC-7000 and others. I have read reports that the 7000 when used with the optional front panel separation cable has what seems like an ‘RF in the audio’ issue, which could be installation and user dependent, but I have to wonder if this is a new design made to be impervious to such problems. If that’s the case, it seems like a smart move.

Update: ICOM has posted info on the 7100 here.

28
Aug
12

SoftRock Ensemble II RX

My latest kit build, a SoftRock Ensemble II RX. The SMT components were soldered by utilizing 0.015″ solder and a Hakko 1mm tip. With a 1mm tip and my Hakko FX-888 set at 450 degrees C, the tiny tip provides just enough heat to solder right at the tip with the 0.015″ solder, thereby keeping excess heat to a minimum and the SMT components relatively cool.

A more formidable challenge was getting PowerSDR 2.3.5 working, but a post on the SoftRock40 Yahoo group provided the bottom-line details quite nicely. For those with a keen eye, yes the I and Q jumpers had to be switched for PowerSDR to get LSB and USB correct.