Thursday, June 13, 2019

Simple 10Ghz frequency counter #1

After previous post on the 10Ghz generator we need to measure it.

The following method is probably the cheapest you could find for 10 Ghz measure, still not dirty cheap but considering the price of a real counter on a much lower magnitude order.

This is nothing more than an LNB for satellite TV feeding a UHF frequency counter module.

Circuit:

You inject 12V onto the LNB, DC block it and feed the counter input.

The LNB:

The counter:

...mine is a VFD display module placed in a box with additional crystal testing circuit you have also LED versions (search for PLJ-8LED-H RF Signal Frequency Counter).

To calculate your signal input frequency just sum 9.75Ghz

Keep in mind that this will give you an approx frequency since on most of the LNB's the 9.75 Ghz LO is far from precise. The ones with PLL are a bit more stable.
Anyhow it will let you know if you are in the ball part.


The oscillator feeding the signal was the one from previous post placed in front of the LNB with a piece of wire as antenna:


Total cost will be around 10Eur for the counter plus 15Eur for the LNB and additional components, compare that even for a second hand HP or EIP... ok compare just the price...


Have fun




Monday, June 10, 2019

Simple 10Ghz oscillator with FVC99 hybrid VCO

I wanted to test 10Ghz band, more like a challenge than for any practical application, so started some experiments.

One of the first builds was an oscillator, it's a simple module out of the shelf with just a companion pot for tunning.

The module is an FVC99 hybrid VCO and more data available here:
It's major advantage is price, something less than 10Eur. Cheaper that any other sort of VCO (except probably the cheap motion detector modules that I will show in the future).

Mine is covering 9.5GHz to 10.326 Ghz


I am lucky to have a Ghz capable frequency counter, in a future post will show how to measure in some other ways (cheaper).

Without any care on the output connection it measured -15dBm to -4 on the full frequency range.

Schematic:
So nothing more than power to the module and a pot doing resitive divider connected to the tune terminal of the same module (VT). It's 5V on the picture but I used a 6V regulator.

Keep in mind that i mistakenly connect the 78X regulator on opposite direction.. in case you follow the wiring on the picture....still thinking how I manage to do that the first time...guess i'm getting old.

 ...frequency calibration is more in the "around here" mark than any precision device. Enough for playing around.

These electrical installation boxes/housings are perfect for this type of assembly. just add a piece of pcb.

Have a nice day!






Sunday, June 09, 2019

AC panel voltmeter convertion to DC

Well, this is the first post of 2019.




Since the start of the blog the idea was always to document some of my projects and also as a means that others can be motivated to build something.
This would e a win win situation, the more people building the more need for components so the more shops would keep open since lately the tendency is for hobby electronics to decline. Also I would keep information on my project that could be handy when I have to fix them since I'm not good on taking notes.

Said that, here's a small conversion of a 250V AC panel voltmeter to 25V DC.
The schematic is nothing more than a series diode (using one of the existing from the original PCB) with a resistor and a variable trimmer in series with moving coil meter. The original schematic (for AC) is seen on the background.
Calibration was just using a 9V battery and setting the trimer to read 9V, (90V AC on the original scale). Not critical here since I just wanted a means of checking if one of my DC power supplies was outputting the selected voltage.









Have a great one!



 

Sunday, December 16, 2018

12 Months, 12 projects and some other posts.

In the first post for this year (2018) I wrote:

"...Happy New Year!
I'll try this year to post more project's, (at least one for each month) and some more simple ones in the middle, that including the failed experiments (I do have them). ..."

I managed to reach the set goal with my previous post (the 200 W 30db attenuator), still, posted none about failed experiments (there were).... anyhow there's still some days left to the end of 2019....


The posts this Year, (in reverse date order), so far, were ("P" is for project):

 P - 200 W 20/30 dB attenuator with 100 Ohm / 30w resistors

  - Inside Trimble 65256 10 Mhz TCX Oscillator

  - Stand for the JBC T245 - AOYUE 2663B

P - Skylab SKM52 - C&Q 84 - GPS module

P - New AD8307 power meter

  - New RF frequency generator for the shack

  - Park Air Electronics Model 2100 DIP switch settings

P - Back to the future - Arduino DCF77 transmitter

P - Teensy 3.6 + Si5351 connection and code

P - Teensy 3.6 + 2.8" TFT LCD Display SPI Serial 240*320 ILI9341 connection and code

P - MIC5205 (LB30, KB30) Low noise regulator, increasing voltage output

P - ADS-B In-line amplifier experiments and bias T for 1 Ghz

  - Mains power meter and rig energy consumption.

P - Bench power supply ( part II ) 

P - JBC T245 / C245 Iron tip controller

  - Insulated, Stackable Banana Plug - BU‐31104 - 4mm

P - Mini paint booth

P - RTL-SDR Dongle interference shield/filter


... to be honest I have more projects done than the posted ones but have being lazy in publishing them.

Have a great weekend!



Saturday, December 15, 2018

200 W 20/30 dB attenuator with 100 Ohm / 30w resistors

Between buying a 200 W probe/head for the power meter, a pre-made 30dB attenuator or making this project I chose the last option, it will not have the same frequency range but it's a lot more fun and a little cheaper . This attenuator is a nice way of extending the range of my existing 2 W power head URY-Z2 until the 200W mark. I wanted 200 W because in the future I need to test the FT-102 capable of that value.

The end result for the impatient:




The main schematic for the 20dB part is bellow. I added a after a 10 dB attenuator on the output, that was made with smaller resistors since it just needs to handle part of the final 1.7W (see further down the power distribution in the attenuator).

Keep in mind that the previous schematic only handles around 80 W if using 30W resistors. Most of the power is burnt in the first shunt.
A simple test layout diagram:

 The attenuator is only composed of 100 Ohm resistors (cheaper than the 50 Ohm ones on the flea bay) with the two terminals isolated from ground, so it was nice exercise to calculate and attenuator under this limitation.

 In previous setup and at 50Mhz, the attenuation obtained:

Not bad since the calculated value it's not exactly 20 dB.

The power dissipation calculation:


(addendum: just realized the power on the first shunt is miscalculated, should be 100W on the 100Ohm resistor and a total of 66W on the series 100 ohm with the 2 parallel 100 ohm)
The X marks the resistors that will be under power at an input of 200 W so the 100 Ohm (on the input, left side of the first shunt) taking 80w (100W is the correct value, see addendum) is now composed of 4 resistors, capable now 120W dissipation in total.

..and are the 4 ones diagonally oriented on the left top.

For the ground plane I used copper plate with 0.6mm tick and it had to be partially soldered in the oven, the iron just could not make it, then on the final assembly the iron just had to do the final touch.





Final assembly inside view:
The end 10dB attenuator added is the "mesh" on the lower side of the picture/box.

For the final 10dB also a PI attenuator was chosen with these values: on the first and on the end shunt: 4 x 470 Ohm all in parallel with 1x 560 Ohm . For the series element: 3 x 220 Ohm all in parallel with 1x 2K7 Ohm resistor.


I include glued to the box a chart with the output value in function of the final attenuation, the measured one at 50Mhz (29.39 dB) and the calculated 30dB, this way if I don't set on the power meter the correction I just look at the table:






The VNA pass:

..still need to validate with more accurate power meter than the AD8307  from my homemade "VNA" and with a proper reference set, never the less looks OK for the type of construction involved.

So far I only tested with 100 W on the input, gets only mild warm for quick tests, for extended periods it might need to spread the resistors a little more and possibly include some thermal paste and better heat sink.

Approx cost of the project was as follows:

- N plugs: 3.20 €
- 30W Resistors (18) + 1/4W resistors : 12.00 €

- Box: 7.00 €
- Copper plate: 3.00 €
- Solder/paper/ink: 1.00 €

# Total #: 26.20 €


Have a great day!




















The schematic changed




Sunday, December 02, 2018

Inside Trimble 65256 10 Mhz TCX Oscillator

To be honest... nothing much; it's a Vectron OCXO MC2001X4-046W and some power control circuit.

 

In relation to the Vectron module, look's like this is the data-sheet:

https://www.vectron.com/products/ocxo/c4600.pdf


This is a 5V version of the Trimble 65256, most of the ones I've seen advertised are 12V versions, I am running it with 5V but found no diference in the marking's to the 12V versions...
Apparently mine is out of spec when I compared with a 10Khz derived from a GPS source... that could explain the low price they have now on the flea bay, served their life and got warned out/out of spec.

Bottom trace is the Trimble output divided by 1000 to give 10Khz



It's skipping forward around every 10s to the triggered top trace of the GPS 10Khz output. This is true for any of the control voltage range.

Have a nice week!


Saturday, October 27, 2018

Stand for the JBC T245 - AOYUE 2663B


In the beginning of this year I build a JBC tip controller for the T245 handle, it got a little cheaper than buying the original. Has been working nicely, in fact much better than any other iron i've used before (most of them, to be honest, was junk).
For the stand I've used an hold support but was not ideal because It was for a bigger sized iron.

Considered buying just the original stand part but was a it's a little bit pricier than expected, around 30 Eur just for the holder:

(model JBC 0012994)


Looking online I found another alternative and give it a go, was kind of risky since the sizing was not advertised, in any case, if would not fit the JBC then would fit some of my other iron's:


It's an AOYUE 2663B and it's advertised for the AOYUE brand soldering irons. The price was 12 Eur plus 5 Eur shipping, considering the parts included I don't find it a bad deal.

It turned out great and it's the perfect addition if you build your own JBC T245 controller and are on a budget.

Some pictures in use:

It also fit's nice on top of the heat controller box.
(solder is not included, all other parts yes) The brass sponge is even bigger that another one I had before.

It includes a tip holder which fit's the JBC ones. At the moment I only have one extra.
The mountings of the provided accessories are also ambidextrous which is good since I solder with my left hand.


The iron fits nice and it's easy to take and put back.


Whats "missing" now to build is the detector system for when the iron is in place in order to auto reduce temperature and extend tip live like on the original stations . That will probably be a next step.

Have a great day!