Showing posts with label Other topics. Show all posts
Showing posts with label Other topics. Show all posts

Sunday, September 15, 2013

North Cork Radio Rally

I'm getting international in therms of radio rallies, after the Moscavide (PT ARVM) one, Leiria (PT ARLA) and Friedrichshafen (DE), now I went to Cork (IR NCRG).


 ...next is Dayton?
 
It was easy to find the spot since I had already explored a little bit of that area in town, arrived at 11H00, the starting time of the event, and everything was already set. Weather was the classical Irish for this time of the year; you guessed, rain in the morning and then some sun.... and then a little more rain, but was mild rain.
There were the usual sellers and the normal boxes full of odds and ends.

Got home this:


 I never learn....why did I asked the price of the rack airband receiver?...oh well, if it works I will probably leave it like this, if it doesn't I got a really nice quality box and a bunch of components.


I met Ed, EI2HEB who is one of the organizers of the event and we ha a little chat. From what I understood there was another foreign visitor from the Netherlands, so, that made this one a truly international event.

Unfortunately I did not took pictures because run out of memory on the phone and could not delete existing images.


Overall was a nice morning and I got some more stuff to play.

Have a nice week!

Saturday, May 25, 2013

Today's work

Today's work was this:
 Placed connector pins on the two new "Speaky" band module boards and also the VXO's adjustable cap (very small inside the red square), still waiting for the toroid's and crystals to continue building. Top board is a standard "Speaky" module.


And this:


top board is going to be a noise bridge with switched bypass (unfinished), bottom board is a swr meter circuit for the new antenna tuner (reworked, finished but not calibrated yet).

Another work for today was to fix the car brand badge, some time ago it fallen of but a good friend gave me a spare one and this time I bonded it with two compound glue instead of the standard 2 pin press fit, I'm sure it will not fall anytime soon.
Yesterday I went by to Lisbon and although always bellow the speed limit looks like I smashed a small bug...

...that's called dead bug style building...

Have a great weekend!

Wednesday, May 08, 2013

Thermal paste

What to do on a Sunday afternoon and your computer gets a little on the hot side?....and you just find out that the thermal past between cpu and dissipator is worn out..?

First you test with aluminum foil:

...and fails miserably...

..then you remember something about chemistry and "Fluor" supposedly is a nice conductor but toothpaste has a tendency to dry out...no problem: just add some silicon based gel or a petroleum derivative like the following product to remove cloth stains...

Mix on a 50/50 proportion, or 70/30 or...whatever......put on the CPU (careful for not to spill on the sides) then assemble everything again:

first the dissipator

then the fan


Now test it!:


 ..before the toothpast and supergel mix it was 2600RPM and around 70ºC

I'v been running over a week on this mix but eventualy one of this days will place a proper thermal past.... next experiment is to find a catalytic converter for the car to run on water! :)


Have a nice week!

Monday, April 01, 2013

New bands

While some people over here were applying for access on the 5Mhz band, our telecoms regulator "ANACOM" on a bold move just gave us access to another 8 bands in the HF spectrum.



I think this is a shift from the classic deny first, allow latter paradigm that is so classic across all sectors of society.

The new bands in Portugal are as follow:

455 Khz
600 Khz
4 Mhz
8.865 Mhz
9 Mhz
10.245Mhz
10.7 Mhz
21.4 Mhz

All modes are allowed. This is of course on a non interference basis, hams are primary users.
Beacons are welcome using low bandwidth modes.

Frequency shift is allowed to a maximum of 15Khz deviation



Output power is not regulated yet but probably will be around a maximum of 17dbm to keep things even with the other allowed bands.


Let's hope this new bands get adopted all over the world!

Sunday, March 31, 2013

Backlog...

When you try to multitask on a single tread then for sure something gets behind...

Here some projects tested but lacking a proper finish touch:

Light TX and RX pair:

Work's but didn't tried yet with a magnifier glass to increase range.

A BITX 20:

Needs the front panel drilling and now the front end transistor that was needed for another project.

An 6m downconverter:

then used as a test board for VHF receiver using some BITX 20 modules.


An SWR meter board:


..and the "display":


...Still unboxed.

A full HF transceiver:

 Working but never QSO'd. Will change audio path and need to put the low pass filters.

..many other projects still waiting conclusion most of them just need a box...

Think I have "work" for the next decade!


Have a nice week!












Thursday, March 28, 2013

Got this...

...in the mail yesterday:

...thanks to my PayPal account!


Those are 100 units of BB909B from DSI and about 50 (not exactly counted) BB909A from Philips.

The idea is to place them to work on the Speaky band modules replacing original BB409 varicaps that I can't find at reasonable prices.
I don't know if these "replacements" they will work but they were relatively cheap and can always be used for something else.

Here's capacitance versus reverse voltage on the "Speaky" BB409 units :

And here for the BB909 :
 

  They almost match...

I measure some units received (both BB909A and BB909B) and seem to match the datasheet values, the Philips ones have a little higher capacity than DSI make.

Still in need of the toroids...


Saturday, March 16, 2013

Standard diodes for RF switching

This idea of pressing ordinary diodes for RF work is not new, many LED's are working as varicap's, some diodes are protecting antenna front ends, other are working as zener's for transistor biasing and the list can go on...can you imagine that some diodes are even working as rectifiers?!!!...

 Now, this idea come because I have some (8) band modules to build for the Speaky and each module uses 4 PIN diodes, so, that's 32 diodes more than the ones I have... or for the mater, the local electronic shop.

(PIN diode is BA479 on the schematic)


Using ordinary diodes for RF switching is nothing new, many circuits use them.... but are they good? Or just reasonable? I had to test for myself!

Built a small circuit: the diode being tested in series with an 82pF capacitor and connected to an C meter. By placing in series I avoid any possible influence on the meter measuring method by DC blocking with the series cap, anyhow I think the measuring method of the multimeter is by impedance, injecting an alternate signal, and not by capacitor charge.

Here's the measured and computed results from the series association:



Light blue/grey is capacitor impedance above 500 Ohm, less than that and gets to close to the usual 50 Ohm influencing circuit performance. That's the importance of having a very low diode capacitance for RF switching. If signal is of high value it's also needed a diode with high forward current to keep things linear.

So, from this simple test results, and if you go bellow 28 Mhz, the 1n4148 is probably a safe alternative for RF switching. Interesting is also the yellow LED result by would not use it in circuit due to voltage drop.
I don't know what was the issue with the Germanium diodes, didn't investigated further since I was more interested in Si type.

 In the 14Mhz band module I built for the Speaky I used 1n4007 and 1n4148 without noticeable issues, let's see if it doesn't mess things with more modules in parallel.

 Just a side note:
BA479 diodes have an capacity of 0.5pF at 100Mhz (from datasheet), 1n4148 have 4pF at 1Mhz (also from datasheet), so, if you go the VHF side I think the only way is to use real PIN diodes for RF switching.

...now I have to find alternative varicap's and ferrite cores...

Have a nice weekend!





Thursday, March 14, 2013

Reader alternatives

I use google reader service to keep up with blogs and sites I normally follow.
It suits the porpoise and it's easy to work with, plus it's web based so I can keep up with followed blogs/sites as long as I have network access and a browser.

Here's a screenshot when all the news for the day are read:





(no special order in the blogs list, except mine first :))

Now the problem is: Google will decommission this nice web app in July first.


I wonder what software fellow readers use to read blogs/feeds/site feeds.

Of course I could get an XML/RSS parser lib and make a small hosted app for the purpose but time is already short for soldering and I put soldering first in my free time...

I'm open to ideas, preferably web based, but I'm considering also Linux based ones also. So let me know your opinions!

Have a nice day!


Thursday, January 31, 2013

Transparent magic smoke

Yes, not blue, not black or even white! Transparent, which only adds a layer of difficulty to find the leaked bottle...

I was trying to find the instability on 40m when I think I overdrive the "Speaky" releasing some smoke, OK it was not actually smoke but for sure something bad happened and now although it looks like I have transmission signal (didn't tested any longer) I don't have reception (but have audio) and I can ear the mic audio in the output speaker... something I couldn't earlier, so it can't be that bad....

Without further testing I dare to say that the problem is near pin 24 (see schematic,) be it further down or up on the tx/rx switching part. At least T30 isn't conducting during RX, that's why audio bypasses to the balanced modulator and I can listen to it on the speaker, so in that order of idea the balanced modulator is working also.... that leaves T27 to be a good candidate to the recycle bin....



Eventually it can be one of the switching diodes reversing near the mixer (not shown in this part of the schematic) but I would bet more on T27...

Well, more fun for the weekend...

Monday, January 21, 2013

Black out

Saturday morning, I wake up with some strong winds, the weather report was stating a red alert (second most dangerous) for most part of the country including Leiria were I live and Peniche, my parens, the predicted top wind-gusts were to be around 120Km/h. I went to the shack, hoping none of the antennas would fly and I could copy fellow blogger Bas (PE4BAS) activating a castle in the Netherlands, a quick tune around on 20m but no luck, after a little bit experienced a power outage, I could had switched to battery backup power but since I told my parents I would drove to their home decided to stop radio activities.

As predicted by the weather report, wind was really a bit on the strong side so decided to postpone the trip for latter in the afternoon hopping condition improvement.

When I bought my house my priorities in getting furniture were: a good bottled gas water heater, candles and a fire extinguisher....
The fire extinguisher is a must due my nature to make things leave some smoke, specially cooking...
Candles; When I was a kid an lived in Peniche it was normal in windy days to be left without electricity for some time so we had always candles and petrol powered lights. I've not experienced many faults now in Leiria but I like to be always ready.
A good water heather; well I'm not Finish (no offense) so I don't like very much of having a cold bath and sauna is not a tradition here also :)

Time went by and electric power wouldn't came back, so I hit the road to my parents. Wind was already lower and I thought I could make a safe trip, especially since my little daughter would come with me.
While preparing to the road trip I thought of taking the portable VHF/UHF radio, just in case, instead took the Swiss army knife, for sure much more handy in case I have to stop for some fallen tree of road debris.

Here's a nice quote from KE9V about a similar subject:

"...In a complete meltdown on a national (or global) scale there would be no one to call for help. In that case, I suppose two-way radio could be used to confirm that folks a thousand miles away are just as screwed as you are?..."
I think the quote says it all...
The brighter lights during my road trip to Peniche were my car lights, all villages until very close to my parents were all in a black out from the grid and the road was full of small debris from the trees, luckily fireman had already cut'd all the trees that had fall on the road during the morning high winds.

Electricity eventually returned to Leiria on Sunday morning, lucky me that my parents didn't experienced the power outage so I had a comfortable Saturday evening and a nice Sunday morning. From what I heard in the news there are still some small villages without power and even water.

Another side effect of this storm was that the antenna mast at my parents didn't hold the strong winds, it was a hardware corrosion problem, Peniche is a peninsula just in the path of the salty Atlantic winds, no metal holds good for live. Have to put a new mast next week.

Here's a video with some photos of the storm and damage in Peniche:


Now as I'm writing this post back in Leiria the water is getting low pressure, just as I predicted. This afternoon I bottled some water just in case :)
Let's hope it's only temporarily. Else I have to go to the river :)
..now there's absolutely no water, f"#$%!"#$#", getting better every minute...
...No all is bad, temperature is not going bellow 13ºC, people in northern latitudes are worse in this matter!

p.s.: There's a second QSO in the log using the "Speaky", this time the "victim" was IZ8GUU whom I answered the CQ on 17m.


An update list to do on the "Speaky":


Add heat dissipation to the final transistors.
Check audio compression/gain issue
Trim PA bias
Calibrate internal power/S-meter
Tighten cables.
Optimize IF filter bandwidth, now its a little wide for my taste.
Rebuild 40m bandpass filter, it works but trimmers are on the lowest capacity setting.
Add 20, 15 and 10m band.... 30,20,15,12 and 10m band




Have a nice week!



Have a nice week.

Monday, January 14, 2013

My new rig...

My first rig was a Kenwood TS-50, at that time it wasn't cheap but it was the cheaper rig in the market (new). It has been serving me nice and I still own it.

Now, after learning a little bit more about the hobby, made me realize I needed something different....


















OK, I know, it's probably a little on the expensive side but think about the joy of operating this little rig, and when you made a QSO you can tell with all the pride the model of your equipment and talk about all the bells and whistles, you can even mention it can make tea and toasts...

 It's for sure a pileup breaker...besides the bank account...


So without more delays....



....here it is....

....my new rig after the first successful real air transmission copy on 40m band...
It was with about 1m of wire connected directly to the first mixer amp since I haven't found yet the issue in the bandpass filter or in the 33Mhz low pass part (another possible candidate for the problem)....

(an old photo but same model)



Will keep debugging the next few days but at least half the rig works!!! I'm happy!

Saturday, January 12, 2013

Hot tip

..Ok, I fixed the soldering iron heater, eg: bought a new one, for the price I could have bought 4 cheap soldering irons but probably would not last the same time so I stick with this one since I'm already used to shape and size.

After getting again some heath from the soldering tip I finished re-cabling the Speaky, minus the external cw key but will solder those 3 wires in a near future.


Also a better cable routing will be finished after getting this QRP "beast" to full working condition :)


I powered it on and kind of worked..... have noise, good! Had a little problem in the frequency display, I programed it wrongly and the most interesting/strange stuff is when I disconnect the counter signal input the radio enters TX mode. I changed nothing and now it's OK on that issue but now sometimes it doesn't count....go figure, not critical for now I'm measuring VFO frequency with my external frequency counter....

All controls work but can't see much change from the pre-selector, more on this latter.
Here's an idea on the parts involved:





I can receive an 8 Mhz (the IF) signal from the frequency generator and a big signal on the 40m band (the only band module connected for now) transmitted from the FT-817 to a dummy load, still real air transmission got none so far. Will have to debug but I'm thinking that could be an issue from the bandpass filter or the first rf amp part before the first mixer, more debug on the next days....
Didn't checked transmission part so far.

Here's a global view of the receive part:


Have a nice weekend...

Tuesday, January 08, 2013

Cold heather


Yesterday I notice the soldering iron getting cold, immediately checked mains power (just looked at the soldering table light) and then I thought maybe the cable entering the iron handle got broken, twisted it a little bit and looked like the problem was over.... today I continued re-cablling the "Speaky" and at some point the soldering iron got cold again, this time it didn't resuscitate....

...and yes I checked continuity on the element...open!
 It was a "good" friend for over 8 years...now I have to buy a replacement heather element which is roughly half the price of a new iron....


...and you still have to have another iron to solder the new element.

One thing that is lasting less than expected was the new tip I bought two years ago

the original one and the one afterward lasted much lounger, probably their reducing manufacturing costs or outsourcing...




Monday, December 31, 2012

Late Santa

For me at least... but it finally arrived...



OK, it's not the latest greatest, it's not new, it's only good to 10Mhz but it works and was within my very very small budget, after all this is a hobby without income.
It has the advantage of a very simple circuit internally and comes with schematic and manual, something I should had thought when I bough the piece of crap of the "Kiotto/Ez Digital/Goldstar" oscilloscope unit.

Anyhow it's only needed for now to check some low frequencies wave shapes. I've been building without an oscilloscope for the past years, only in rare occasions I needed one, in my opinion an spectrum analyzer is much more useful...maybe one day.
 


Have fun!

Saturday, December 29, 2012

Some changes

I'm doing some changes on the blog layout, hope you like!

Also removing some stuff from the main page an putting it on static pages.

...if you don't like, just say so, if I will change it, that depends....

Sunday, December 23, 2012

Happy Birthday...

...to the transistor...

...and to myself.. (a little bit younger than the transistor)...



...photo taken some years ago on a field day

To celebrate the event and the "end of the world" :) this week I built an VFO with my age...

...from 73 Magazine, December 1972 (p114). It worked first time, although I just built the VFO part (Q1,Q2,Q3) there's no reason the buffer/amp part wouldn't work either. The design in itself is very interesting on the Q1 bias part, which is provided by Q3 to keep a constant output level.
As always I changed things a little bit, used 2n3904 transistor but almost any other transistor would work, with the exception on the one of the first photo in this post :)


Season greetings!







Thursday, November 29, 2012

New dummy load and the BNC problem

While making a small impedance bridge I came across a small issue in one of the female BNC plugs, the central pin would turn/rotate while being attached by a male plug, I sorted the issue soldering a strong wire from the center pin to another plug since that was according to schematic, a pcb island preventing rotation and anchored would be another solution.

Now reworking my UHF capable dummy load ("Cogent" mints box) to a new shape  (top one on the picture)....



...the same issue arrived making me break one of the eight 100 Ohm SMD resistors (4 || 200 series), in the end I reworked all the load, because I was out of 100 Ohm SMD, to tree parallel 150 Ohm 1/4W carbon resistors. Probably will not go to UHF but goes nice to high VHF.

In the end this was the result:




Not pretty, but for now it works...

Another issue I got due to the poor manufacturing tolerance and construction on BNC plugs/adapters is this:



 The middle pin is just press fit on the stripe line between the two female plugs of the T adapter.
It failed probably after the second insert in the dummy load, one advantage of this happening is that if you made a small coupler link you can make a bird style plug...

...always optimistic but next time will have to get a better brand of BNC's.




Monday, November 26, 2012

Random projects II


Between old projects getting finished, a lot more left behind, even more get in the horizon...

...I finished (for now) the AD8307 power meter:

 


 it was rewired in the inside and placed the input signal on the front. With the switch on this position it indicates the internal battery voltage, 9V, still good.

I also placed a rear input for the companion DVM:



There's also the option of using the front panel plug (on the DVM):



Get back to the midle picture... notice the DC motor and the IR slot sensor, had this recovered from a cassete player and a scanner and will proably be used in a NBTV mechanical receiver project I stunbled upon this week...


And when you don't have plugs for 9V bateries, just grab a used one and recover the top, easy:



Not all 9V batteries are equal but you can recover the plug from all of them.

Here's an idea for a measuring grab plug



It works but I have to get a stronger clip...

Some time ago I decided I would only buy new components when stock is empty or can't be recovered from old boards, truth is: I can't remember last time I bought components....hum...it was 2 days ago: 1N5711 diodes, had none and found none in the pile of old rf boards. It takes some time searching and recovering but no money is spent and you can always say: it was junk before, now it's a transceiver :)

Have a nice week!

Wednesday, November 14, 2012

Reinventing the wheel

Reinventing the wheel....



Will post more details as soon as I finish this prototype.

Monday, November 12, 2012

In the oven

Some random projects awaiting conclusion....


A new coil for the antenna tuner...
 A "configurable" bridge


And here's what happens wen you have to many broken printers around...

video


....probably a future micro CNC machine...


have a nice week!