Wednesday, June 11, 2014

QRG - Trevo

Yup, it's possible to build a complete radio using only an multimeter as test tool but to know the exact frequency it's more practical to use a frequency counter.

Got myself a frequency counter kit, it will help me "debug" the VFO:


Now i'm on the 80 and 20m band (9 +/- 5.212)

Have a nice day!

Thursday, June 05, 2014

The "Trevo" works

Ok, I don't know in what frequency it his receiving, only I got my first copy of Morse signals from the ether!

The reason I don't know the frequency is simple, the only test equipment used so far is a multimeter.
After trying to figure it out the frequency of the VFO (I was suspecting that I could be receiving in the 40M or 80M band) I fired the qrss transmitter kit and set it for 3.580 Mhz, after tuning the VFO got my own test transmission (I was receiving some amateur Morse before).

The VFO (lower right on the image) is not the final design, just a quick lashed up design without great stability. Tuning is made by a varicap and a trimer cap, the two blue trimmers are for fine an coarse frequency set.



The only problems so far were:

* Incorrect publication, on the original article, of a component value on the bias of the BFO oscillator transistor which I discovered quick; the measured voltage was two low for bias and had reception for a second or so (after power on) before loosing it (was testing the BFO/product detector at 4Mhz since there's powerful AM stations around, now the BFO is back on 9Mhz)

* Thermal shutdown of the LM7912 (I'm using it so in the future I can add a 2n3055 with collector to ground) occurred on the makeshift power supply after some time of power on, now with more modules have to set another design to power the transceiver.

* Incorrect bias of microphone on the connection to the balanced modulator (still have to find out how a elect mic element does not needs power to give signal)

Work to be done:

* Decide on the VFO design
* Finish the transmit section
* Finish the band pass and low pass filters
* Adjust everything

That should be more one or two years at this rate!

Have a nice weekend.

Monday, May 26, 2014

FT-102 full line on desk

I finally had some time to assemble and test the new bought accessories to the FT-102.

Here's the result:




Now only some "minor" issues:

1- The HF antenna is broken (nothing to do with the radio tough)
2 -The accessories bough came with extended feet, the FT-102 didn't
3 - There are 2 birdies generated by the external VFO at 100Khz and 200Khz mark
4 - There's an offset of around 500Hz between the external VFO and the FT-102 counter (assuming one of them is correct, could not beat against WWV to confirm since the antenna is broken, see point 1)

How to address the issues:

1 - When I have time will fix it (not using this shack at the moment)
2 - Asked for the price of a pair of extended feet (got the reply while writing this; 5 GBP)
3 - Will investigate cable routing (signal is picked up on the antenna port)
4 - When I have plenty of time will adjust the thing

Another view of the setup:



Didn't tested the antenna tuner, assuming it's working.

Have a nice week!

Tuesday, May 13, 2014

New transceiver - Trevo

No, it's not the latest from the "East", it's not the latest from the brand that makes cooking ware.... it's simple the "Trevo", a new transceiver I'm building.

It's made in Ireland, were the water is free, (not anymore), by a Portuguese using mostly schematics from the rest of the world.... it can't go wrong....

The idea will be to have a medium performance transceiver for the everyday use, using some classic blocks without big fancy stuff. I'm building in blocks that at anytime can be changesd or replaced, also trying to use common components without compromising too much the performance. Most of the signal switching is done using relays (I might regret this in the future).

So far I made the following parts/modules:

*The BFO oscillator on the left, on the midle the mixer (ADE-1) and on the right the audio pre-amp chain. Isolated below, and still in the making is the AM detector

 *The IF amplifier chain on top, below on the left, the IF filters, one AM one SSB one LSB and one USB at 9.00 Mhz. On the right the first RF pre-amp and the attenuator.

*Bellow the audio amp on the left and on the righ just a makshift power supply, on top left an experimental mixer.
* The bandpass filtering section

* The mic amplifier on the right (741), SSB and AM modulator (by unbalancing) midle and left (MC1496).


Regarding the schematics, when I'm happy with the performance I will post them...just wait.


Since all transceivers have names/model, decided to cal this one "Trevo"; it could be the acronimouns for "Transmiter Receiver Evolution".... no, it's the Portuguese word for Shamrock which is one of the symbols of Ireland. I hope it makes sense....




Have a nice week and good luck!



Thursday, April 24, 2014

PRC-239-6X

Some time ago I bought one of this radios:


A military PRC-239-6X, 6m FM, not that I needed one just because I found it a fun design radio and was relatively cheap.


View of the power supply/regulator module and front panel:
And now the back with the belt support:

I also have the mic and tape antenna:



Since it was powered on probably 2 times , although it still works I might recycle it, at least the box for something else.... maybe one of this days.

Have a nice weekend!


Wednesday, March 12, 2014

Full line

....I know, wasn't thinking in getting more appliances, only built my own radios.... couldn't resist:


 Some years ago decided to have an FT-102 radio and acessories line, bought the antenna tuner first, after some time could not get hold of an FT-102 so sold the FC-102....a few months latter bought the FT-102....

After some long years of wait finally have the missing parts, all in one go: FC-102 antenna tuner, FV-102 external VFO and SP-102 speaker.

The bad parts is: bought in Portugal last time was there and arrived after I returned to Ireland... oh well... will have to wait a litle more to connect all things together.

Here's the lonely FT-102:



For now! 

Have a nice week!

Friday, February 28, 2014

GE 3-5976A CB in the shack

  Alongside with some other radio equipment, the GE 3-5976A walkie-talkie, was, when they come to the market, a big eye catcher for me.
Unfortunately at that time I was teenager and money was short to buy one.
Now money is still short but the price asked for second hand units it's way smaller, almost free, no one uses them anymore.

I don't do CB anymore but decided, as nostalgia, to buy two units, these ones:

 

They only come equipped with one channel out of three (channel 14, 27.125Mhz).
Tested the units doing a QSO with my daughter. She had a lot of fun and they are perfectly working and in good condition for the age, more than 25 years.
Serial numbers are 000051 and 000048 with date code 5451...whatever that means.

For the future, might use one of the housings for a 20m band portable Bitx or as an 10m AM portable rig. For now it's just for decoration.

Have a nice weekend!