BITX20 - 24. PA part 2... the story continues....

Well, it has been a long while since the 2 criteria to work on the bitx20 both were valid....
A) I have to feel like it....
B) I need time...

But as i have the week off.... i picked up the project box where the Bitx20 is in and opened it up.....
I took out the PA and started to look what was needed.....

I left off here.....

So i grabbed the manual and started to work with the dreaded coils i had to make......
Fortunately I did not have to make trifilar's, just bifilar and singles, which is a lot better.

So after a bit the board looked like this.......

According to the manual you are done at this point.... but i already stated that  the manual is a bit quirky and not 100% correct due to Indian>English>"Dutch understanding" translations.
If you look closely you will see that a 220pF capacitor, 0.55uH coil and a 1N4001 are missing...
Also a 100pF, but you cant see that due to the heat sink being in front of it.
On the top part you see some missing components as well, but that is only if you wanna use a higher voltage on the PA (or actually on the IRF510) then the standard 12 volts. As I intend to use this with standard 12v (or actually 13.8), I choose the other build method described in the manual. few less components.. (diode's resistors and an lm317)

Now getting back to the non explained missing components.........
This is a mod that was allready added to the PCB and also to the parts.... but not so good in the build manual....
In the mod section you find something , but not how to make this L2....
this is the mod:  Bitx20 Linear AMP mod
As it was still not clear what and how to do with L2 (found out later that it was named L2) i downloaded the build manuals of the Bitx20 ver 3b/c.
In there i found exactly what was needed....... 14 turns on a T50-6.
The diode is used in the version 3b/c as well , so i put it in and i have no idea if i should or not.....
I still need to do some testing and do the measuring to see if all is ok....
At least the PA/PSU looks finished now :)

Onto the next part !!! This will be a rebuild of the VFO from test version to something a bit more neat (Has to be done as well as 1 of my cats decide to chew on all the wires.... grrr)  and i will put the VFO and Counter in HF tin enclosures (or whatever they are called in proper English :) .....
Something like this :)

We're getting near something that will actually work!
Untill the next time!

73's
Alex
PA1SBM

BITX20 - 23. VFO working !!!!

Hello all,

Sorry for not posting a while, i wanted to do a lot , but first my gf came down with the flu and a huge cold.... and after that off-course i had to get it too , and i am still not 100% better....

A few days back i received this email which made me forget my flu/cold/headache and made me wanna jump into my shack and start to fiddle around with my bitx20 vfo again.....




I can only say one thing.... Danny , you are awesome......

As you can see , the vf0+bfo is now at a proper frequency!

I still have a tine problem to get the bandwidth (14.000 to 14.350) set correctly but i guess this is because of the coil i made (and me not having read the manual properly how to set it) . It is not the correct wire , much too thick. needed to adjust the number of winding's slightly too.

I'll do some shopping on eBay tonight to get the proper gauge... because off course ... i did not have any.... nothing near it either.... murphy's law i guess....


Again Danny, thanx for the sollution you totally made my week !!
Succes at last !!! on to the next Bitx20 battle!


73's
Alex

PA1SBM

The person guilty of getting me excited for the BITX20... PA1ED.....

Some things you just have to share..... This one of them....

The BITX20 virus was given to me by this HAM amateur that was talking on PI3ZDM, the repeater i always use when driving from and to work....

His callsign is PA1ED, and we all call him Ed.
By now he has build 3 Bitx20's i think.....
And like me he started a blog, so without typing to much here , if you wanna see some realy cool stuff... go look at his blog! It's realy worth it !

pa1ed.blogspot.com

Be warned though!! this site is highly contagious !! you will be building your own bitx20 in no time !

Don't say i did not warn you !

73's 

Alex

PA1SBM

BITX20 - 22. VFO ups and downs ....

Hello all....

It has been a long while since i wrote on my blog... sometimes live just gives you no chance at all do do hobby related stuff.....
I always try to put my gf 1st , then work, then the rest....
Unfortunately sometimes my work takes so much time that even the gf gets put back to 2nd place... and i have to make up for this... People who are finding them self in this same problem will know that it takes twice as much time to make the gf happy again then what is should have taken to keep her happy.

So back to tech stuff....
First of all, i had some people message me and talk to me on local repeater to help me fix my problem.
And one person with a question.

lets start with the first one....

john robertsApril 13, 2013 at 12:06 AM

Have you set up the IF offset on the frequency counter. from john GW0TBT

John... I so hoped this was the problem... :) unfortunately , it was neatly set to 0...

Then i received this question...

Вячеслав ВдовенкоApril 23, 2013 at 12:11 PM

hello
Сan you show how connect is new VFO (variable-capacitance diode) to the transceiver?
thanks

Not really sure how to type your name on my us-gb qwerty keyboard so i hope you can forgive me :)
I have not found this out myself.... as i am not at this point yet. I talked to PA1ED, and he said that it its really easy to see in the schematics.


So how about my VFO then....
Well it's still the same.... i went to a fair and i bought the stuff i needed and put that in. Still no proper frequency. At least now all parts are brand new and i can't blame those 2 trim capacitors anymore.
So now i really have to get into measuring every damn thing. This takes some time, and the 15 to 30 minutes i find these last few months will not give me enough time to really get this done.

I have a week off in a few weeks , and i hope to find a few hours to solve this.

As soon as i get stuff done, whatever the outcome i'll post it here off course :)

till then
Alex
PA1SBM

BITX20 - 21. PA part 1... the start....

So i said that this weekend i would finish my PA for the Bitx.
That was some nice wishful thinking. I build the first part , and i stopped when i needed to wind a coil.

Two other reasons that i could not finish the PA were a) my work and b) 1 of the coils which were in the kit arrived broken :(

well , its build untill here.....

More soon to follow......

73's

Alex

BITX20 - 20. VFO still not at the right frequency ....

This week, while i had the week off,  i have been busy mostly with rebuilding the attic. i bought my house 3 years ago, and the attic was one big room. It's now divided into a separate storage and a guest bedroom. but this is more for a different blog, back to tech stuff :)

I also had some time for fiddling around with the VFO again and i do not get the bloody thing on the frequency it should be at which is about 14.175 - 9.9953 = approx 4.180 MHz. My VFO is running at twice the frequency.

So somewhere there must be a weird thing i did wrong. I am very sure about that, but WHAT!?!?!?!
I started to check the components if i did not stick a wrong capacitor or resistor somewhere, but no luck so far. I also started to fiddle around with the windings on the coil, but the difference i get is too little for making up for the double frequency.

At this point i am staring blindly at this, so i have decided to give it a rest for a bit and start to build the amplifier section first. This again needs lots of coil winding, and oh my i love that so much.... not.... :)

So keep watching the blog. as that  section will be done be for the end of the upcoming week.... i hope :)

73's
Alex, PA1SBM

BITX20 - 19. VFO..stupid stupid stupid....

Just a little quick post which will show again why you need a proper guide/manual to build stuff if you don't know what you are doing too well.....

Today i came home early and while driving home i was talking on the repeater of Zaandam, where all of a sudden PA1ED came on... as you might remember he is the one who got me started with the Bitx20 and is also the one i talk to if i need a proper translation from what Sunil writes in his guide, to something what I as a dutchie understand. The conversation started like this.....

Me: Hey Ed, guess what, my IK3OIL FLL VFO runs at 14 MHz !! Woohoo!!
PA1ED: Ohh then i think it's broke... what did you do with it?
Me: Huh? What are you talking about??...
PA1ED: Well , unless you wanna end up at 24MHz, the VFO should not run at 14, but at 4 MHz....

Then as he said this , it hit me....the BFO runs just under 10 MHz... and you need to add that to the frequency of the VFO what will end up to be the frequency you use....
This was what Ed explained quickly as well as i was nearly at home..... So back to the drawing board ....

I will get there though.... just happy to have people correct me right in time before i really blow up things!
So again a big thanks to Ed! :)

73's

Alex

BITX20 - 18. VFO at 14 MHz....

Last Saturday i got my potentiometers which i ordered. WOW fast delivery this time from China. Just 6 weekdays. So needles to say I started to work on the VFO again.

The strange thing I had is that my VFO was at around 12 MHz. Which of course is too low :)
The only thing I could think off was the toroid I had wound to be wrong. After checking it turned out to be according to what IK3OIL writes in his building instructions......
Well almost.... it says to use 0.5mm diameter wire... which i did not have , so i used something slightly thicker... well twice as thick.....

As the instructions show that if you use less windings , the frquency will go up , i started to remove one winding at a time.... And i got it to get to 14 MHz!!
But as i had to remove too many windings to my liking, i decided to get me some 0.5 wire.
So that's now ordered, and as the eBay wrote me yesterday, sent allready as well :)

I checked all other components as well and I noticed that IK3OIL thinks that C8 needed to be 60pf ceramic, so as Saturday is a ham parts fair again , I will look for that as well.
I'm not really sure why this is though... the normal trimmer I used seemed to work OK.

I hope this all will "solve" my "problem" :)

Will keep you all posted... until the next post!

Alex
PA1SBM

BITX20 - 17. VFO first test....

Yesterday we had the "ROM" at "the lichtmis" Dutch amateurs will know what i am talking about, but as i have a lot of people and fellow ham's following me from abroad (which I'm really proud of, and thankful for) I'll explain what this is..... It's a small radio parts meeting. which has become a "must go to" for most hams in the Netherlands. Even though it's in the north part of the Netherlands, i always hear people from down south as well... This market is without a doubt one of the most fun markets to go to.

Well, anyway, i bought some parts which i still needed for the VFO. uhmm well, i only needed a 2k multiturn potentiometer (variable resistor)(blue thing in the picture)
This morning i started to hook up everything to see if it would work.... and it did....
For calibrating i need a 10k potmeter as we call it in the netherlands :) and i dont have any...
That's why you don't see a 14 MHz on the display yet. the vco is not hooked up yet
I'll be placing an order on eBay shortly after this post :)

Again i am getting a step closer to a working bitx, but there is still al bit to go... s-meter, agc...
But i think after the winter I'll be qrv on this set :)

UPDATE: potentiometers ordered :)

BITX20 - 16. Building the external vfo part 2

Ok, finally i got most parts now.... thanks to ebay :) ... i ordered about 1200 capacitors, and the transistors i had a problem with getting where i live, the 2N2369.

A HAM friend of mine provided me with the 2 trim capacitors. which were the last parts needed to fill up the PCB.

Next problem will be the 2k multi turn potentimeter, but there is a HAM fair next weekend again :)
And if i have no luck , another one 2 weeks after that. So i guess this will be easy.

When this is working, I'll start to put the bitx20 together , cause the last part is the PA part, which seems not that time intensive. so maybe this year it will be done. (Remember i never was in a hurry to build this :) )

BITX20 - 15. Building the external vfo

I ordered my bitx20 including the LCD frequency counter option.
At that point Sunil included a pcb for a vfo that works together with the frequency counter.

So i started to build this. As no components were included, you have to gather all parts yourself.
My component stock is no where near big , but with the basic stock i have, it almost filled the complete PCB

The components that i am missing are not uncommon ..... i think....
Just som capacitors, 1 coil, variable capacitors, diodes, etc....
So whe i am going to a small hamfair upcomming saturday, i hope to get al parts i need.
If not i still have some ham friends, or online suppliers that can supply me with the parts needed.

BITX20 - 14. The exciter is finished !

I had to make this a separate blog post.....
but the exciter is finally done....

Here it is :)

Now on to the PA part... yeah more coils :|

BITX20 - 13. The output driver

The output driver section was not hard.... even with the coil to be wound...
It was a bifilar, not a trifilar.... so that made it slightly less annoying :)

as this is near the end, i now noticed i am missing a few more things....missing a 100 Ohm and a 1k Ohm resistor. No Clue what i am gonna miss next :)
This for me is one of the charming things of the Indian package. Now if i paid the qrpkits.com price, i would probably mail them for every single item i missed. Now i just took them from my own stock.

As you can see... it is just a small part...

Measurments came out fine, so no worries there!

BITX20 - 12. Xtal section...

Ok , this was hardly any work.... 4 xtal's and 3 capacitors....
No measuring either....

Now there is only 1 section left on the exciter... the output driver.... with a dreaded trifilar coil @#$@#
No time left now to make it. maybe late tonight....

BITX20 - 11. Audio section completed

This was easy until i noticed that i was missing some parts.... I missed a 1uF capacitor, and i noticed i had a 10uF in my capacitors bag. I have done some reading in the part lists in the manual , but i think thy misplaced a 1 by a 10 uf capacitor... As any DIY person should, i took a 1uF from my own stock, and put it in.
The same happened for a .001 uF capacitor... again ... $100 including shipment... i am not complaining.

The only thing weird is that my Q10 measurements are a bit too much off for my liking so i will check those with PA1ED (yes he got his full license now!) and see what his measured value's were.
As they are not way off, I'll continue for now.

On to the XTAL section !

Edit:
Note:
For those who wonder why i now all of a sudden build a lot compared to the usual slow pace....
I treated myself to a few days off... :)

BITX20 - 10. BFO / Modulation section done.

ARRGHHH i was tricked.... well i just did not read stuff good enough...
There were 2 coils... one not that bad, but the other was the 3rd dreaded trifilar coil....
And i know that for the exciter board i still have to make one. (and 2 i believe for the PA)

Anyway , the rest of the build was fast and painless.... (except for the manual saying 50uF, and them supplying 47uF) (also a normal fitting potentio meter would have been nice)
So lets not complain :)

Measuring all showed me no weird things... Just the normal difference... measurments just never seem to be exact :)

Audio section is next.... And now i checked the list... no coils :)

BITX20 - 9. Building and meassuring the 2nd IF Amplifier

Oh how much joy building none coil parts :)......
So the 2nd IP Amplifier was done in no time..... and i enjoyed it a lot!

Does any1 notice the 1 resistor being a different color ????
Yes indeed , 1 resistor was not included in the complete package. a 4.7 Ohm resistor.
Luckily i had one in stock.

Measuring this part was fun as well.....
There is a Q3 and a Q3a transistor.... and in the manual they have mixed up the value's what you should measure. So this again is one of the quirks from the BITX20 kit.
So if it says Q3, read Q3a , and if it says Q3a, read Q3..... And remember that this is a $100 kit :)

On to the next part !!! (still has no coils ;) )

BITX20 - 8. Building the 1st IF amplifier

After finally having done the trifilar coils, i felt like building more :).
So i builded the 1st IF Amp as well last night. It's all very straight forward.
I do not expect any problems here. This is how it looks......

Again you can see that the transistors are "the wrong way around" to the masking on the print itself....
This is still due to the change of transistor type Sunil has put in his kits. From what i have read on his blog, the new v3 kits should have a proper masking again, but i am not sure.
I intend to do all the measuring after i get myself another cup of tea.... Luckily the whole test setup from last night is still on my desk , so i can start straight away. I do not expect anything weird here so probably the next post will be on building the post if part....

BITX20 - 7. Building and measuring the "First Mixer"

This is by far the most dreaded part for me.... I don't know why, but i just do not like to wind coils.....
So that is the reason i have been putting it off for so long.... But! i forced myself to do it and.....

TAADAAA!!!!
There are the 1st two trifilar coils. Thank god that was done. Putting in the 4 1n4148 diodes was easy , so now this very small section looks like this....

After this we finally could measure voltages on the last transistor of the vfo part, and that turned out fine.
On to the next part !!!

BITX20 - 6. Measuring the VFO

Just a small progress update on the BITX.....
A while back i build the vfo part and started to do all the measuring as discribed in the manual....
Unfortunately the value's described in the manual is no where near what it should be....
So i emailed an other ham operator who has build 2 already to see if my value's rang a bell....
And they did :) thanks PD1ED.

I am sure other people will have the same experience... So i will share this info as well.
Or, if you are into yahoo groups, do join the BITX20 group there. It's a real goos source of info.

Current drain, 34,8mA, not 44,4mA

Q5:
E: 7.21v 4.76v
B: 6.96v 4.87v
C: 8.48v 9.88v

Q6

E: 6.36v 3.99v
B: 7.08v 4.66v
C: 8.48v 9.89v

You can see how much the difference is and then, if not told you will start to worry like me.
(These are my measurements, please remember that they can differ to yours as components, testleads and multimeter's have various deviations)

Well , next weekend on to making transformers....

73's
Alex