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Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Hi Jep,

Well, if you have some components such as a germanium diode I suggest you build yourself a RF probe, then you can use the fluke to measure RF levels before and after transistors. See example:?
Perhaps You can mail order the needed components if You dont have them at hand. Or perhaps another ham in your town has them?

Best?regards
Jonas - SM4VEY
?

As already briefly mentioned, here at my "marine" location some 50 km North of Rome I only have a digital multimeter instrument, and by now (due to pandemia lock-down) there is no chance to move to Rome and access an oscilloscope or whatsoever... Let's consider that an exercise for emergency conditions: Use more the brain instead of sofisticated instruments :-).
Cheers
Jep
_._,_._,
Re: Better mic for ver 6.1

kbtgw
 

That is a ad for a 4 pin mic, v6.1 uses a stereo plug ?

?? Les,? K2TGW
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

Dale Parfitt
 

¿ªÔÆÌåÓý

For anyone that thinks they may be replacing the transistor more than once, you can cut single sections off of? SIP sockets and solder them onto the pads. Then? it is as simple as unplugging one transistor and plugging in another without the worry of lifting pads.

?

Dale W4OP

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Jep
Sent: Wednesday, May 13, 2020 12:59 PM
To: [email protected]
Subject: Re: [BITX20] Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

?

Hi Allison,
thank you for the comments. Luckily enough, R84 was not altered as I found full 12V on transistor collector.
At the end, an old TO5 metal-case BC142 came out of my "marine" junk box so I installed it immediately.
Needless to say, now the ubitx puts out its full power and works as it should. The precise indications by the Group have been fully effective.
Given the BC142 is a robust transistor and that now I know I could eventually replace it at once, I will not install protection diodes: You are certainly right.
Bests,
Jep

Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Hi Allison,
thank you for the comments. Luckily enough, R84 was not altered as I found full 12V on transistor collector.
At the end, an old TO5 metal-case BC142 came out of my "marine" junk box so I installed it immediately.
Needless to say, now the ubitx puts out its full power and works as it should. The precise indications by the Group have been fully effective.
Given the BC142 is a robust transistor and that now I know I could eventually replace it at once, I will not install protection diodes: You are certainly right.
Bests,
Jep
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

Jerry Robinson
 



nil sine causa accidit

Jerry



On Wednesday, May 13, 2020, 04:16:46 PM UTC, ajparent1/kb1gmx <kb1gmx@...> wrote:


Besides Q90 as possible failure if it fails shorted R84 tends to fail.
THats that little 10 ohm SMT that supplies 12v (nominal) to the
collector of q90.

So if the collector is at .5V (TX) then R84.

FYI putting protection diodes there is not a good idea as its also in
the TX path and diodes conducting on TX will make for harmonic havoc
and possibly poor audio.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

Re: #raduino #v5 #raduino #v5

 

Realized I forgot to explain how to select without touch:

1) turn on radio
2) press knob in briefly to enter selection mode
3) rotate knob to highlight the gear icon
4) press knob to select
5) rotate knob and press knob as need to navigate menu to select calibrations, and then touch calibration.


Reed
Re: #raduino #v5 #raduino #v5

 

If the debug version works, then you probably just need to calibrate. Gear icon to get to the menu, then use the tuner knob to select calibrations, and then touch calibration.


Reed
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Besides Q90 as possible failure if it fails shorted R84 tends to fail.
THats that little 10 ohm SMT that supplies 12v (nominal) to the
collector of q90.

So if the collector is at .5V (TX) then R84.

FYI putting protection diodes there is not a good idea as its also in
the TX path and diodes conducting on TX will make for harmonic havoc
and possibly poor audio.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Pat and Bill..,
you are temptimg me :-)
I have some old 2N2222 with metal case, gold in colour... That one should look like nice, a giant in the Lilliput town of the smd population :-)
Me too, I thing installing a couple of protection diodes is a good idea. Will do.
Cheers
Jep
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Bill I replaced Q90 on top of the board after removing the 2N3904. I just shortened the leads and bent them to fit the pads before tack soldering it in.

Skip Davis, NC9O

On May 13, 2020, at 11:05, Bill Cromwell <wrcromwell@...> wrote:

?Hi Pat,

I already know I have the Q90 problem with mine. I think the 2N2222 is a bit more robust but will install the protection diodes too. I haven't looked in mine..did you install the replacement on the bottom of the board or in the vacated spot left by the original part?

I will do the repair as soon as I locate my fire axe so I can remove the bad part.

73,

Bill KU8H

On 5/13/20 10:54 AM, pat griffin wrote:
The same thing happened to me a few years ago and I used a 2n2222 non SMD. It worked fine and I think it is still in there.
73, Pat AA4PG
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Ray,
Voltages are 12V on Collector and 0.5V, the same on Base and Emitter. So the Base-Emitter junction is shorted and that should explain not only the missing of RF-out, but also the reduced sensitivity of the receiver.
Thank you, again, have a good night, I wish you all the best
Jep
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

¿ªÔÆÌåÓý

Bill,
I think I installed it on the top so it looks like a water tank in a midwestern town hovering above the smd parts.? Bend the ends of the 2n2222 legs into little circles at right angles to the legs and solder those feet to the pads.
My wife took my fire axe away years ago.? Something about scaring the kids' friends.
73, Pat AA4PG

Pat Griffin
http://www.cahabatechnology.com/aa4pg.html

From: [email protected] <[email protected]> on behalf of Bill Cromwell <wrcromwell@...>
Sent: Wednesday, May 13, 2020 9:02 AM
To: [email protected] <[email protected]>
Subject: Re: [BITX20] Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help
?
Hi Pat,

I already know I have the Q90 problem with mine. I think the 2N2222 is a
bit more robust but will install the protection diodes too. I haven't
looked in mine..did you install the replacement on the bottom of the
board or in the vacated spot left by the original part?

I will do the repair as soon as I locate my fire axe so I can remove the
bad part.

73,

Bill? KU8H

On 5/13/20 10:54 AM, pat griffin wrote:
> The same thing happened to me a few years ago and I used a 2n2222 non
> SMD.? It worked fine and I think it is still in there.
> 73, Pat AA4PG
>
> Pat Griffin
>

--
bark less - wag more
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Hi Pat,

I already know I have the Q90 problem with mine. I think the 2N2222 is a bit more robust but will install the protection diodes too. I haven't looked in mine..did you install the replacement on the bottom of the board or in the vacated spot left by the original part?

I will do the repair as soon as I locate my fire axe so I can remove the bad part.

73,

Bill KU8H

On 5/13/20 10:54 AM, pat griffin wrote:
The same thing happened to me a few years ago and I used a 2n2222 non SMD.? It worked fine and I think it is still in there.
73, Pat AA4PG
Pat Griffin
--
bark less - wag more
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Jepp,

I cant let you go before I sleep peacefully! What was the TX voltages of Q90?

Raj

At 13/05/2020, you wrote:
Bingo!
Raj, David and Jonas you are right! Q90 on my ubitx seems to be blown!
Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

¿ªÔÆÌåÓý

The same thing happened to me a few years ago and I used a 2n2222 non SMD.? It worked fine and I think it is still in there.
73, Pat AA4PG

Pat Griffin
http://www.cahabatechnology.com/aa4pg.html

From: [email protected] <[email protected]> on behalf of Jep <giuseppe.cavarretta@...>
Sent: Wednesday, May 13, 2020 8:45 AM
To: [email protected] <[email protected]>
Subject: Re: [BITX20] Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help
?
Bingo!
Raj, David and Jonas you are right! Q90 on my ubitx seems to be blown!
The multimeter shows about 230 ohm on the junctions. I did not yet check the voltages but I did this:
Using a short wire and two thin pins I just touched the Base of Q90 and the cursor of RV1, thus I bypassed Q90: then pressing the key some RF out from the PA immediately pop-up nicely!?
Thank you all my friends for the kind and smart expertize!

Now, to complete the job the matter is...: I do not have a 2N3904 SMD at hand. Should I order it online or install an ordinary 2N2222 (non SMD) instead?
Well... I do not urge to have the ubitx?working tonight, so it is certainly best to wait and do a proper job.?
In the meanwhile, just to fill the present boring days, I will play with a single-tube xtal transmitter 1938-style :-)

Let me add a comment:
This is the first time I asked for help on this Group and I have been delighted by the quick, very kind and smart response of so many friends that helped getting out of trouble.
Truly amazing.
Thank you all from my deep heart.
Best regards
Jep, IZ0WIT

Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Bingo!
Raj, David and Jonas you are right! Q90 on my ubitx seems to be blown!
The multimeter shows about 230 ohm on the junctions. I did not yet check the voltages but I did this:
Using a short wire and two thin pins I just touched the Base of Q90 and the cursor of RV1, thus I bypassed Q90: then pressing the key some RF out from the PA immediately pop-up nicely!?
Thank you all my friends for the kind and smart expertize!

Now, to complete the job the matter is...: I do not have a 2N3904 SMD at hand. Should I order it online or install an ordinary 2N2222 (non SMD) instead?
Well... I do not urge to have the ubitx?working tonight, so it is certainly best to wait and do a proper job.?
In the meanwhile, just to fill the present boring days, I will play with a single-tube xtal transmitter 1938-style :-)

Let me add a comment:
This is the first time I asked for help on this Group and I have been delighted by the quick, very kind and smart response of so many friends that helped getting out of trouble.
Truly amazing.
Thank you all from my deep heart.
Best regards
Jep, IZ0WIT
Re: uBitx V4 for sale

 

OK
I'll take it - pics would be good before I transfer the money?

73
Lou KI5FTY



On Wed, May 13, 2020 at 9:21 AM John Veach <ke4d@...> wrote:
Lou, one works and the other is just the main board ? I think I blew the Radiuno on that one but I haven¡¯t messed with it in a long time. ? Just worked a guy on 20 cw with the other one yesterday. He was in NM and I am in Fl so it works FB cw. Never hooked up a mike to it. ? Email is ke4d@.... I can send you pics etc. also Paypal is best. Same address.?

Re: uBitx V4 for sale

 

If they are working units - I will take it

73
Lou KI5FTY



On Wed, May 13, 2020 at 9:05 AM John Veach <ke4d@...> wrote:
I have two V4 that are surplus to my needs. (V6 arriving this week). One with a Nextion display running KD8CEC software if I remember correctly that I use on CW only. I did put a four pin mike connector in the case but never acquired a microphone for it. Never hooked up the straight key jack just a paddle for cw. It¡¯s in an aluminum case I got from SkyCraft in Orlando and also has a 12 v fan built in. I will throw in the other V4 which has no display and I haven¡¯t looked at it for a while!? Going to list on QRZ but wanted to put them here first.? Will ship both U.S.A. for $100 ?

Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

I used another transmitter close to my v3 and blew q90.
Replaced q90 and all was good. Dave? kc2ipx

On Wed, May 13, 2020 at 9:18 AM Raj vu2zap <rajendrakumargg@...> wrote:
Also check Q90 EBC voltages. We have to eliminate a possible short of Q90 EB junction.

Raj

At 13/05/2020, you wrote:
>That you Ray, I will do that immediately.
>Jep




Re: Poor RX sensitivity, no RF out - #v3 #ubitx #ubitx-help

 

Also check Q90 EBC voltages. We have to eliminate a possible short of Q90 EB junction.

Raj

At 13/05/2020, you wrote:
That you Ray, I will do that immediately.
Jep
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