Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- BITX20
- Messages
Search
Re: Need a video on ubitx troubleshooting
On Wed, Jul 18, 2018 at 07:52 AM, Richard E Neese wrote:
I have a ubitx v4 it was workign fine on my 12v 3 amp power brick all fo a sudden whip transmitting the unit shut off and cam back on.Mine did that, too, because the current draw was too much for the PS, and the PS turned itself off and back and on.? That can happen (at least in my case) on lower bands with a bad antenna mismatch. I did not have further issues like you describe. |
Re: RF power chain mods and improvements..
Sadly based on the data sheet I got some MPSH10s and as reported they didn't perform as expected.
The devices I found worked better for me are: 2n2222A(to18), I tried PN2222 and they?produced less power (better than 3904). 2n2219A,? the same as 2n2222A (they are the same die in different package) 2n3866 2n5109 I also tried a pair of irf510 as drivers with suitable mods for bias and they worked fairly well. The transformers for predriver and driver were less than optimum using those.? ?I also tried the 2n6661As and they were about the same as IRF510 and? for those that might consider it 30* the cost of IRF510, and 9* the cost of 2n2222A. Others that might work if you have or can find them are: MRF495, 2sC799, 2sc1306, 2sc1307, 2sc2166 Most of the effort to get not more power as you will get that but more even power ended up with changing the transformers for better impedance matching at higher frequencies.? My goal was 10W plus or minus a few and decent power at 10M. If your pushing for more power in the 80-17M range the 2n2222A is a winner? in the driver and pre driver along with bias changes already discussed. Allison |
Re: Low output Bitx40
Mucking with RV1 could easily and quickly blow the IRF510.
toggle quoted message
Show quoted text
Whenever adjusting RV1 (the IRF510 gate bias voltage), you should be monitoring? the drain current into the IRF510 (12v into PA-PWR1) with an ammeter. RV1 should be set for 100ma and no more (with no audio into the mike), it's very touchy. At that point (100ma) the IRF510 is just starting to conduct, a little bit more and it will be several amps. I'm a bit surprised it stopped at 1.6A, perhaps you have a weak power supply, could have been 10A. Assuming 1.5A going up as heat in the IRF510, that's 12*1.5 = 18 Watts into a very inadequate heatsink. Will be smoking hot. This RV1 on the Bitx40 corresponds to RV2 and RV3 on the uBitx (there's two IRF510's on the uBitx). Same rules apply, don't mindlessly twiddle those pots or you will blow the final. Should be 100ma into each IRF510. Twiddling R136 on the Bitx40 and RV1 on the uBitx adjusts the drive level into the transmit pre-amps. Somewhat less dangerous, as it probably won't cause the IRF510's to blow across the room. But turning up the gain too high there will cause distortion in your transmitted output and you will be splattering across the band. On commercial rigs, this is much like turning the mike gain up too high. When going for more power by adjusting those pots or increasing the voltage into the IRF510 drain or when going to long duty cycle transmissions (perhaps digital modes), a good idea to check if the IRF510 heatsink is getting hot.? If it's too hot to hold your finger on it, that's too hot. Jerry, KE7ER On Wed, Jul 18, 2018 at 07:07 AM, Allen Woolfrey wrote:
RV 1 set at about 30% on arrival.? Adjusting to full CCW raises draw to about 1.6 A on PTT, with no change when using mic.? Reset back to about 30%.? Also, adjusting R136 has no effect. |
Re: The new uBITX boards are here
Hi, I am not Mr Farhan, am just a user and an advanced qrm maker. As for ' Problems: great carrier in SSB mode TX, more then modulation speech signal!' I believe you should move up or down the BFO as it seems to be within the bandwidth of the filter. Most probably your modulation would sound extremely muffled. Il 18/lug/2018 10:27, "George via Groups.Io" <rx3arg=[email protected]> ha scritto: Dear Mr Farhan |
Re: Low output Bitx40
R136 with Bitx40!
toggle quoted message
Show quoted text
1: Power connector all wires connected properly ? 2: RV1 at center ? At 18-07-18, you wrote: Thank you for quick reply. |
Re: Low output Bitx40
1: Power connector all wires connected properly ?
toggle quoted message
Show quoted text
2: RV1 at center ? At 18-07-18, you wrote:
Thank you for quick reply. |
Re: Low output Bitx40
Al, check the electret condenser mic element soldering. Polarity is important.
toggle quoted message
Show quoted text
Raj At 18-07-18, you wrote:
Just finished wiring my bitx40. |
Re: Low output Bitx40
Just finished wiring my bitx40.?
Draws ~350ma with PTT, but no change at all when yelling or whistling into mic.? (Dummy load present at all times, so don't suspect final blown.) I see lots of discussion around this issue, but would appreciate advice on how to troubleshoot. 72/3, Al - va3iaw |
Re: receive works great, but no trans power,
#ubitx-help
That strap could cut Q90-base out of the circuit too, in case that causes RX spurs.
toggle quoted message
Show quoted text
Probably OK to leave the back-to-back diodes in there near Q90-base (to the left of C80) during transmit, as I doubt we have much more than 0.1vrms there. Unfortunately, I've got a very long list of stuff to do while the weather is good. Fiddling with the uBitx isn't on it. Jerry, KE7ER On Wed, Jul 18, 2018 at 03:53 AM, Gordon Gibby wrote: That would make for a very useful experiment! ? If you try it, let us know what you find out! |
Re: Need a video on ubitx troubleshooting
Check voltage at R104, should be 0v. Sounds like CW is on!
toggle quoted message
Show quoted text
At 18-07-18, you wrote:
I have a ubitx v4 it was workign fine on my 12v 3 amp power brick all fo a sudden whip transmitting the unit shut off and cam back on. Now the reciever is working fine but when I transmit I het a loud carrier with a hum to it and no audio output ... I figure something in the transmit section went bottoms up but looking at it with a usb based microscope I see nothign blown on the board no bubbles on chips and no broken or burnt wires. |
Need a video on ubitx troubleshooting
I have a ubitx v4 it was workign fine on my 12v 3 amp power brick all fo a sudden whip transmitting the unit shut off and cam back on. Now the reciever is working fine but when I transmit I het a loud carrier with a hum to it and no audio output ... I figure something in the transmit section went bottoms up but looking at it with a usb based microscope I see nothign blown on the board no bubbles on chips and no broken or burnt wires.
any input would be helpfull |
Re: receive works great, but no trans power,
#ubitx-help
Gordon Gibby
¿ªÔÆÌåÓýThat would make for a very useful experiment! ? If you try it, let us know what you find out!It¡¯s possible that different transistors have different reverse (base-emitter) break down voltages, which would dramatically change the amount of energy deposited on the base-emitter junction by a strong signals.... I just don¡¯t know enough about the devices
to say for sure.
|
Re: #ubitx #ubitx-help Not able to set up extension switches using CEC firmware
#ubitx
#ubitx-help
Daniel Conklin
Yes, I followed the instructions on the blog and the video. The values that should have been reported by the manager are not the expected results??
|
Re: The new uBITX boards are here
Dear Mr Farhan
As about me for several days I was asking for help as I've lost the original soft for scale and control of the Si5351. At last I've? find HEX file by KD8CEC and I am happy that it works!( Used XLoader). But till this time did not find the original file and besides this I am not the Arduino specialist. A lot of words but no FILE and how to load it! To my mind the R50 feed back of the Q70 should be raised to 820K to raise collector U from 1.8 to 6 V - not to over load it by strong signals.? Problems: great carrier in SSB mode TX, more then modulation speech signal! What is it? to use only in reception mode? The final 12 MHz filter is too wide and do not have 6/60 dB features, + some out of channel signals! But stii very simple and original transceiver not noisy with good sound! Some raising of the price of something 140-150 will not be too much for it. Best regards to you and your team 73! George UR4CRG/RX3ARG |
K5BCQ click fix 2nd generation installed
#ubitx
W7PEA
I didn't see pics of this in the site, so I thought I'd share mine. Continuity tests all look good. But, man tombstoning those surface mounts was hard! I Now understand why there was a REV 3. :-)
|
to navigate to use esc to dismiss