As I had mentioned earlier, the TinySA is not very suited for measurements like this because it doesn't have sufficient shielding. Shielding makes it expensive and heavy. The third harmonic must be breaking through the signal chain of TinySA.
Sounds like yours came from the same batch.
? ? ? ? ? ? ? ?- jerry
On 2021-06-20 07:16, Rafael Pinto [PU1OWL] wrote:
> Hi Jerry!
>
> At least I can tell you the Chinese LPF is consistent!!
>
> Mine just got here and, lo and behold, there is a 150pF cap on the 80m
> filter! Just ordered a replacement 1.5nF.
>
> Also, 40m is waaaay low on frequency, with the cut off at 5.2MHz.
>
> The 17m-20m is kindof ok-ish, with its cut-off just below 20MHz. There
> is a notch at the second harmonic (28MHz), so I'm not complaining...
>
> The 15m-10m is also ok-ish; the cut-off frequency is at 29.5MHz, so
> I'll probably have to take one turn of the inductors...
>
> 73 de PU1OWL
>
> Rafael
>
>
> Links:
> ------
> [1] /g/BITX20/message/89212
> [2] /mt/83355576/243852
> [3] /g/BITX20/post
> [4] /g/BITX20/editsub/243852
> [5] /g/BITX20/leave/10189903/243852/952924773/xyzzy
|
Jerry, It would be a very extensive effort. 1. Given similar power levels, a 2N7000 in place of the antenna relay should work. A few more transistors can isolate the rx signal path. This is the easier of the wins. 2. Timing. A particular sequence of things have to happen. On key down, the rx audio has to smoothly switch off, then the rx amplifiers power should turn off and the bypass caps need to be discharged, the tx circuitry has to power up. The sequence has to reverse on key up. 4. The LPF relays should be constantly powered up (even on rx). These may wear out the relays. Combining full break-in with multiband is an expensive and extensive option. The ubitx is a child of many compromises.
Has anybody tried to do this with the uBITX?? I have a qrp-labs QCX+ kit
that does it,
and I must confess, I'm getting spoiled.? I tried it with my
TS590S...nope.? Feverishly clacking relays.? Dug an IC706MKII out of the
closet- same deal.? Clack-clack-clack.
? ? ? ? ? ? ? ? ? ? ? ? - Jerry KF6VB
|
Has anybody tried to do this with the uBITX? I have a qrp-labs QCX+ kit that does it,
and I must confess, I'm getting spoiled. I tried it with my TS590S...nope. Feverishly clacking relays. Dug an IC706MKII out of the closet- same deal. Clack-clack-clack.
- Jerry KF6VB
|
Re: It'll never happen to me!
Well, the search continues for the loss in power, and thanks for the suggestions. I did examine R83 and C81 and the appear OK...certainly R83 measures OK and everything looks OK in that area. Thinking "what has changed from before", I even pulled the back-to-back diodes I added to K1 and rechecked, and that made no difference in output. This is a comparison, same power supply, same dummy load, same watt meter. Audio input was from a steady tone added at the mic jack. 30, 20, and 17 meters show the most dramatic losses. Any more ideas?
| ? |
? |
? |
? |
Power to dummy load |
? |
? |
? |
| ? |
? |
80 |
60 |
40 |
30 |
20 |
17 |
15 |
12 |
10 |
| Now |
SSB |
12 |
9 |
10 |
4 |
3.6 |
3 |
2 |
1.7 |
1.5 |
| before |
SSB |
15 |
11 |
14 |
9 |
9 |
8.5 |
3.5 |
3 |
3.25 |
I keep puzzling about how R82 fell off the board after the original event. No signs of heat or physical damage and I wonder if it was cracked or something. Would a different value from a damaged SMD resistor change the gain of that stage there? As delivered and throughout the test the value of RV1 is set for max output.
=Vic=
|
|
|
Hi Jerry!
At least I can tell you the Chinese LPF is consistent!!
Mine just got here and, lo and behold, there is a 150pF cap on the 80m filter! Just ordered a replacement 1.5nF.?
Also, 40m is waaaay low on frequency, with the cut off at 5.2MHz.
The 17m-20m is kindof ok-ish, with its cut-off just below 20MHz. There is a notch at the second harmonic (28MHz), so I'm not complaining...
The 15m-10m is also ok-ish; the cut-off frequency is at 29.5MHz, so I'll probably have to take one turn of the inductors...
73 de PU1OWL
Rafael
|
Re: Question re transceiver kit UBITX v6
Thanks for the encouragement Bob....Al
-----Original Message-----
From: Robert DiPippo, k1wyc via groups.io <bobk1wyc@...>
To: [email protected]
Sent: Fri, Jun 18, 2021 2:01 pm
Subject: Re: [BITX20] Question re transceiver kit UBITX v6
Al, I am 82 and I started in 1962 but kept up as I am a retired
professor with the subjects in Electronic Technology, Computer
Technology, Electronic Media Communications. You can service it.
There is only 12 volts and not the 400 and 600 volts or more with
tubes. Trace the 12 volts and 5 volts just as if you were tracing
the 400 volt line but without the shocks. You can not make it
worse so give it a try. We are all here to help.
73's
Thanks
Bob ,K1WYC
On 6/18/21 11:21 AM, alhill0728 via
groups.io wrote:
Thank you all for your
replies.
Unfortunately, I obtained my licence (VE3DLG) in 1963.? The
test was entirely on vacuum tubes.? I have not kept up with
solid state technology and at 83 years of age, I am unable to
do any trouble shooting of this magnitude.? I thank you again
for your advice ... I will try to get a new board.??
Al Hill, VE3DLG, Picton, Ontario.
-----Original Message-----
From: Curt via groups.io
<wb8yyy@...>
To: [email protected]
Sent: Tue, Jun 15, 2021 6:27 pm
Subject: Re: [BITX20] Question re transceiver kit UBITX v6
Let's troubleshoot and maybe its something simple.
You transition seems to have been from off to receive
when this occurred. Trace the path from 12 volt input
to the big 5 volt regulator. It could even be the on
switch that failed, or a wire fragment could have
created a short circuit, taking out the fuse. I would
check the path first with no dc input, with an
ohmmeter before connecting it to voltage. Sorry for
the extra adventure, and I am hopeful its something
simple with little damage. Do engage Evan as you
follow his deeper instructions.?
Curt
--
Connecting the classroom to the world via technology ??
|
Re: It'll never happen to me!
Hi Vic,
Remove one of the relay drive transistors and check it for reference as all on board will be from same spool.
If its is better then use that for Q90 and put a new one for the relay!
I used to do this for commercial rigs. Some rigs loose the PLL lock when they heat up and I figured the
gain in a loop was low. I just removed one from another stage and swapped them. Problem solved.
Raj
toggle quoted message
Show quoted text
At 18/06/2021, you wrote: Well, Raj, I just did that. I checked the Hfe of a 2N3904 with leads and it registered at 423, while the "3904" SMD devices only read 280, about the same as a 2N2222A, so I suspect this is another case of a supplier somewhere picking up any NPN and saying, sure, it is whatever you ordered! So I swapped the device with leads for the SMD and brought up the power a bit more, but it is still typically 30% or more less than it was before. A quick voltage check around the transmitter side showed all devices seemingly operating normally, although all were a bit lower than those listed in the spreadsheet on this site. That is because the main board is powered through a regulator and typically is less than 12v.
A curious observation is that the power loss is greatest on 20m, where before I had 9-12w out depending on the voltage of the source, and now it is down to 3-4w. 40 and 80 dropped from 14-15w before to 10-12 now and 10 from 3.25 to 1.5. I would have assumed an equal power drop from some common drive problem, so something else must be going on somewhere, although if I didn't have the old readings handy I would have probably thought this all looked normal.
=Vic=
|
Re: It'll never happen to me!
Vic, put a .1uf cap in parallel with C81 and see what happens. Barry
Did the antenna change?
_._
Well, Raj, I just did that. I checked the Hfe of a 2N3904 with leads and it registered at 423, while the "3904"? SMD devices only read? 280, about the same as a 2N2222A, so I suspect this is another case of a supplier somewhere picking up any NPN and saying, sure, it is whatever you ordered! So I swapped the device with leads for the SMD and brought up the power a bit more, but it is still typically 30% or more less than it was before. A quick voltage check around the transmitter side showed all devices seemingly operating normally, although all were a bit lower than those listed in the spreadsheet on this site. That is because the main board is powered through a regulator and typically is less than 12v.
?A curious observation is that the power loss is greatest on 20m, where before I had 9-12w out depending on the voltage of the source, and now it is down to 3-4w. 40 and 80 dropped from 14-15w before to 10-12 now and 10? from 3.25 to 1.5. I would have assumed an equal power drop from some common drive problem, so something else must be going on somewhere, although if I didn't have the old readings handy I would have probably thought this all looked normal.
=Vic=
|
Re: It'll never happen to me!
Did the antenna change?
_._
Well, Raj, I just did that. I checked the Hfe of a 2N3904 with leads and it registered at 423, while the "3904"? SMD devices only read? 280, about the same as a 2N2222A, so I suspect this is another case of a supplier somewhere picking up any NPN and saying, sure, it is whatever you ordered! So I swapped the device with leads for the SMD and brought up the power a bit more, but it is still typically 30% or more less than it was before. A quick voltage check around the transmitter side showed all devices seemingly operating normally, although all were a bit lower than those listed in the spreadsheet on this site. That is because the main board is powered through a regulator and typically is less than 12v.
?A curious observation is that the power loss is greatest on 20m, where before I had 9-12w out depending on the voltage of the source, and now it is down to 3-4w. 40 and 80 dropped from 14-15w before to 10-12 now and 10? from 3.25 to 1.5. I would have assumed an equal power drop from some common drive problem, so something else must be going on somewhere, although if I didn't have the old readings handy I would have probably thought this all looked normal.
=Vic=
|
Re: Question re transceiver kit UBITX v6
Al, I am 82 and I started in 1962 but kept up as I am a retired
professor with the subjects in Electronic Technology, Computer
Technology, Electronic Media Communications. You can service it.
There is only 12 volts and not the 400 and 600 volts or more with
tubes. Trace the 12 volts and 5 volts just as if you were tracing
the 400 volt line but without the shocks. You can not make it
worse so give it a try. We are all here to help.
73's
Thanks
Bob ,K1WYC
On 6/18/21 11:21 AM, alhill0728 via
groups.io wrote:
Thank you all for your
replies.
Unfortunately, I obtained my licence (VE3DLG) in 1963.? The
test was entirely on vacuum tubes.? I have not kept up with
solid state technology and at 83 years of age, I am unable to
do any trouble shooting of this magnitude.? I thank you again
for your advice ... I will try to get a new board.??
Al Hill, VE3DLG, Picton, Ontario.
-----Original Message-----
From: Curt via groups.io
<wb8yyy@...>
To: [email protected]
Sent: Tue, Jun 15, 2021 6:27 pm
Subject: Re: [BITX20] Question re transceiver kit UBITX v6
Let's troubleshoot and maybe its something simple.
You transition seems to have been from off to receive
when this occurred. Trace the path from 12 volt input
to the big 5 volt regulator. It could even be the on
switch that failed, or a wire fragment could have
created a short circuit, taking out the fuse. I would
check the path first with no dc input, with an
ohmmeter before connecting it to voltage. Sorry for
the extra adventure, and I am hopeful its something
simple with little damage. Do engage Evan as you
follow his deeper instructions.?
Curt
--
Connecting the classroom to the world via technology ??
|
Re: It'll never happen to me!
Well, Raj, I just did that. I checked the Hfe of a 2N3904 with leads and it registered at 423, while the "3904"? SMD devices only read? 280, about the same as a 2N2222A, so I suspect this is another case of a supplier somewhere picking up any NPN and saying, sure, it is whatever you ordered! So I swapped the device with leads for the SMD and brought up the power a bit more, but it is still typically 30% or more less than it was before. A quick voltage check around the transmitter side showed all devices seemingly operating normally, although all were a bit lower than those listed in the spreadsheet on this site. That is because the main board is powered through a regulator and typically is less than 12v.
?A curious observation is that the power loss is greatest on 20m, where before I had 9-12w out depending on the voltage of the source, and now it is down to 3-4w. 40 and 80 dropped from 14-15w before to 10-12 now and 10? from 3.25 to 1.5. I would have assumed an equal power drop from some common drive problem, so something else must be going on somewhere, although if I didn't have the old readings handy I would have probably thought this all looked normal.
=Vic=
|
Re: Question re transceiver kit UBITX v6
Thank you all for your replies.
Unfortunately, I obtained my licence (VE3DLG) in 1963.? The test was entirely on vacuum tubes.? I have not kept up with solid state technology and at 83 years of age, I am unable to do any trouble shooting of this magnitude.? I thank you again for your advice ... I will try to get a new board.??
Al Hill, VE3DLG, Picton, Ontario.
-----Original Message-----
From: Curt via groups.io <wb8yyy@...>
To: [email protected]
Sent: Tue, Jun 15, 2021 6:27 pm
Subject: Re: [BITX20] Question re transceiver kit UBITX v6
Let's troubleshoot and maybe its something simple. You transition seems to have been from off to receive when this occurred. Trace the path from 12 volt input to the big 5 volt regulator. It could even be the on switch that failed, or a wire fragment could have created a short circuit, taking out the fuse. I would check the path first with no dc input, with an ohmmeter before connecting it to voltage. Sorry for the extra adventure, and I am hopeful its something simple with little damage. Do engage Evan as you follow his deeper instructions.?
Curt
|
Re: uBitx as IF rig for transverter
Look at the pot after Q90. It allow to set output to almost zere.
|
Re: #ubitxv6-help Adding the W2AEW AGC to the uBitx v6
#ubitxv6-help
Jerry, thanks again for your input. The project went over my head so I decided to choose the easier path and ordered an AGC board from kit-projects.com:  The installation was quite easy and everything worked out of the box. Furthermore, I cannibalized a dead FT-290 and transplanted its S-meter to the uBitx:   I am very pleased with the result! Kind regards Michael
|
Re: It'll never happen to me!
What I would try Vic is remove the SMD and put back a leaded one and see. If the power comes back up then
the SMD ones must be fake. All depends from where you got them!
Raj
toggle quoted message
Show quoted text
At 18/06/2021, you wrote: Thanks, Evan, I'll be looking there. The drop in power occurs with both CW and steady tones on SSB on all bands compared to previous records I had when trying to figure why 40m CW was oddly low. I'll see if I can compare the gain of the SMD transistor to one with leads I have on hand, and then do some voltage checks, I guess. Still odd to me is that R82 was found loose and rattling around in the rig when I went to check Q90 when this first happened, and I wonder if it had ever been really soldered down.
=VIc=
|
Re: It'll never happen to me!
Thanks, Evan, I'll be looking there. The drop in power occurs with both CW and steady tones on SSB on all bands compared to previous records I had when trying to figure why 40m CW was oddly low. I'll see if I can compare the gain of the SMD transistor to one with leads I have on hand, and then do some voltage checks, I guess. Still odd to me is that R82 was found loose and rattling around in the rig when I went to check Q90 when this first happened, and I wonder if it had ever been really soldered down.
=VIc=
|
   For sale.
?Bitx V3 Ser No. ¡É0219/4 . Unassembled as purchased in original shipment case.? Audio chip is not the problematic WX brand TDA2822.? Included are the assembled but not installed K5BCQ kits for the ND6T AGC and VA7AT T/R Click Fix. ?See photos. ?Also included are five Axicom relays. Replacing the original relays with the Axicom relays reduces spurious emissions.? See various posts on this subject.? Asking $85.00 plus $15.50 USPS Priority mail shipping. ??
|
Re: It'll never happen to me!
Hi Vic,
I would check that C81, R83, and the traces around them did not get damaged.? The RC combination is used to boost the gain at higher frequencies.
Also, can you confirm that you made the power measurements with both CW and a solid tone on SSB?
Good hunting for the issue!
73
Evan
AC9TU
|
Re: It'll never happen to me!
Although I had leaded components for the Q90 3904 transistor and R82 100 ohm resistor that both failed, I waited to get some SMD devices thinking they might be easier to install, and not very expensive even when you have to get 100 of them. The repair was made and transmission resumes, and I had a nice quick chat with a midwest station on 20m to confirm it was working. However, before when I ran either CW or SSB I could see 12w on 20m into a dummy load when on a 13.8v power supply. Now, only 2 watts! I checked final bias and it is (and was) set correctly, and unfortunately RV1 is (and was ) at maximum output. The device I replaced Q90 with was an MMBT3904, which I thought was the SMD equal to a 2N3904, but it seems to have a boatload of less gain, or am I missing something here?
=Vic=
|
Vic WA4THR
Rafael Pinto [PU1OWL]
Raj vu2zap
Michael DK1MI/N1BSD