Hi Gary
Sorry, I was using ambiguous description of the problem location. I am
referring to the Bandpass Filter Board 81409 that includes RF
Preamplification.
I understand that dodes in series increase PIV protection, but see no need
for this in the low level receive line ........That's one thing I'm curious
about. Other thing
is the transistor function.....it sure did attenuate the signals with a B
to C short circuit.....it got hot too. Why did it not get documented
anywhere?
The transistor might have been added by the factory since the base lead is
going through a hole drilled in the circuit board, while the Emitter and
Collector were soldered
onto component leads above the board.
I am going to put a new transistor back in the radio and see what happens.
Thanks for your comments,
Wes
On Sun, Dec 30, 2018 at 11:00 AM <tentec-request@contesting.com> wrote:
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> Today's Topics:
>
> 1. Re: TenTec Digest, Vol 192, Issue 25 (wes Bolin)
> 2. Re: TenTec Digest, Vol 192, Issue 25 (MadScientist)
> 3. Re: Omni VI+: low TX and RX on 12 meters (Phil Erickson)
> 4. Re: TenTec] Omni VI+: low TX and RX on 12 meters (Peter Bertini)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 29 Dec 2018 13:03:32 -0600
> From: wes Bolin <k5apl41@gmail.com>
> To: tentec@contesting.com
> Subject: Re: [TenTec] TenTec Digest, Vol 192, Issue 25
> Message-ID:
> <
> CALM7jM6_OjGwUxDp0xegHfabzHnXM4QUQ_sK4cQ+zomuq+Oy8g@mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Halleluyah I found the problem!
>
> The circuitry is still a puzzle to me so hopefully someone can shed some
> light on it:
>
> The Diode D10 on the Front End Board is actually two small diodes in series
> in my radio. The junction of the two individual diodes the Collector of a
> MPS6514 NPN transistor soldered to it. The
> transistor Emitter is soldered to the Jumper near C65, C66, and Base is
> soldered into a hole on the circuit board. The transistor is not in any
> documentation that I can find and the need to double up the diodes is not
> documented either. The transistor was getting hot to my touch, so
> Unsoldered the Emitter and still hot, so unsoldered the Collector. This
> allowed the signal path to not be attenuated any longer and the radio's
> sensitivity is back to normal.
>
> Questions:
> 1. Why double dodes?
> 2. Why the transistor?
> 3. Do I need to replace the transistor or leave it out of the circuit?
>
> All receive signals go through D10, so it was where the Receive signal was
> being attenuated.
> Wes
>
> On Sat, Dec 29, 2018 at 11:00 AM <tentec-request@contesting.com> wrote:
>
> > Send TenTec mailing list submissions to
> > tentec@contesting.com
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> > http://lists.contesting.com/mailman/listinfo/tentec
> > or, via email, send a message with subject or body 'help' to
> > tentec-request@contesting.com
> >
> > You can reach the person managing the list at
> > tentec-owner@contesting.com
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of TenTec digest..."
> >
> >
> > Today's Topics:
> >
> > 1. OMNI V Failed (wes Bolin)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Fri, 28 Dec 2018 15:41:39 -0600
> > From: wes Bolin <k5apl41@gmail.com>
> > To: tentec@contesting.com
> > Subject: [TenTec] OMNI V Failed
> > Message-ID:
> > <CALM7jM50KHwghA8gtYw5o36rrm6q+1iddJcJngNygL8GM5-=
> > rA@mail.gmail.com>
> > Content-Type: text/plain; charset="UTF-8"
> >
> > Worked OK, turned it off. Next day it turned on but no Receive. It
> > belongs to my friend so I brought it home to troubleshoot. What I know
> is:
> > 1. It was intermittently working when it was turned on--sometimes the
> > display did not light up, other LEDs were On randomly....I found that the
> > N4PY chip was probably the problem after reading the book. I put the
> > original chip back in and it turns On nicely. good display, etc. (A
> > replacement N4PY chip is coming).
> > 2. The radio transmits OK; power out and SSB all seem good
> > 3. I tested the TRX-RX switch with Ohmmeter and it is switching OK
> > 4. In RX Ant I get much stronger signal through the radio than in the
> TRX
> > Ant
> > connector on Receive. On 14MHz the signal drops into the noise at about
> 20
> > microvolts in the RX input. Even with S-meter well over S-9 (+30) with
> the
> > RX
> > input, I can hear it S1 or so through the TRX input.
> >
> > So the receiver is pretty deaf with the RX input and unusable with the
> TRX
> > input.
> >
> > 5. The Attenuator works with the receive signals
> > 6. I have tried 80M and 20M so its not band dependent
> > 7. Measured voltages and they are correct
> > I suspect that my friend turned the radio Off and On by leaving the OMNI
> V
> > "On" and switching the Power Supply (Book says don't do this). I'm
> > guessing a transient took out the microprocessor, and caused the RX
> > problem.
> >
> > Any help or ideas will be greatly appreciated.
> > 73
> > Wes
> >
> >
> > ------------------------------
> >
> > Subject: Digest Footer
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
> >
> > ------------------------------
> >
> > End of TenTec Digest, Vol 192, Issue 25
> > ***************************************
> >
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 29 Dec 2018 13:35:23 -0600
> From: MadScientist <dukeshifi@comcast.net>
> To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
> Subject: Re: [TenTec] TenTec Digest, Vol 192, Issue 25
> Message-ID: <744004E7-249F-4BB1-B0CC-296FAB04D24A@comcast.net>
> Content-Type: text/plain; charset=us-ascii
>
> The use of dual diodes is likely an attempt to improve isolation at this
> point and also to allow use of that transistor to pull the signal point to
> ground, thereby improving attenuation here.
>
> Are you talking the band pass tuning board or RF front end? The manual
> list no such board named RF front end.
>
> Gary
>
> > On Dec 29, 2018, at 1:03 PM, wes Bolin <k5apl41@gmail.com> wrote:
> >
> > Halleluyah I found the problem!
> >
> > The circuitry is still a puzzle to me so hopefully someone can shed some
> > light on it:
> >
> > The Diode D10 on the Front End Board is actually two small diodes in
> series
> > in my radio. The junction of the two individual diodes the Collector of
> a
> > MPS6514 NPN transistor soldered to it. The
> > transistor Emitter is soldered to the Jumper near C65, C66, and Base is
> > soldered into a hole on the circuit board. The transistor is not in any
> > documentation that I can find and the need to double up the diodes is not
> > documented either. The transistor was getting hot to my touch, so
> > Unsoldered the Emitter and still hot, so unsoldered the Collector. This
> > allowed the signal path to not be attenuated any longer and the radio's
> > sensitivity is back to normal.
> >
> > Questions:
> > 1. Why double dodes?
> > 2. Why the transistor?
> > 3. Do I need to replace the transistor or leave it out of the circuit?
> >
> > All receive signals go through D10, so it was where the Receive signal
> was
> > being attenuated.
> > Wes
> >
> > On Sat, Dec 29, 2018 at 11:00 AM <tentec-request@contesting.com> wrote:
> >
> >> Send TenTec mailing list submissions to
> >> tentec@contesting.com
> >>
> >> To subscribe or unsubscribe via the World Wide Web, visit
> >> http://lists.contesting.com/mailman/listinfo/tentec
> >> or, via email, send a message with subject or body 'help' to
> >> tentec-request@contesting.com
> >>
> >> You can reach the person managing the list at
> >> tentec-owner@contesting.com
> >>
> >> When replying, please edit your Subject line so it is more specific
> >> than "Re: Contents of TenTec digest..."
> >>
> >>
> >> Today's Topics:
> >>
> >> 1. OMNI V Failed (wes Bolin)
> >>
> >>
> >> ----------------------------------------------------------------------
> >>
> >> Message: 1
> >> Date: Fri, 28 Dec 2018 15:41:39 -0600
> >> From: wes Bolin <k5apl41@gmail.com>
> >> To: tentec@contesting.com
> >> Subject: [TenTec] OMNI V Failed
> >> Message-ID:
> >> <CALM7jM50KHwghA8gtYw5o36rrm6q+1iddJcJngNygL8GM5-=
> >> rA@mail.gmail.com>
> >> Content-Type: text/plain; charset="UTF-8"
> >>
> >> Worked OK, turned it off. Next day it turned on but no Receive. It
> >> belongs to my friend so I brought it home to troubleshoot. What I know
> is:
> >> 1. It was intermittently working when it was turned on--sometimes the
> >> display did not light up, other LEDs were On randomly....I found that
> the
> >> N4PY chip was probably the problem after reading the book. I put the
> >> original chip back in and it turns On nicely. good display, etc. (A
> >> replacement N4PY chip is coming).
> >> 2. The radio transmits OK; power out and SSB all seem good
> >> 3. I tested the TRX-RX switch with Ohmmeter and it is switching OK
> >> 4. In RX Ant I get much stronger signal through the radio than in the
> TRX
> >> Ant
> >> connector on Receive. On 14MHz the signal drops into the noise at
> about 20
> >> microvolts in the RX input. Even with S-meter well over S-9 (+30) with
> the
> >> RX
> >> input, I can hear it S1 or so through the TRX input.
> >>
> >> So the receiver is pretty deaf with the RX input and unusable with the
> TRX
> >> input.
> >>
> >> 5. The Attenuator works with the receive signals
> >> 6. I have tried 80M and 20M so its not band dependent
> >> 7. Measured voltages and they are correct
> >> I suspect that my friend turned the radio Off and On by leaving the
> OMNI V
> >> "On" and switching the Power Supply (Book says don't do this). I'm
> >> guessing a transient took out the microprocessor, and caused the RX
> >> problem.
> >>
> >> Any help or ideas will be greatly appreciated.
> >> 73
> >> Wes
> >>
> >>
> >> ------------------------------
> >>
> >> Subject: Digest Footer
> >>
> >> _______________________________________________
> >> TenTec mailing list
> >> TenTec@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/tentec
> >>
> >>
> >> ------------------------------
> >>
> >> End of TenTec Digest, Vol 192, Issue 25
> >> ***************************************
> >>
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 29 Dec 2018 15:40:57 -0500
> From: Phil Erickson <phil.erickson@gmail.com>
> To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
> Subject: Re: [TenTec] Omni VI+: low TX and RX on 12 meters
> Message-ID:
> <CAAZaqEtU6h3uoiFP=
> FEgTpXN8uDOzj5f3LzGSh4YrQVJLAyHBA@mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi all,
>
> More investigation has narrowed the problem to the BPF/front end board
> 81593. We'll use 15 and 10 meters as our "working normally" and 12 meters
> as "working abnormally" for this discussion:
>
> - LO input from the XO-LO board at connector 26 is at exactly the right
> appropriate frequency for a 9 MHz IF, and nearly constant voltage for
> 15/12/10 meters. That eliminates the XO-LO board as the problem (relief!).
> - TX input at connector 27 is also nearly identical on 15/12/10 meters.
> - However, the output at connector 24, which goes off to the low level
> driver board, is not the same for all three.
>
> Using a 1 Mohm input impedance on a Tek 2465A scope:
>
> 15, 10 meters: in TUNE mode, signal increases with PWR knob up to
> about +/- 2V at three dots up from minimum (10:30 am clock position) and
> then essentially saturates
> 12 meters: in TUNE mode, signal increases with PWR knob but only up to
> about +/- 0.12V at three dots up from minimum and then essentially
> saturates
>
> Not sure why the signal is saturating at the 10:30 am position as I would
> have figured it would go up as I turned PWR up further. (It does go up to
> a clean 90 watts or so on 15 and 12 meters when everything is hooked back
> together.) No matter; the problem is clearly in low output at 12 meters
> from 81593.
>
> Since 81593 has individual BPFs for each band that are used for both TX
> and RX, my guess is that the BPF is off frequency for 12 meters which would
> explain why I have a relatively deaf receiver by 20 dB on that band as well
> as low TX output.
>
> Now the next question to this group: does anyone have the alignment
> procedure for a 81593 BPF/front end board? The manual does not describe
> one. I am also very careful about adjusting slugs as like many of you,
> I've had inductor cores snap in two with too much pressure, so I want to do
> the minimal amount of tweaking to fix the problem and not do too much
> "golden screwdriver" wiggling back and forth. Knowing what to inject and
> where to inject it would be great. (I have HP signal generators and the
> like available.)
>
> This list is really terrific - and thanks to Gary W0DVN and Pete in
> particular!
>
> 73
> Phil W1PJE
>
>
> ------------------------------
>
> Message: 4
> Date: Sun, 30 Dec 2018 10:33:25 -0500
> From: Peter Bertini <radioconnection@gmail.com>
> To: tentec@contesting.com
> Subject: Re: [TenTec] TenTec] Omni VI+: low TX and RX on 12 meters
> Message-ID:
> <
> CA+uDY2SARwO74o0z48Y4QpDCjPJjz6zfREqahQ5xVia2mej6pg@mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Phil
>
> Do NOT attempt to realign those passband filters! Normal aging will not
> give you a 20 dB signal loss. Alignment can mask other problems and can
> compound finding a resolution for your problem. Realignment would problem
> require a sweep generator, or at worst, hours of tedious stagger tuning
> while manually sweeping the response curves.
>
> A high Z scope is fine, since you are tracing 50 ohm signal paths it will
> not load the circuits.
>
> Getting back to your problem: do what Gary suggested. Carefully resolder
> all of the connections for the components in that particular filter. You
> might want to first verify that the associated switching diodes are indeed
> being forward biased when that band range is selected! It could be as
> simple as the diodes not being switched on.
>
> I had a similar passband filter failure in LO system. No fun.
>
> regards
>
> Peter k1zjh
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>
> ------------------------------
>
> End of TenTec Digest, Vol 192, Issue 26
> ***************************************
>
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