When diodes such as PIN diodes are placed in series, the signal isolation
improves in the off state but makes little difference in on state signal loss.
Gary
> On Dec 30, 2018, at 1:50 PM, wes Bolin <k5apl41@gmail.com> wrote:
>
> 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:
>
>> 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
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>> 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. 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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