[App_rpt-users] Hamtronics receiver issue with AllStar RTCM (Chuck Henderson) Re: App_rpt-users Digest, Vol 86, Issue 5

Sun Apr 3 01:34:42 UTC 2016

Impedance matters.  That the output/source circuit and/or the input/load circuit mis-match alters frequency response is sloppy implementation.
Unless you have complete control over system components design and implementation, it is prudent for audio-take-off/recipients/input circuits to not terminate at whatever unknown source impedance, but instead bridge-tap at 10k ohms.

The outputs you have design/implementation control over can be whatever you want, but convention is typically 600 ohms, 0 dB max standard level from 300-3000 Hz.  

Squelch noise detection from an Rx detector may begin at 4 KHz (marginally low) or typically 6 KHz for white noise.    The Motorola Micor SQ chips and not so obvious app notes indicate/allow a higher frequency detection limit at the base/repeater (6KHz) than the mobile (more subject to flutter) of 4KHz.

All that yadda aside... folks need to learn that audio connections between unknown gear might best be bridging (10k ohms) to get audio, and should provide/tolerate 600 Ohms to give audio.  If even bridging affects the frequency response the source audio point is questionably engineered/implemented.
Impedance matters.

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Today's Topics:

  1. Re: Hamtronics receiver issue with AllStar RTCM (Chuck Henderson)
  2. How to add chan_rtpdir.c to DIAL (Michael J. Wolthuis)

----------------------------------------------------------------------

Message: 1
Date: Sat, 2 Apr 2016 16:06:16 -0500
From: Chuck Henderson <rpt2 at chuck.midlandsnetworking.com>
To: Skyler F <electricity440 at gmail.com>
Cc: "app_rpt-users at ohnosec.org" <app_rpt-users at ohnosec.org>
Subject: Re: [App_rpt-users] Hamtronics receiver issue with AllStar
    RTCM
Message-ID:
    <CADEYVwhCSq8vx+g58i8tZVHGM5P6CvKsAiq2QeHqPmXzefFLKw at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

"Once you have verified that the firmware is running, place a jumper shunt
on JP8 and JP10. Be sure to
do this at a reasonable human room temperature (like 60-80 deg. F). This is
necessary because this
procedure initializes the operating parameters in the EEPROM and also does
a *temperature compensation*
*diode calibration* which needs to happen at room temperature. Once the
jumper shunts
have been installed, power-cycle the board and wait for the system activity
light to come on steady
(about 4 seconds or so after the 5 second initial wait time). Then remove
the jumper shunts."

>From https://allstarlink.org/votersystem.pdf page 20
Chuck

On Sat, Apr 2, 2016 at 3:23 PM, Skyler F <electricity440 at gmail.com> wrote:

> Well stupid me for not listening to you guys. I guess the hamtronics is
> really sensitive to low impedance outputs, and the highs get cut off if you
> have any sort of load at all. When I turned on the internal amplifier, the
> RTCM was happy with calibrating squelch.
>
> Can anybody explain to me what "Diode calibration" means?
>
> 73,
> Skyler
>
> On Wed, Mar 30, 2016 at 5:42 PM, Joe Leikhim <rhyolite at leikhim.com> wrote:
>
>> Skyler;
>>
>> Here is a wideband VHF 136-156 MHz radio that will solve your ham club
>> problems for $35 each. If these were UHF I would be buying a bushel full.
>> You will need to get the programming software from Ritron. I think it is
>> free.
>>
>> There are similar models with an enclosure, but for much more $$.
>>
>> See the auction below on E-Bay:
>>
>> Seller dale575
>>
>> Ritron VHF Transceiver PCA, 136-156MHZ, 5 Watt, Model DTX-142-GCWD-I
>>
>>
>> http://www.ebay.com/itm/Ritron-VHF-Transceiver-PCA-136-156MHZ-5-Watt-Model-DTX-142-GCWD-I/191557457767?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D35389%26meid%3D4bbbffc700cc4aefba654c3ce0d394f8%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D401085025343
>>
>>
>>
>> On 3/30/2016 12:11 PM, Skyler F wrote:
>>
>> Factory tuned from the factory. And I don't even have a signal generator
>> / counter good for RF. We got one hamtronics board, and won't buy another
>> until we get this one working.
>>
>> On Wed, Mar 30, 2016 at 10:08 AM, Joe Leikhim <rhyolite at leikhim.com>
>> wrote:
>>
>>> Were these receivers factory built and tuned or did individual club
>>> members build them? Either way, you might try others from the lot. If you
>>> have only a rudimentary signal generator and / or frequency counter,
>>> perhaps I can walk you through some "field expedient" steps over the phone.
>>>
>>>
>>> On 3/30/2016 12:01 PM, Skyler F wrote:
>>>
>>> I don't have the test equipment to go through all of the dirty Local
>>> Oscilator, SINAD, etc., so I will have to wait on that a few weeks before
>>> the president of the club gets back in town.
>>>
>>> WHEN I bypassed the capacitor and resistor ( 1k and .03?) , the RTCM was
>>> able to calibrate squelch. The LED flashed several times and then was
>>> steady. Maybe the capacitor is the wrong value. There was no code on it,
>>> but based on the resistor code, the value was correct.
>>>
>>> 73
>>> Skyler
>>>
>>> On Mon, Mar 28, 2016 at 4:08 PM, Joe Leikhim < <rhyolite at leikhim.com>
>>> rhyolite at leikhim.com> wrote:
>>>
>>>> If you are using an external reference, you cannot make up for the 2nd
>>>> LO error if it is wildly off. There is an easy SINAD related test in
>>>> EIA-603 that is called Offset Acceptance Bandwidth that would indicate if
>>>> the IF were off center. Things that could go wrong apart from simple
>>>> misalignment of the Quad Detector coil could include the LO crystal being
>>>> way off frequency, the IF filters being wrong BW or off spec pass frequency.
>>>>
>>>> Given the symptoms, I am putting my money on a misadjusted quad coil.
>>>>
>>>> Joe
>>>>
>>>> On 3/28/2016 5:06 PM, Bryan Fields wrote:
>>>>
>>>>> On 3/28/16 2:51 PM, Joe Leikhim wrote:
>>>>>
>>>>>> 1) Make sure the receiver First Local Oscillator is adjusted correctly
>>>>>> on frequency. (Fo -10.700 MHz) Likewise the second LO should be at
>>>>>> around 10.2450 MHz. The second LO is not adjustable, so any minor
>>>>>> error
>>>>>> would have to be made up with the TCXO U3. After this second step:
>>>>>>
>>>>>> Then :
>>>>>>
>>>>>> 2) Make sure the general alignment is set properly, especially the
>>>>>> discriminator coil T2 which responds to 10.7000 MHz from a signal
>>>>>> generator, has an S curve response.  In my experience with these sort
>>>>>> of
>>>>>> Quadrature  Detector chips, you can get a false sense of IF centering
>>>>>> where the noise component is suppressed. You might try adjusting for
>>>>>> maximum noise first without the 10.7000 MHz signal. Be careful you
>>>>>> don't
>>>>>> jam the coil slug.
>>>>>>
>>>>> These are both very good points i didn't consider.  I normally don't
>>>>> check my
>>>>> reference oscillators in the hamtronics as they are using an external
>>>>> 10MHz
>>>>> source.
>>>>>
>>>>> You will want to check SINAD on it as well, if it's not making spec
>>>>> (and those
>>>>> hamtronics are very sensitive), something else is wrong with it.
>>>>>
>>>>>
>>>> --
>>>> Joe Leikhim
>>>>
>>>>
>>>> Leikhim and Associates
>>>>
>>>> Communications Consultants
>>>>
>>>> Oviedo, Florida
>>>>
>>>> JLeikhim at Leikhim.com
>>>>
>>>> 407-982-0446
>>>>
>>>> WWW.LEIKHIM.COM
>>>>
>>>> _______________________________________________
>>>> App_rpt-users mailing list
>>>> App_rpt-users at ohnosec.org
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>>>>
>>>> To unsubscribe from this list please visit
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>>>>
>>>
>>>
>>>
>>> --
>>> Skyler Fennell
>>> amsatnet.info
>>> KD?WHB
>>> electricity440 at gmail.com
>>>
>>>
>>> --
>>> Joe Leikhim
>>>
>>>
>>> Leikhim and Associates
>>>
>>> Communications Consultants
>>>
>>> Oviedo, Florida
>>> JLeikhim at Leikhim.com
>>> 407-982-0446
>>> WWW.LEIKHIM.COM
>>>
>>>
>>
>>
>> --
>> Skyler Fennell
>> amsatnet.info
>> KD?WHB
>> <electricity440 at gmail.com>electricity440 at gmail.com
>>
>>
>> --
>> Joe Leikhim
>>
>>
>> Leikhim and Associates
>>
>> Communications Consultants
>>
>> Oviedo, Florida
>> JLeikhim at Leikhim.com
>> 407-982-0446
>> WWW.LEIKHIM.COM
>>
>>
>
>
> --
> Skyler Fennell
> amsatnet.info
> KD?WHB
> electricity440 at gmail.com
>
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Message: 2
Date: Sat, 02 Apr 2016 21:07:42 -0400
From: "Michael J. Wolthuis" <wolthuis at gmail.com>
To: "app_rpt-users at ohnosec.org" <app_rpt-users at ohnosec.org>
Subject: [App_rpt-users] How to add chan_rtpdir.c to DIAL
Message-ID: <0426FF03-B422-471B-A684-7F9BF8307E2B at gmail.com>
Content-Type: text/plain; charset="utf-8"

I am finally replacing a very old install of ACID at a HUB site with DIAL.

This site does have some ties though to rtpDir_tm which is older, but still fun and working?

I can?t seem to get chan_rtpdir.c to compile into Asterisk.  I put it in the channels folder and recompiled, but it acts like it didn?t add it / compile it in.

[Apr  2 21:02:37] NOTICE[1305] app_rpt.c: Normal Repeater Init  2363    

[Apr  2 21:02:37] NOTICE[1305] app_rpt.c: Normal Repeater Init  1000    

[Apr  2 21:02:37] WARNING[1318] channel.c: No channel type registered for 'rtpdir'

[Apr  2 21:02:38] WARNING[1305] app_rpt.c: rpt_thread restarted on node 2363

[Apr  2 21:02:38] WARNING[1305] app_rpt.c: rpt_thread restarted on node 1000

[Apr  2 21:02:38] WARNING[1322] channel.c: No channel type registered for 'rtpdir'

[Apr  2 21:02:40] NOTICE[1305] app_rpt.c: RPT thread restarted on 2363

[Apr  2 21:02:40] WARNING[1305] app_rpt.c: rpt_thread restarted on node 2363

[Apr  2 21:02:40] NOTICE[1305] app_rpt.c: RPT thread restarted on 1000

[Apr  2 21:02:40] WARNING[1305] app_rpt.c: rpt_thread restarted on node 1000

Anyone have any suggestions?
Mike
kb8zgl

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