[App_rpt-users] Hamtronics receiver issue with AllStar RTCM

Sat Apr 2 21:06:16 UTC 2016

"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 .03µ) , 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
>>>>
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>>>
>>>
>>>
>>> --
>>> Skyler Fennell
>>> amsatnet.info
>>> KDØWHB
>>> 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
>> KDØWHB
>> <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
> KDØWHB
> electricity440 at gmail.com
>
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