[App_rpt-users] Hamtronics receiver issue with AllStar RTCM

[Skyler F]

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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