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26 decembrie 2014

Hytera PD-785G, scurta prezentare

In ultima saptamana am avut ocazia de a testa o statie portabila Hytera PD-785G, varf de lance in gama de statii portabile a firmei chineze.
Sunt destul de reticent cand vine vorba de statiile produse de chinezi insa Hytera se dovedeste a fi o firma cu planuri ambitioase ce a cumparat divizia de radiocomunicatii profesionale de la celebra Rhode & Schwartz, demonstrand ca doreste sa devina un jucator serios in piata DMR si TETRA.

 Ca aspect, PD-785G are un design modern, apropiat de terminalele portabile Tetra; carcasa este realizata din policarbonat, in doua nuante de gri.

Ecranul este generos, color, afisand informatiile necesare utilizatorului, inclusiv nivelul de semnal si starea bateriei precum si sincronizarea cu satelitii GPS - pentru versiunea "G".

Incarcatorul este de tip "drop in", operarea fiind simpla si intuitiva.

Spre deosebire de Motorola, a carei gama "Intellicharge" furnizeaza informatii extinse despre acumulator, acesta este simplu, indicatia incarcarii realizandu-se cu un LED bicolor.



Antena este amplasata in mijlocul partii superioare, intre butonul de volum si comutatorul de canale.

Din acest motiv, aspectul este usor diferit de cel cu care suntem obisnuiti sa il intalnim la statiile portabile, accentuand aspectul particular al PD-785G.
Antena se conecteaza la statie printr-un conector tip SMA-Reverse, ceea ce inseamna ca vom avea nevoie de un adaptor SMA-mama <> SMA-mama pentru a conecta o antena externa.
Tot in partea de sus se gaseste si un buton orange, de regula utilizat pentru anuntarea unei urgente si punerea statiei in mod automat de funtionare.
Spre deosebire de competitorul direct, Motorola, selectorul de canale are doar 16 pozitii. Desi poate parea vetust, numerotarea canalelor poate fi de ajutor atunci cand dorim sa verificam canalul pe care este statia fara sa o mai scoatem de la centura. O singura privire la selector ne informeaza pe deplin.
Tot in partea superioara se afla un LED care ofera indicatii cu privire la traficul radio in frecventa selectata.


Chiar deasupra ecranului este o mica perforatie pentru microfon; prima reactie a unui amic radioamator a fost sa intrebe daca acolo este difuzorul si daca statia poate fi utilizata ca un telefon mobil ori ca o statie Tetra.

Difuzorul se afla in spatele tastaturii numerice, chiar sub tastele de meniu si, desi deschizatura pare insuficienta, cutia de rezonanta astfel realizata asigura claritate si volum suficient chiar si pentru utilizarea in medii zgomotoase cum este, de exemplu, utilizarea in mobil.

 Tastele sunt din cauciuc si nu din plastic cauciucat cum intalnim la majoritatea statiilor chinezesti, si furnizeaza un feedback tactil clar dar discret.

Tastatura este retroiluminata insa, pentru conservarea energiei, retroiluminarea este activa in mod curent doar la ecran; numai la accesarea meniului se aprind si LED-urile de sub tastatura numerica.

In laterala stanga se afla tasta PTT si doua taste programabile. Prin intermediul soft-ului de programare se pot aloca diverse functii acestor doua taste, cum ar fi: modificarea puterii de emisie, scanare, modificarea treptelor de squelch samd.

Tasta PTT este inconjurata de o garnitura orange si este amplasata intr-o protuberanta de protectie.

Tot pe latura stanga, in partea inferioara se afla o eticheta cu modelul statiei.



Pe latura din dreapta se gaseste conectorul de accesorii. Acesta este acoperit de un capac de protectie, realizat din cauciuc. Spre deosebire de alte statii profesionale, la Hytera PD-785, capacul este fixat de corpul statiei printr-o balama.

Personal, consider ca aceasta solutie este mult mai buna comparativ cu fixarea printr-o "codita" cauciucata care, mai devreme sau mai tarziu se va rupe si va duce la pierderea protectiei.

Pentru siguranta, capacul de protectie se imobilizeaza in pozitia "inchis" cu ajutorul unui surub cu profil redus.



 Hytera PD-785 poate fi echipata cu un suport de fixare la curea, care se monteaza direct pe corpul statiei, pe o decupare de aluminiu. Gasesc foarte inspirata alegerea, spre deosebire de solutia Motorola, care a decis sa amplaseze clips-ul de curea pe spatele bateriei!
Un plus, neesential pentru functionarea statiei dar pentru precizia prelucrarii, este faptul ca nu exista niciun joc mecanic intre statiei si baterie!
Bateria cu care vine echipata statia este LiIon, 7,4V / 2000mAh, existand posibilitatea echiparii cu o baterie extinsa, de 2500mAh.
Durata de exploatare a bateriei este superioara statiei Motorola DP4801 cu care am facut unele comparatii in utilizare. Spre deosebire de Motorola, Hytera PD-785 poate fi utilizata doua zile pe bateria standard si circa 3 zile cu cea extinsa, in utilizare moderata, mixt analogic si digital.

Desi statia este, in principiu, programabila cu ajutorul calculatorului, exista posibilitatea de a programa o serie de parametri utili direct din tastatura, cu conditia activarii acestei optiuni in softul de programare. Putem programa frecventa canalului radio, ID-uri ale corespondentilor dar nu si CTCSS.

In "lumea reala", statia se prezinta bine, fiind suficient de sensibila si avand o buna procesare a semnalului inclusiv pe calea analogica.
Desi sunt unele voci care critica antena cu care statia vine echipata, personal nu am nimic de reprosat acesteia. E foarte posibil ca utilizatorii nemultumiti sa nu fi selectat gama de frecvente corecta.
Cum spuneam si mai sus, prezenta unui conector de antena este un plus pentru cei care doresc sa utilizeze statia si in mobil. Pentru ei, exista un suport auto care permite incarcarea bateriei pe durata utilizarii statiei.
Rapoartele de receptie sunt incurajatoare si nu releva nimic suspect; neanuntati, corespondentii nu au remarcat diferente intre Motorola si Hytera PD-785G.

Per ansamblu, statia este o alternativa pertinenta la rivala mult mai scumpa de la Motorola, DP-4801. Este o statie robusta, de calitate, receptia si emisia rivalizand cu orice alt competitor din gama de varf; politica de vanzare cu pret preferential catre radioamatori a dus la proliferarea Hytera PD-785G in randul utilizatorilor retelei MARC-DMR.
Pentru cei care au restrictii la bugetul destinat echipamentelor HAM, statia se prezinta si in versiunea fara GPS (PD-785), pretul ajungand astfel la aproximativ 60% din cel al unei statii Motorola DP-4801.

Chiar daca nu este "Statia", Hytera PD-785G este o alternativa serioasa, in opinia mea fiind varful in clasa de statii DMR de buget redus.

73 de Adrian, YO3HJV

Completare (26 august 2015)

Prin update FW, s-au rezolvat o serie de probleme, in special legate de FPP. Acum se poate programa si CTCSS, distinct pe Rx fata de Tx!
De asemeni, o facilitate pe care nu am gasit-o la Motorola este "Pseudo Trunk", care poate fi activata via FPP si care permite ascultarea simultana a TG-urilor active pe AMBELE TIMESLOT in frecventa respectiva! E ca si cum statia ar scana canale cu TS diferit, facilitate extrem de utila pentru monitorizarea TG internationale si a celor locale.






25 decembrie 2014

Hytera PD-785G review


My DMR radio collection y has grown by adding two Hytera radios; one is the flagship PD-785G and the second one is the small PD-365.

I was very reticent about chinese radios but the recently increase in the number of users of Hytera on MARC-DMR network made me raise the elbow and I promised myself that I will not miss the chance to test one.
 


We’ll review the first one for the start.


 Look and feel

Front

PD-785G is a little smaller than the direct competitor, Motorola DP-4801 and look more like a Tetra terminal than like a conventional radio.
With the central mounted antenna, the radio looks somehow unfamiliar and Hytera pretend that this design help improve the RF performance. Well, I read somewhere that the antenna is not so good but after a week of testing I admit that is not better than a longer antenna but at it’s dimensions is not worst than the 9 cm one from Motorola.

On the front pannel we have a big colour LCD and above it is a little hole for the microphone. First reaction of a fellor ham was to put the radio to the ear as the microphone looks pretty like the earphone of a mobile phone.

Right under the screen are the menu keys and a big directional key, only for up and down (at DP-4801, there are also Left-Right on the same key). Under that, we have the numeric keypad.
What is particular to this model is that the speaker is UNDER the numeric keyboard; a long slit is between the menu and numeric keys and there is the speaker. 




Left side

On the left side are the PTT and two programmable keys.
The PTT has a nice orange gasket around and feel a little fragile. The two programmable butons feel ferm and cannot be pressed by accident; they need some determination to have them pushed.
In the CPS you can program them with a lot of functions, one for quick press and one for long press but I found that the combination is available only for certain functions not for any of them and once programmed, there are some bugs that make that button not functional. Maybe is just a firmware problem but tend to be annoying!
Under the buttons is a little plastic plate which identify the model. Mine is a “G” one, with GPS.

Right side

 
On the right side of the Hytera PD-785G we find an accessory connector. This one is half of the Motorola’s and the cover is hinged so, goodby loosing it! Of course, if you are determined, you can break the hinge and throw away the cover!

 There are some sort of grip helpers on the side of the radios but despite the look, they are made by the same plastic as the whole case and not of rubber as one may expect from the look.

 
  
Upper side

 
On the top of the radio we have the two knobs, VOL/ON-OFF and the Channel selector. The channel selector is an interesting thing; it has 16 positions. This might look a little obsolete but I do find it usefull especially when the radio is on the belt. You can find the channel with a glimpse at the channel knob.
Also on the top, just near the channel selector is an orange button for emergencies. This one can be programmed as the other ones, with the same observations…
In the right side, near the Vol/On-Off is the status LED; a little protuberance make it visible even if you look to the radio directly from the front side.
The antenna is between the knobs, as I said before, givind an unusual look to the radio.
The antenna connector is a reverse SMA. The reverse SMA connector is a nice touch and permit us, the hams, to put a better antenna or even to connect a mobile antenna to this radio for a better coverage.
 


Back

 

The battery attach not by sliding and there is no gap between the battery and the radio! Once attached, there is no jolt or lost motion between them (shame Motorola!).
The belt clip is attached to the radio and not to the battery. On the radio is a metal plate and the belt clips attached with two M4 screws in the old way. I like this, it’s very solid!






Battery

The stock battery is a 7.4V/2000mAh and the battery life is better than the Motorola’s. With the stock battery at a moderate use, on analog channels and digital channels, the radio can be used for two days with no problems. With an optional 2800MAh battery I used it for about 3 and a half days.


 



I will not enter in the subtilities of programming the radio, this is a little complicate and depends on what do you want to do with the radio so I will emphasize some of the bugs or the features of the radio.
Bug:  The audio amplifier is not balanced and is powered on receiving. This express with a loud “bop” even at low volumes when the radio start to receive traffic.  Motorola has a balanced AF amplifier…
Feature:  When rotate the knob or press any key  (but not the Menu key or the numeric keys), only the LCD fire up. The backlight of the numeric keys stays off. This can save some  battery!
Bug: The radio cannot scan digital and analog channels at the same time. You can scan channels on the same kind only. Motorola can scan combined lists.
Feature: When receiving, the radio starts the LCD backlight. Very usefull to see what’s happening on the digital channels.

On the traffic, the radio is sensitive and the quality of audio is very good on both analog and digital. I see no differences on digital  when compared with Motorola with the latest firmware (2.4.x).
The audio reports on modulation were good and, during the tests I found that the scrambler is higly compatible with Motorola’s. Understandable because is a simple inversion…

The radio is not a bad one but is not “The radio”. Some bugs can be solved via firmware upgrade but others are “hardware defined” and need redesign. The GPS has a nice feature by wich the user can send as a short message the position.

The missing Bluetooth can be a shortage as I programm my DP-4801 via Bluetooth (the Motorola programming cable is too expensive!) but the Hytera cable is affordable at a half of the Motorola’s price so the absence of BT  is not a real problem for me.

If the price is a key component in the buying decision, the Hytera PD-785G can be the best choice as the price/quality is unbeatable.

It is compatible with the MARC-DMR network except the short messages but the latest firmware updates for Motorola radios and repeaters which let the user choose between Motorola proprietary and DMR standard open the door for full compatibility between Hytera and Motorola networks.

The quality of the hardware is much better than other Chinese radios and i expect to be better and better after Hytera bought  Rhode & Schwartz Professional Mobile Radio division
The policy to sell radios for hams at a low price is a good impulse for us to explore the future of the telecommunications.

I will not trade the DP-4801 for a Hytera PD-785G but I certainly use this radio day by day!
73 de Adrian YO3HJV

12 decembrie 2014

Home made IF Filter

Today I started wondering what should I do with some quartz cristal that I have around...
A IF filter was my first thought and I started to fool around with them.
First, I cut a small piece of PCB and prepared for "dead-bug" soldering style.
I prepared also two small piece of RG58U to connect the filter to a Marconi IFR analyzer.
In my box I had two type of cristals.
One type is a 4 MHz and the second one is a 38.9 MHz, both of them HC-49U format.
First I started with the 4 MHz ones but I didn't noticed a nice shape on the analyzer so I quicly moved around to 38.9 ones.
These are overtone cristals so I watched to fundamental frequency which had to be around 12.6 MHz.
And it was!

I don't want to bother you with math stuff. Instead, I will put the self-explanatory pictures.

The two SMD resistors are 470 Ohms and the small SMD capacitors are 1nF.


Here it is the filter on the tests. After tests, it can be put on a smaller and nicer board. I didn't had capacitors, I will play with them monday, HI.
 There are 9 cristals. At less than 1 USD, I believe is a good alternative!
Indeed, one had to choose from a big bunch, but I had an already opened bag of cristals with around 25 pcs. I observed on the analyzer that there was two type of shape for that bunch.

The insertion loss is around -4db wich is not bad at all!
 The center frequency was set at 12.96400 MHz. This might be somehow unusual for elder hams but with modern DSS it's easy to set the IF to this value.



 -22db attenuation at +1.5 kHz

 -27 db attenuation at - 1.5 kHz


 It has a passband of around 1.8 kHz at -15 db. Maybe I will send it to some experimenter who want to play with because I am very curious about how it sound in the real HF traffic!


Other pictures:






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