[App_rpt-users] Audio detection circuit to generate 'COR'

Tue Oct 6 15:03:47 UTC 2015

Hi guys,

Yes, I also can confirm that these modules have DIRTY transmitters and RF
synthesizers...And, their -loud- 2nd harmonics fall squarely in the busy
800MHz business/public service band. So, be careful with them, or you may 
have unwanted visitors knocking at your door!!! Without proper filtering, 
even with a small antenna, I'm sure their 2nd harmonic can be heard for 
miles!

Personally, I wouldn't put a lot of effort into building a repeater 
with these--my experience has been that they're not really usable for more 
than a "back yard" repeater (meaning perhaps 1/2 coverage), due to high 
synthesizer noise--you'll never get the receiver to hear very well.

As with everything, you mileage may vary--have fun and experiment! That's
what ham radio is about! The nice thing about this hardware is that it's
dirt cheap!  BTW, I'm specifically referring to the Dorji DRA818U/DRA818V
modules here, of which I've got several.

73, David KB4FXC

On Tue, 6 Oct 2015, Steve Zingman wrote:

> Steve,
> Be aware that those transmitters are dirty.
> There is a note about a module using the same RF circuit on Doug's 
> HAMVIOP site.
> He suggests a filter. REQUIRED if you are going to drive a amp or even 
> connect it to a antenna!
> 
> 73, Steve N4IRS
> 
> On 10/6/2015 9:13 AM, Steven Donegan wrote:
> > Thanks. For my first full duplex repeater (for test/learning purposes) 
> > I am going with 2 of those modules and a 6 cavity duplexor (likely of 
> > the 'notch' variety). If it works out may put my Mirage BD-35 on the 
> > TX side before the duplexor and get ~16 watts for giggles.
> > Steven Donegan
> > KK6IVC General Class FCC License
> > Silver State Car #86
> > www.sscc.us
> >
> > ------------------------------------------------------------------------
> > *From:* Steve Zingman <szingman at msgstor.com>
> > *To:* Steven Donegan <donegan at donegan.org>
> > *Sent:* Tuesday, October 6, 2015 6:10 AM
> > *Subject:* Re: Audio detection circuit to generate 'COR'
> >
> > I'll send you the info tonight when I get home. I have a couple of them.
> >
> >
> >
> > On 10/6/2015 9:10 AM, Steven Donegan wrote:
> >> Thanks Steve! I'll look into that as well.
> >> Steven Donegan
> >> KK6IVC General Class FCC License
> >> Silver State Car #86
> >> www.sscc.us <http://www.sscc.us/>
> >>
> >> ------------------------------------------------------------------------
> >> *From:* Steve Zingman <szingman at msgstor.com> 
> >> <mailto:szingman at msgstor.com>
> >> *To:* Steven Donegan <donegan at donegan.org> 
> >> <mailto:donegan at donegan.org>; "app_rpt-users at ohnosec.org" 
> >> <mailto:app_rpt-users at ohnosec.org> <app_rpt-users at ohnosec.org> 
> >> <mailto:app_rpt-users at ohnosec.org>
> >> *Cc:* "app_rpt-users at ohnosec.org" <mailto:app_rpt-users at ohnosec.org> 
> >> <app_rpt-users at ohnosec.org> <mailto:app_rpt-users at ohnosec.org>
> >> *Sent:* Tuesday, October 6, 2015 6:06 AM
> >> *Subject:* Audio detection circuit to generate 'COR'
> >>
> >> Steve COR or actually RUS "Receiver Un Squelch" is available in that 
> >> radio. You have to unsolder the shield to get to it.
> >>
> >> 73, Steve
> >>
> >>
> >>
> >> On 10/6/2015 8:56 AM, Steven Donegan wrote:
> >>> Well, it is a generic question - any radio without COR. The specific 
> >>> model in my case is a UHF radio module model # SA-828U: 
> >>> http://www.alibaba.com/product-detail/1W-5km-distance-SA828-U-uhf_60092524887.html?spm=a2700.7724857.29.62.Xbg6c5
> >>> Steven Donegan
> >>> KK6IVC General Class FCC License
> >>> Silver State Car #86
> >>> www.sscc.us <http://www.sscc.us/>
> >>>
> >>> ------------------------------------------------------------------------
> >>> *From:* Skyler Fennell <electricity440 at gmail.com> 
> >>> <mailto:electricity440 at gmail.com>
> >>> *To:* Steven Donegan <donegan at donegan.org> <mailto:donegan at donegan.org>
> >>> *Cc:* app_rpt-users at ohnosec.org <mailto:app_rpt-users at ohnosec.org>
> >>> *Sent:* Tuesday, October 6, 2015 5:47 AM
> >>> *Subject:* Re: [App_rpt-users] Audio detection circuit to generate 'COR'
> >>>
> >>> http://www.aaroncake.net/circuits/vidswitch.asp
> >>>
> >>> That might work, I use it for packet.
> >>>
> >>> What radio are you on?
> >>>
> >>> Sent from my iPhone
> >>>
> >>>
> >>>
> >>> On Oct 6, 2015, at 6:29 AM, Steven Donegan <donegan at donegan.org 
> >>> <mailto:donegan at donegan.org>> wrote:
> >>>
> >>>> Does anyone have a circuit that will take audio from a radio and 
> >>>> generate a pseudo COR signal for the URI-x? If so would you share 
> >>>> the circuit diagram?
> >>>>
> >>>> TIA
> >>>> Steven Donegan
> >>>> KK6IVC General Class FCC License
> >>>> Silver State Car #86
> >>>> www.sscc.us <http://www.sscc.us/>
> >>>> _______________________________________________
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> >>>
> >>>
> >>>
> >>>
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> >>
> >>
> >>
> >
> >
> >
> 
> 