[App_rpt-users] Micor Squelch like available on APP?

[Bryan D. Boyle]

On 7/25/11 7:59 PM, Tim Sawyer wrote:
> Lu Venci,
>
> I found the same issue thought I did not measure it as you have. I 
> reverted to good-old Micor squelch and P/L reeds because I did not 
> feel that app_rpt DSP did as well as the Micor  in either case. 
> Sometimes 40 year old technology is still best.

I'm doing a hybrid of what you're doing, Tim; Scott Z built my 220 Micor 
bringing out both the COR signal and the discriminator audio; I use the 
Micor squelch circuit high for COR, and the DSP to decode the tone.  In 
my mind, one is a go/no go, the other is something that can be inferred 
from simple signal processing.

carrierfrom=usb
ctcssfrom=dsp

Gives me the best of both worlds (Micor squelch, as you say, thought 40+ 
years old, is the tops), and the flexibility to change tone without 
having to search out reeds (for testing, lid removal, etc.).

I have an issue to throw out...which kind of got me scratching my 
head....occasionally (and non-repeatably), when keying up the 
repeater...I'll get a building in volume rushing noise (think raster 
noise like on an unoccupied TV channel that increases in volume) that 
peaks and then goes quiet.  Incoming audio is there all the time...I was 
thinking it was desensing, but it is not every time I key up the 
machine, I've gone thru the duplexers to tweak them to >90db of notch 
(after cleaning up the caps and polishing the copper-to-copper mating 
surfaces for the coil/cap assembly...I'll send a photo if anyone is 
interested...) and am running only about 55w into the xmt side.

Coax is 1/2" superflex out to the polyphaser, (I'm not going to admit I 
have some other non-recommended from the polyphaser up the pole, ok?  
It's in the plan to replace, I have 140' of LDF4 ready to go...just have 
to get up on the roof...), SWR from the radio to the amp is <1.2, from 
the amp to the duplexer is <1.2, loss thru the cans is 1.7db, swr out of 
the cans into the superflex is 1.2...all audio paths are shielded (but 
not ground looped, I know how to build audio channels...), no connector 
adapters, all silver/gold/teflon, etc.

Has me scratching my head.  That it's not repeatable, but happens 
randomly has me thinking that it's static discharge?  Pole and tripod 
are bonded and grounded, antenna is a stationmaster-type (tram 1494 cut 
to length, lock screws in the center radiator are tight and 
lock-tighted, and it's a dc ground design, albeit with a fiberglass radome.

Thinking static build up/discharge?  Something else?  Anyone else run 
into this?  We can take this offline, but, seeing as we're all repeater 
geeks here...thought I'd throw it out for consideration.

Thanks all...

-- 
Bryan
In this world, you must be oh so smart or oh so pleasant.
Well, for years I was smart. I recommend pleasant.
You may quote me.

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