McChord AFB TRS

[Wilrobnson]

Ok, so McChord AFB has now implemented their UHF TRS....Control seemingly staying on 407.375. Problem is, I can't track it. Doing the math:

OFFSET (khz)= 1000* ((F1-F2)/(DEC1-DEC2))
OFFSET = 1000x ((409.500-407.375)/(520-435)) makes the offset 25.0khz

then

BASE = F1-(( DEC1-380)*OFFSET (Mhz)
BASE = 407.375- ((435-380)*0.025)) makes the base 406.000

However, the system doesn't track using this combo...So where'd I go wrong? TRUNKER is out of the question for me, so ?

Brett

 

[ChrisP]

Last time I was up near McChord, I had the system running in my PRO-93 just fine using the 406.0 mHz base and 25 kHz offset. I will double check the settings in the radio and let you know...

Chris Parris

 

[Wilrobnson]

Chris, remember that Fort Lewis right next door to McChord has their own 10 channel system. 406.000/25.0 works great on it. This AFB system is completely new within the past 3 weeks. It seems to be using 407.375, 409.300, 409.425, 409.500, 409.700, and 409.900- all of which I've previously logged as simplex ops at McChord (mostly at airshows).


Brett

 

[ChrisP]

Color me stupid - Of course I was listening to Ft.Lewis - Sorry about that!

So even if you can't track it, are there analog voice channels or is it all digital?

Does the scanner even try to track the data channel or does it just search through the frequencies looking for something to lock on?

- Chris

 

[Wilrobnson]

>>So even if you can't track it, are there analog voice channels or >>is it all digital?

Yes, it's all analog (for now)

>>Does the scanner even try to track the data channel or does it >>just search through the frequencies looking for something to >>lock on?

Yes, it's tracking it, but not passing conversations, when I know they're talking (2nd scanner)

Brett

 

[ChrisP]

Yes, it's tracking it, but not passing conversations, when I know they're talking (2nd scanner)

Brett

OK - well, since it's Motorola, the order of the freq's shoudn't matter, but it appears that the base & offsets may be different than we thought. I have run in to some UHF systems that are using 406.025 or 406.0125 as base frequencies. You might try plugging some different base freq's and see what happens.

I will have to make a trip up to McChord with trunker and see what it might say...

Chris

 

[Wilrobnson]

>>OK - well, since it's Motorola, the order of the freq's shoudn't matter, but it appears that the base & offsets may be different than we thought. I have run in to some UHF systems that are using 406.025 or 406.0125 as base frequencies. You might try plugging some different base freq's and see what happens.

I will have to make a trip up to McChord with trunker and see what it might say...
>>

Yep, I've tried about 20 different combos, done a ton of math (not my strong point either) and used the spreadsheet found elsewhere on this site, to no avail...I can't run TRUNKER in my current situation, so if you happen to be in the area...


Brett

 

[ChrisP]

Brett...

If my schedule holds up I should be coming up to the Tacoma area this weekend and hope to stop near McChord for a little trunker session. Have you had any further luck with thier TRS?

Chris Parris

 

[ChrisP]

McChord AFB Trunked System - Found Right Base Freq!

I spent a few hours near McChord AFB this afternoon and finally figured out the right base and offset to track the system...

Here's the system info:

McChord AFB - Motorola SmartZone system 842a, Site 1

407.375 - 010b
409.425 - 01dd
409.500 - 01e0
409.700 - 01e8
409.900 - 01f0

After much calculating, fiddleing and wild guesses, I found that the base frequency is 407.0 mHz, with a 25 kHz offset. System tracked fine with a PRO-2052 and PRO-93...

Chris

 

[Scanman5]

Thanks for the info

Greetings,

Will check out the trunk when I head for Portland on Wedsday.

Don from Shoreline

 

[Scanman5]

MaChord AFB Trunking

I tried twice with my Pro 95 Scanner. No luck. Need to study inputing fleet maps. Learning curve is uphill.

Don from Shoreline

 

[The-Mad-Titan]

Does anyone know if they're Analog or Digital? :?:

 

[ChrisP]

Does anyone know if they're Analog or Digital? :?:

McChord's TRS is almost all digital now. A very few analog talk-groups pop ip now and then.

- Chris

 

[hughwsharp]

What analog talkgroups do you speak of?

I'd love to see a hex code or two.

Those naughty, naughty little users.

 

[mattcawby]

Dose anyone know why there is a new ground ctl freq at Mcchord? Did the old one wear out?