[amsat-bb] Re: Using NW Bell 36250 as a signal source

[Ronald Long <rlong3@xxxxxxxxxxxxxxx>]

Gary W6RYO wrote:

 > The Northwest Bell model (36250) can be used as a signal source
 > for AO40 receive testing.

I have shared the following with Gary but will post it here for others.

OfficeMax has a similar 2.4GHz analog phone on a rebate special this week. 
After rebate it is only $10!

It is a Curtis Model TC967. The FCC ID is OK8 TC968HT02.  For those 
unfamiliar with the FCC site it is: http://www.fcc.gov/oet/fccid/ Enter the 
OK8 in the top box and the rest in the lower box. There are pdf documents 
including a frequency chart, block diagram, and full schematic.

Three channels on the Curtis phone (2401.244, 2401.341 and 2401.437) are 
within the AO-40 downlink band. For the full 2400 to 2404 (144 - 148) band 
there are 36 frequencies. These are not the same frequencies as Gary 
reported for the 36250. I haven't researched this but would have thought 
that all phones are channelized the same by FCC rule. But apparently not.

Here is another reason to own one of these phones. There has been a 
discussion of interference to AO-40 operations from these phones. The 
Curtis phone (and presumably most others) transmit on 50 different channels 
and only a few of them are within the AO-40 downlink. So if you experience 
interference and know the source all you have to do is ask them to shift to 
a different channel. The phones have a Scan button for this purpose.

If you don't know the location of the interfering phone and if you have 
your own phone you might just set it on the same channel as the 
interference and call Time and Temperature or some such. If your phone does 
not transmit on the exact frequency perhaps you can find a channel close 
enough to cause interference. After the other user experiences this 
interference and if they have read their manual they will know to push the 
Scan button. Problem solved.

ron.



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