[amsat-bb] Re: Problems with my 9600 baud stuff

Andrew Glasbrenner glasbrenner@mindspring.com
Wed Aug 16 14:34:56 PDT 2006

I'm willing to bet your 910 has the same faulty oscillator module that mine 
did. Icom replaced mine under warranty as soon as I contacted them, but that 
was several years ago. The symptoms were the same, 3-4 khz on 2m, and 9-12 
khz offset on 70 cm that would not trim out....

73, Drew KO4MA

----- Original Message ----- 
From: "James Cottle" <jim_cott@earthlink.net>
To: "Thomas McDaniel" <tmcdanielsprint@earthlink.net>
Cc: "amsat bb" <amsat-bb@amsat.org>
Sent: Wednesday, August 16, 2006 1:22 PM
Subject: [amsat-bb] Re: Problems with my 9600 baud stuff

> Hi Tom,
>  Tnx for your advice. I have now diagnosed several problems
> successfully. 1) I am using RHCP, which makes signals from AO-51 weak,
> complicated by the fact that I have a 15KHz offset which is further
> complicated by doppler and 2) turns out that, when one puts the 910H in
> "satellite mode" the data port receive gets switched as well. This
> morning I was able to copy strong TECHSAT beacons throughout its pass
> and strong voice on ECHO (The passes conflict right now). THanks for
> your guidance. SOmone needs to document this stuff for others!!!! maybe
> on a web page somewhere (in my spare time). Once again you pointed me in
> the right direction. Thanks for the hints. The offset on the 910H is
> well known...what is NOT well known is that, when you get down and dirty
> in there, you cannot adjust it out with the standard XTAL PLL
> oscillator. I have some pretty good test gear here....all of the tools
> but none of the talent (hi hi).
> 73
> Jim
> N6FO
> Thomas McDaniel wrote:
>> Hi Jim,
>> AO-51 is RHCP for voice and LHCP for digital -- I'm using the KLM
>> 435-40CX with the switching relay.  I also find that GO-32 works
>> pretty well using LHCP so I leave my system set for LHCP when I'm
>> working digital.
>> I too use a SYMEK (TNC3S) TNC but I don't know about the IC910 hook
>> ups as I use an old modified FT-736.  If you have access to an
>> oscilloscope, you might want to look at the data out of the radio to
>> make sure that it is where it should be.  It seems like I heard that
>> there are separate data ports for each side of the IC-910 -- does sat
>> mode combine them or do you need to use somekind of a "Y" cable for
>> digital sats?  Hook-ups can be tricky.
>> I am surprised to hear about the frequency problems, while I haven't
>> used the IC-910, I have had good luck with other Icom equipment.
>> Being 15 KHz off on the UHF band will certainly be a problem tuning
>> the receive -- the data would be outside the passband!  I think I
>> would call Icom service and ask them about this.  If you are using
>> computer control (like SatPC32) you might be able to set an off-set to
>> compensate, but it still shouldn't be that far off -- its hard enough
>> to tune to compensate for doppler shift without an inaccurate receiver!
>> 73  Tom  n0ntx
>> ----- Original Message ----- From: "James Cottle"
>> <jim_cott@earthlink.net>
>> To: "Thomas McDaniel" <tmcdanielsprint@earthlink.net>
>> Sent: Wednesday, August 16, 2006 12:10 AM
>> Subject: Problems with my 9600 baud stuff
>>> Hi Tom,
>>>  Thank you for your generous offer. I am using an ICOM IC910h and
>>> interfacing it thru its mini DIN data port to a SYMEK 9600 TNC3. I
>>> was able to get a couple of passes of TECHSAT beacons thru and then
>>> something changed. Now I get no joy on any pass. I believe that I may
>>> have problems with the data port on the 910. I seem to be tracking
>>> the satellites fine, I can hear the downlink voice channels on ECHO
>>> with no problems.
>>>   Also, I am running a RHCP M2 432CP30. Is it true that ECHO wants to
>>> see LHCP? I may be seeing a serious degradation in signal strength
>>> due to the mismatch. I have never been able to get a good DCD from
>>> AO-51. I did get a couple of beacons from TECHSAT until something
>>> that I cannot identify changed. I may have switched to the MINI DIN
>>> port thinking it was a more elegant solution.
>>>   The frequency accuracy on the 910H is very poor. I tried, in vain
>>> to adjust the PLL and could not bring it in line. So i have ordered
>>> the CR-293 high stability XTAL option, hoping that this will pull the
>>> rig closer to its indicated frequency. It is typically 15 Khz off on
>>> U band and about 40KhZ off on L band. This makes tuning a real
>>> challenge on these short LEO passes. There is not a lot of
>>> documentation available that I have found on problems such as I am
>>> having, so I appreciate your help very much.
>>> Jim N6FO
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