[amsat-bb] Re: [suitsat2] Did Drew Hear Himself?

[Bill Ress]

Steve - - additional, you may recall the RX tests in the clean room at 
your place. The RX is very sensitive having a NF (which includes the 
front end SAW filter) of just under 5 dB.

Lou - thanks for commenting on what probably remains at the 70 CM input. 
I did some rough calcs and with the sensitivity of the RX and about 1.5" 
for an antenna, sub-microvolt signals will be heard. The 1 watt test 
Drew ran attests to that.

So what this all means is that the transponder function is only 
minimally impacted by the lack of a 1/4 wavelength antenna. We need to 
get the word out that most typically equipped 70 CM satellite stations 
will make it through. Right now most everyone is focused on the easy 
signals but the linear transponder is almost fully functional. The very 
sweet thing is that with the transponder functioning we can now verify 
that the SDX is spot on in every way designed (Nice job guys!!)

Another good test will be to exercise the command function. Now it will 
take a bit more power at the satellite which was by design anyway. I'm 
sure that's in the plan after the dust settles.

Regards...Bill - N6GHz


On 8/4/2011 3:30 PM, Louis McFadin wrote:
> The antenna consists of a portion that is encased in grey Epoxy.
> That part is about 1.5 inches long.
> It's probably good enough for strong signals to get through.
> SWR is not so important on a receive only antenna.
>
> On Aug 4, 2011, at 6:06 PM, Steven.Bible at Microchip.com wrote:
>
>> Hi Everyone,
>>
>> Glad to hear!  I was just concerned and wanted to be sure.  Then this
>> opens up a lot more experimentation from the ham community.
>>
>> Question - How do you think the uplink is being received with no
>> antenna?
>>
>>
>> Steven Bible
>> Applications Engineering Manager
>> Wireless Products Division
>> Microchip Technology Inc.
>> Office Phone: +1-480-792-4298
>> Mobile Phone: +1-480-384-0319
>>
>>
>> -----Original Message-----
>> From: suitsat2-bounces at tapr.org [mailto:suitsat2-bounces at tapr.org] On
>> Behalf Of Anthony Monteiro
>> Sent: Thursday, August 04, 2011 2:29 PM
>> To: suitsat2 at tapr.org
>> Subject: Re: [suitsat2] Did Drew Hear Himself?
>>
>> Dear Friends,
>>
>> The transponder is inverting. The third harmonic
>> would be highly distorted and opposite sideband!
>>
>> Also, I can confirm the transponder is working
>> from hearing my own transmissions. I also heard other
>> stations that were "ditters" on the downlink.
>>
>> 73,
>> Tony AA2TX
>> ---
>> On 8/4/2011 4:23 PM, Joe Fitzgerald wrote:
>>>
>>>
>>>> I am really wondering if Drew heard himself indirectly, and not
>> through
>>>> the transponder.  There's a 3X difference between the uplink and
>> downlink
>>>> frequencies.
>>>>
>>>> Thoughts?
>>>>
>>>
>>>
>>> Drew was appropriately skeptical himself, he notes in his report:
>> "Sounded
>>> VERY good, and cycled on and off with the telemetry."
>>>
>>> -Joe KM1P
>>>
>>>
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>>>
>>>
>>
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>
>
> Lou McFadin
> W5DID
> ARISS US Hardware manager
>
>
>
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