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@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@tapr.org [mailto:suitsat2-bounces@tapr.org] On Behalf Of Anthony Monteiro Sent: Thursday, August 04, 2011 2:29 PM To: suitsat2@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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Lou McFadin W5DID ARISS US Hardware manager
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Bill Ress