[hpsdr] Penny PTT unkeying spike - T/R sequencing?

[Roger Rehr]

I would like to second Tim's comment.

I have been regularly using five Mercury/Penelope combinations [some
Pene's are TAPR, some are Gerd's] for weak signal VHF work for a
nearly two years or so, and I have seen NO S meter or TR transition
issues such as have been described.  I have never had the software
lock up on TR transition or seen any of the Pene 'lock up' that Tom is
seeing.  Nor have I experienced the 'headphone pop' he reports.

This would suggest to me that he is seeing one of those
system-eccentric anomalies that can drive the affected individual
crazy [I know because I have been there with other pieces of gear],
but which can be very hard to track down.  My note is just to indicate
that I don't think it is a problem that all of us are having.

The solution of these problems does sometimes, however, lead to
identification of programming or other general 'issues' that were
otherwise unrecognized, so it will be interesting for us all to hear
the denouement, once the problem is solved.


73,

Roger Rehr
W3SZ
http://www.nitehawk.com/w3sz/osxhpsdrserver.htm


On Wed, Feb 2, 2011 at 11:12 AM, Tim O'Rourke <w4yn at earthlink.net> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Tom
> I have not seen or heard this in my setup, I am using Gerd's T/R board driving his Hercules Amp. I do not see it in panadaptor display or hear it. I have never had Penny hang in tx either.
> Tim W4YN
>
>
> -----Original Message-----
>>From: Tom Cathey <k1jj at comcast.net>
>>Sent: Feb 1, 2011 9:44 PM
>>To: hpsdr at lists.openhpsdr.org
>>Subject: [hpsdr] Penny PTT unkeying spike - T/R sequencing?
>>
>>***** High Performance Software Defined Radio Discussion List *****
>>
>>With a lot of email help from Joe/K5SD and Frank/WA1GFZ,  I have the new
>>HPSDR rig running!  Thanks much guys!
>>
>>In the past week I've done a lot of bench testing and find Penny to be a
>>very clean exciter. I especially like the IMD and opposite sideband
>>suppression figures. With Mercury, what a combination.
>>
>>Now, I've run across something that may need more refinement. I am out of
>>solutions. I am seeing (and hearing) the effects of a spike during PTT
>>UNKEY. One symptom is a small spike 2khz above the main carrier frequency.
>>To see and hear it, PTT key Penny on AM or FM while watching the Mercury
>>panadapter or other scopes - then UNKEY and you will see this pulse ramp up
>>as the main carrier drop down. It will last maybe 50 ms and be down about
>>-30db from main carrier. (At least on my rig)  On the Merc "scope" feature
>>you may see the tone oscillation as it cuts off, and faintly hear it in the
>>headphones.  My S-meter bangs up to about 40-60+ over and I hear a rushing
>>pop in the headphones for maybe 500 ms.  (T/R sequencing amiss?)
>>
>>On a separate receiver I can hear the after-spike as a clean carrier pulse,
>>weak, but still there.  I could be wrong, but I think my particular spike
>>level is somewhat higher than others because I compared it to Frank's Penny
>>over the telephone and found his pop, S-meter and spike level down lower,
>>but still there.
>>
>>** This 2kz removed spike may NOT be related to the sequencing timing
>>S-meter and headphone pop however.  I mentioned it for reference.
>>
>>I changed the firmware version and changed the PSDR to different versions
>>and saw no difference. I checked supplies for stability and ran many other
>>tests but had no luck in smoothing out this T/R sequencing.  If I disconnect
>>all cables except for the USB and power supply - and key Penny using the MOX
>>mouse, the spike is still there. Same with external keying.
>>
>>The problem is a number of times it seemed this T/R sequencing noise caused
>>Penny to loose its programming and lock into a full dead carrier of 500 mW.
>>I had to reboot and repower the hardware to recover.
>>
>>The reason I'm bringing it up is that I've had a lot of experience with T/R
>>sequencing homebrew transmitters and receivers and see the symptoms here. Is
>>it my particular lash up or do the rigs vary in this area? Maybe there is
>>something that can be done in firmware or software to lengthen or better
>>sequence  the T/R transition to smooth things out so that Penny  drops out
>>more quietly and the pulse is lower in the headphones, Smeter bang lower and
>>on the panadapter.  I checked with two others - one said he had the s-meter
>>bang and the other did not.
>>
>>Other than that, I dearly love the overall performance of the transceiver
>>and look to add on an MRI (-50db IMD) linear amplifier and go from there.
>>
>>Thanks again for all who have helped.
>>
>>BTW, Phil is working on that .bat file to permit audio line input to Penny.
>>Will post it when tested.
>>
>>73,
>>
>>Tom Cathey, K1JJ
>>
>>
>>
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>
> Tim O'Rourke
> W4YN at ARRL.Net
> Low Power Amateur Radio Rocks
> Member of Flying Pigs,ARCI,GQRP,RSGB,ARRL Life Member
> NHRA Life Member
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