[R-390] R-390 Digest, Vol 181, Issue 6

Sun May 5 19:11:03 EDT 2019

Congratulations John!

An impressive work!

Jose EA8DCP

El dom., 5 may. 2019 23:42, <r-390-request at mailman.qth.net> escribió:

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> Today's Topics:
>
>    1. R390A sensitivity and noise floor measurements
>       (jgedde at optonline.net)
>    2. Re: Latest Pics (Mike Bracey)
>    3. Re: Latest Pics (chacuff)
>    4. Re: Latest Pics (jgedde at optonline.net)
>    5. Re: Weak BFO Cured (Perry Sandeen)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 5 May 2019 16:24:53 -0400
> From: <jgedde at optonline.net>
> To: "'R390 \(E-mail\)'" <r-390 at mailman.qth.net>
> Subject: [R-390] R390A sensitivity and noise floor measurements
> Message-ID: <[email protected]>
> Content-Type: text/plain;       charset="us-ascii"
>
> After weeks of fiddling, tube swap optimizations, fixes, etc. I've got my
> R390A performing extremely well.  I have an HP 8644A signal generator I
> bought from the local scrap dealer for scrap value (it works fine) and was
> able to make the following measurements:
>
>
>
> Sensitivity: 0.55 uV for 10 dB S+N/N with a 30% modulated input.  It'll do
> better with 100% modulation..
>
>
>
> Noise floor: better than -137 dBm.  I can't go any lower with the 8644A
> without additional attenuators (they appear to add noise of their own) and
> my noise environment isn't great.  A screen room would be needed to go any
> lower.  I fiddled a bit with the IF gain and got an improvement from
> -132dBm
> with the standard IF gain setting at -7V at the diode load to -137 dBm.
> The
> judging factor was whether the signal could be detected.  At -137 dBm you
> could just make out that the sig gen was on or off.  My spectrum analyzer
> can go much lower in noise floor and confirms I wasn't just measuring RF
> leakage in the sig gen: it can see -137 dBm no problem if I set up the BW
> just right.
>
>
>
> While I am not able to repeat Chuck Rippel's -143 dBm and Sherwood
> engineering's 0.2 uV, I consider this quite good and I am very pleased.
> But
> to be fair, Sherwood doesn't state what they used as a source.  If it was
> 100% modulation, then I was able to get there.  I used the 30% modulation
> standard.  I tend to doubt -143 dBm noise floor to begin with as I have
> stated before.  I wonder if his sig gen is leaky?  Sherwood got -137 dBm as
> did I.
>
>
>
> Another good R390A day!
>
>
>
> John
>
>
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 5 May 2019 20:33:43 +0000 (UTC)
> From: Mike Bracey <mikebracey at att.net>
> To: "'R390 (E-mail)'" <r-390 at mailman.qth.net>,  "jgedde at optonline.net"
>         <jgedde at optonline.net>
> Subject: Re: [R-390] Latest Pics
> Message-ID: <458964095.397288.1557088423953 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
>  Good job John. You're looking good!
> 73,
> Mike, KE5YTV
>
>     On Sunday, May 5, 2019, 1:35:47 PM CDT, jgedde at optonline.net <
> jgedde at optonline.net> wrote:
>
>  It's coming along nicely - almost done.? I've also restored the DX-100
> enclosure it came with.? Sensitivity issues are a thing of the past and I
> now only have two issues left.? A partially broken antenna relay (CBNC
> broken off) and an issue with the 1 kHz filter (which isn't a priority
> unless I get bored).?
>
> It needs a serial number stamped on the placard but I've no idea what to
> use
>
> John______________________________________________________________
> R-390 mailing list
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> Post: mailto:R-390 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ------------------------------
>
> Message: 3
> Date: Sun, 05 May 2019 15:41:23 -0500
> From: chacuff <chacuff at cableone.net>
> To: jgedde at optonline.net, "'R390 (E-mail)'" <r-390 at mailman.qth.net>
> Subject: Re: [R-390] Latest Pics
> Message-ID: <avtnsu96hjmk30xwq60l4x0o.1557088883893 at email.android.com>
> Content-Type: text/plain; charset=utf-8
>
>
>
> Sometimes the original serial number is penciled in under the tag.
> Something you would have to note before the panel refinish...lots of time
> it's stamped on the rear panel too...rubber stamp type of thing.CecilSent
> from my Verizon, Samsung Galaxy smartphone
>
> -------- Original message --------
> From: jgedde at optonline.net
> Date: 5/5/19  1:04 PM  (GMT-06:00)
> To: "'R390 (E-mail)'" <r-390 at mailman.qth.net>
> Subject: [R-390] Latest Pics
>
> It's coming along nicely - almost done.? I've also restored the DX-100
> enclosure it came with.? Sensitivity issues are a thing of the past and I
> now only have two issues left.? A partially broken antenna relay (CBNC
> broken off) and an issue with the 1 kHz filter (which isn't a priority
> unless I get bored).? It needs a serial number stamped on the placard but
> I've no idea what to
> useJohn______________________________________________________________R-390
> mailing listHome: http://mailman.qth.net/mailman/listinfo/r-390Help:
> http://mailman.qth.net/mmfaq.htmPost: mailto:R-390 at mailman.qth.netThis
> list hosted by: http://www.qsl.netPlease help support this email list:
> http://www.qsl.net/donate.html
>
> ------------------------------
>
> Message: 4
> Date: Sun, 5 May 2019 16:43:01 -0400
> From: <jgedde at optonline.net>
> To: "'chacuff'" <chacuff at cableone.net>, "'R390 \(E-mail\)'"
>         <r-390 at mailman.qth.net>
> Subject: Re: [R-390] Latest Pics
> Message-ID: <[email protected]>
> Content-Type: text/plain;       charset="UTF-8"
>
> My panel had already been refinished by the previous owner.  No stampings
> on the back.
>
>
>
> From: chacuff <chacuff at cableone.net>
> Sent: Sunday, May 5, 2019 4:41 PM
> To: jgedde at optonline.net; 'R390 (E-mail)' <r-390 at mailman.qth.net>
> Subject: RE: [R-390] Latest Pics
>
>
>
> Sometimes the original serial number is penciled in under the tag.
> Something you would have to note before the panel refinish...lots of time
> it's stamped on the rear panel too...rubber stamp type of thing.
>
>
>
> Cecil
>
>
>
>
>
>
>
> Sent from my Verizon, Samsung Galaxy smartphone
>
>
>
> -------- Original message --------
> From: jgedde at optonline.net <mailto:jgedde at optonline.net>
> Date: 5/5/19 1:04 PM (GMT-06:00)
> To: "'R390 (E-mail)'" <r-390 at mailman.qth.net <mailto:r-390 at mailman.qth.net>
> >
> Subject: [R-390] Latest Pics
>
> It's coming along nicely - almost done.  I've also restored the DX-100
> enclosure it came with.  Sensitivity issues are a thing of the past and I
> now only have two issues left.  A partially broken antenna relay (CBNC
> broken off) and an issue with the 1 kHz filter (which isn't a priority
> unless I get bored).
>
> It needs a serial number stamped on the placard but I've no idea what to
> use
>
> John
>
> ______________________________________________________________
> R-390 mailing list
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> Help: http://mailman.qth.net/mmfaq.htm
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
> ------------------------------
>
> Message: 5
> Date: Sun, 5 May 2019 22:42:08 +0000 (UTC)
> From: Perry Sandeen <sandeenpa at yahoo.com>
> To: r-390 at mailman.qth.net
> Subject: Re: [R-390] Weak BFO Cured
> Message-ID: <1871815025.438124.1557096128246 at mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
> Yo Bubba Dudes!.
> Dave Wise wrote: ? Some years ago my BFO gradually weakened and died.
> Replacing the tubedid not help.
> OK, question.? Did you try one with higher gain i.e. 6BZ6, 6JK6 etc?
>
> If not, do you think that it would have solved the problem?
> Regards,
> Perrier
>
>
>
>
>
>
> ------------------------------
>
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>
> End of R-390 Digest, Vol 181, Issue 6
> *************************************
>