JMP1E is the ground connection for audio on the FM line out connector Removing that jumper can eliminate any ground loop between the audio cables. ( line-inMessage 1 of 7 , Feb 4View SourceJMP1E is the ground connection for audio on the "FM line out connector"Removing that jumper can eliminate any ground loop between the audio cables. ( line-in and line-out to soundcard.)However, there can still be a ground loop between USB cable and audio ground.in this case, a USB isolator is recommended.( it is possible to remove 2 components from USB input to do this... but I have NOT tried it, and it could cause loos of connection, or instability)Brucekf1zBTW, some USB soundcards such as the E-MU line, have ground lift switches on the bottom of the case
Thank you Tasa.
With regards to: ""Prevent unwanted ground loops! QSD (quadrature
sampling detectors) SDR is 90% audio technique it is always good that we
have ground star configuration instead several loops(audio in /out ,USB
cables to sound card and PC). In G59 and G11 you can lift ground
connection to prevent this problem type""
Apologies if this is very basic or has been answered before.
In practical terms, how do you lift ground connection on G11?
--- In mailto:GenesisRadio%40yahoogroups.com, Sinisa Tasic wrote:
>clarify several topics in last messages at Genesis
> Hello group,
> I shall try to
>Hump in center of spectrum is normal thing. The source can be
> and software type. This problem exist in solution such asQSD Genesis
> design but also in receivers with high speed AD converterssuch as
> Perseus.... The big difference is that Perseus is not usingspectrum
> to the 0Hz in QSD designs this part is always in themiddle! That it
> strange can you find me any spectrum analyzerwhich is without even a
> hump around 0 HZ?important for practical use that this hump is small as possible.
> It is
>can we do to decrease hump?
> - Prevent unwanted ground loops! QSD(quadrature sampling detectors)
> 90% audio technique it isalways good that we have ground star
> configuration instead severalloops(audio in /out ,USB cables to sound
> and PC). In G59 and G11you can lift ground connection to prevent this
> problem type . Also somesound card like EMU202, EMU204 have switches
> lifting groundconnection at one side. To finding optimum solution
> maxrejection noises and interferences it is necessary make
>there is no universal receipt!!
> - Use very good audio cables withperfect ground shield. Most of
> commercial available cables have verypoor quality and hot wire
> cable is collecting unwanted noises,signals from surround and PC
> HUB, AC switches...). Very goodquality audio cables(excellent with
> shied) with separatecables for L/R channels are good solution . To
> collectingunwanted signals with cables shield add some ferrite tubes
> coresand wind cable around cores or pass through it to prevent so
>common mode current ! You can use some ferrite tubes or cores from
> CRT display (cable for connection for PC was passing throughit). It
> good practice to put all cables through the ferritetubes-cores !
> solution for reducing unwanted noise andinterferences is small
> cables such as RG174 or some smallerone. It will enable very good
> rejection unwanted signals but practicallyis not easy way to put 2
> RG174 in one 3,5 male audio jack! Itis good practice that all cables
> not longer than it is necessary!! Shorter will always give good
> The RG174 is 50OHMs cableit is not good idea to have very long cable
> RG174 it is possiblein some case unwanted oscillation audio or RF
> driving stage inSDR transceiver or audio card!
> -Galvanic separation with audiotransformer. Good audio transformers
> such wide range of almost0-96KHZ is not easy find and they are
> One friend of mineuse this proposal for galvanic isolation from
> down and thisproposal is giving really very good results in his and
> tests! Theauthor of this article is IW3AUT
> to my friend Lada OK1UNL for this link.is possible to try every solution separately or combine severals.
>am giving guarantee that if you use some of proposed technique you
> obtain improvement in some cases it will very dramaticimprovement.
> is no universal receipt for this type of problemseven if you are
> brand name PC and sound cards!Genesis and I am using very effective way to carrier rejection
> 2. The
>transmit section. This type of solution can give carrier rejection
> 70-80dB. It is necessary to be dome slowly in several iteration asit
> explained in all assembling mauals. Good results is around50-55dB
> find results in .doc which I uploaded some times ago! Here is
> that you have reference point (max output power )and than count dB to
> level. All HF receivers are very sensitiveand they can receive very
> signals typically for G11 from -114 to-116dBm to -7dBm basic setup
> without additional RF and audio gain whatis more than 107dB! Because
> that it not strange that you can heardcarrier !!! IT is normal
> that if we increase frequency thatbalance for carrier rejection is
> good. It is not usual situationas it is described in message that
> worse at lowerfrequencies.
> 3. Unwanted image (opposite side band in classic design) itis
> reject with hardware adjustment from 45-55dB or more.Please see my
> results for G11 hardware adjustment measurements! Withsoftware
> it is possible image reject to 60-80 dB! For bothcarrier and image
> rejection please check in transmitter GSDR setup useDC block !
> 4. It is not clear such kind of echo you are hearing ? As Iexplained
> times before to check full hardware functionality ofG11 and G59 you
> need PC after you setup frequency (of course Iam expecting that Si570
> is working what is situation i almost100%)! If you connect antenna
> will hear some signals from bandsometime weak sometimes with low
> with very high pitchfrequency. The phones are connected to RX output
> connector to sound cardline in instead cable If you can hear this
> GSDR software that isproblem related for PC and GSDR setup!
> 5. If you plug in MIC in MIC G11jack or G59 mic jack and phones to
> jack instead cable youwill hear yourself as you start talking. The
> quality need to behigh. You can make choice with jumper between two
> audio gainposition. There is no delay ! But if you are listening
> withphones which is goiung from souind card out to G11 or G50 line
>you will hav edelay and this will confuse you because it is like a
> If you use this test with external speaker instead phones youwill
> microphonic effect what is normal situation because here isnot VOX
> untivox control! Use minimum mic gain and all otheradjustment make in
> setup !protection . GPA10 and G11 output transistor
> 6. Hardware high SWR
> are very robust. They are used in the majority commercial transceiver
> driverstage nowadays. First adjustment is to move control voltage for
> controlto +3.5V. Adjust direct and reflected power reading and than
>decrease this voltage to +2.2-+2.5 V.
>will help !
> I hope that my explanation
> VY 73 GL in SDR homebrew TasaYU1LM/QRP