Hmm. To measure the difference I only switched off power to the
preamp. This means the transverter was still looking at the output
ckt of the preamp and not direct to the antennas. Originally, I was
running Linrad 3.20 over a year ago when making these measurements. I
believe I saw 17 dB change with my WA2ODO preamps. The preamp gains ~ 25 dB.
Using MAP65v2 signal meter I see 10 with preamps off and 25 with them
on looking at cold sky.
73, Ed - KL7UW
At 06:19 AM 1/29/2013, Les Listwa wrote:
>The reason I bring it up is because of the current discussion
>concerning measurement of the noise floor with a preamp on and
>off. I remember seeing a difference in the " noise drop" shown by
>Linrad and that shown by WSJT. The fact that Ian measured a 15db
>noise drop with his 19db preamp using WSJT got me wondering again
>what Linrad would have shown. I would rerun the tests, but my 2M
>station is currently dismantled.
>Q. How did you measure the noise drop?
>A. I measured the noise drop by looking at a cold sky and then
>bypassing the preamp. Test 1 was a TS-2000 running WSJT
>directly. Test 2 was single channel IQ+ running Linrad. Same preamp
>into 4x20 array.
>Q. Was wsjt running on the output from Linrad or on some other hardware?
>A. No, different hardware, see above.
>While I realize this is a non-perfect test, just wondering if
>others have seen the same.
>Date: Tue, 29 Jan 2013 00:05:50 +0100
>From: Leif Asbrink <<mailto:email@example.com>leif(a)sm5bsz.com>
>Subject: Re: [Moon-Net] FT-736R vs TS-2000
>Content-Type: text/plain; charset=US-ASCII
>It is not clear to me what you mean here. How did you
>measure the noise drop? Was wsjt running on the output
>from Linrad or on some other hardware?
>I do not know the details on how the noise floor is computed
>in wsjt. If you look at the Linrad S-meter any signal
>within the passband would be included in the computed
>RMS power. Probably not so in wsjt.
>"Different audio cards" It is unclear to me how that enters
>the picture. What is the signal path in both cases?
>Leif / SM5BSZ
> > In the past, I seem to remember that I found that the accuracy of measuring
> > the " noise drop" was very much different when I used WSJT as compared to
> > using Linrad, with a difference if several db with the same preamp. Can
> > anyone confirm? It could be the fact I was using different audio cards.
> > Les
>Moon-Net posting and subscription instructions are at
After 4 weeks holidays in South America I back to Switzerland last week, now
embedded in my daily work I have time to re-start the IQ+ production. The
waiting list 2012 was properly close on December 23, thank you very much for
the 58 new IQ+ owners. During my holidays a new one start, the delivery now
is much faster, just 5 to 7 days after payment confirmation.
I'm very close to finish the material for batch01 (RevB) but new material is
already order to guarantee a permanent delivery.
I'm very glad to see more and more satisfied users using their radios and
for that reason soon I will add to my homepage a small pin board where you
can read directly the excellent reports about the IQ+ by their own users,
not by me !!
On December 2012 Leif, SM5BSZ did a extensive evaluation report for the IQ+,
I will publish a link on my homepage about his results. Thank you very much
for that Leif!!
But now is time to point to the IQ+ XT !!
Requested by several people I decide to initiate the process to design a
Software Define Radio Transmitter based on the IQ+ architecture. To avoid
long emails on the reflector you can read more about the IQ+ XT on my home
You will find there a extensive preliminary documentation regarding this new
radio coming soon. The IQ+ XT is not a conventional SDR transmitter, the
approach is complete different than most of the SDR transmitter you could
find until today.
Due the fact this is a preliminary information your feed back off the
reflector is welcome !!
73 de Alex, HB9DRI
Hello Fellow EME'ers I am in the process of getting QRV on 10Ghz EME with a 2,4m offset.
My plan is to combine 2 elisra SSPA amps. That is the type in the long grey box 12ghz used for AM TV link in germany.
I have one Amp but I like to have 2 combined for good ERP :O).
Does anyone have an amp that they would sell or trade for something good ??.
Best regards Peter OZ1LPR