[hpsdr] ANAN 10 28Mhz tx spectrum and generated birdie

[Roger Rehr W3SZ]

Dave,

Thanks for the post! I would recommend that you change the title of your 
description from "ANAN-10 as a Transverter Driver" to something else, 
because you didn't use an ANAN-10 in your tests. You used a TAPR Hermes 
card and an ANAN PA module.  While the results might well be similar to 
what would be seen with an ANAN-10, labeling your test results as coming 
from an ANAN-10 [and thus from Apache] is incorrect, and I think unfair 
to Abhi and Apache.  Your post, to which this is a response, also 
incorrectly identified the hardware that you tested as an ANAN-10.

I think it would have been acceptable and fair to surmise in a 
conclusion to your online article that the results might apply to an 
ANAN-10, as long as the title and lead-in to the article didn't imply 
that it WAS an APACHE-made ANAN-10 that you were testing when in fact it 
was not.

I have not worried here about harmonics from my multiple Hermes [and 
Atlas] units here, because the input filtering in my transverters 
eliminates the need for such concern.  But I agree that if someone had a 
transverter with a 28 MHz IF that had an input passband including up to 
56 MHz or even 84 MHz, then the harmonics would be a concern and an 
additional LPF would be necessary, as you rightly pointed out in your 
test of your TAPR Hermes card as described at the URL you posted.

I asked Abhi about his thoughts on the concerns expressed in this 
thread, and as always I got a quick, helpful, and carefully considered 
response.  Here is what he sent me:

1. The Hermes card on it's own is not intended to be used as a 
transmitter since it does not provide either LPFs or a T/R switch, when 
used at around 300mw or lower the harmonics on all HF bands will be 
around -30dB except on 6M where they are lower due to a 6M LPF which is 
on the Hermes Tx path, hence Hermes stand alone does not meet FCC 
requirements nor was it intended to on it's own,

2. When using a transverter @ 28Mhz with Hermes it is expected that the 
transverter will have a 10M BPF to eliminate the harmonics before mixing 
with the upconverter, the final Transverter PA will also have an LPF.

3. There is a low noise SMPS which converts 12v to 5v onboard, although 
well designed by Kjell, LA2NI expecting it to have no EMI radiation is 
trying to defeat the laws of physics , however, the SMPS switching 
frequency harmonics are very low and in no way effects the transmitted 
spectral purity.

4. The ANAN-10 PA has a bank of seven LPFs covering 160M through 6M, 
Hermes when used with the 10W ANAN PA meets and exeeds FCC requirements.

The user is seeing spurii a few hundred Khz above and below the 
fundamental, these are possibly generated by the Hermes card, he should 
in fact update the board firmware and reset the PowerSDR Mrx database to 
see if that resolves the issue if not the Hermes board he is using may 
require service, The spurii he is seeing are definitely not generated by 
the PA.

-----------------------------------end of comments from 
Abhi---------------------------------------

I've always found Abhi and Apache to be the "Best of the Best" when it 
comes to solving problems, answering questions, etc.  My experience here 
has always been that he goes beyond what would be expected even from the 
"Best of the Best" when potential issues or questions arise.

I am following this thread with interest, as I have several TAPR Hermes 
cards.  But I still call them Hermes cards, even though I have housed 
them in Apache ANAN-10 boxes :)

73,

Roger W3SZ

On 8/5/2016 12:45 PM, Dave wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Dom
>
> I saw nothing within -70dBC inband on my ANAN10 when using the xverter port
> on 28MHz . My Anan has been used on many 2/4m contests with a Transverter
> without complaints from my (VERY) locals
>
> This port does however have bad harmonics see
> http://g4fre.blogspot.co.uk/2013/11/anan-10-as-transverter-driver.html  
>
> Dave
> G4FRE
>
> -----Original Message-----
> From: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of
> Dominique Dehays
> Sent: 05 August 2016 17:31
> To:hpsdr at lists.openhpsdr.org
> Subject: [hpsdr] ANAN 10 28Mhz tx spectrum and generated birdie
>
> ***** High Performance Software Defined Radio Discussion List *****
>
>
>
> Hello ,
>
> after getting a local friend complaining about hearing me on several
> frequencies , I've measured the anan 10 output spectrum , and was
> surprised to find spuriis 295 and 590 Khz  each side of the carrier at
> -60db/-63dB. I know it is within FCC norms but it is really annoying.
> Another problem is that the anan generates a wide  drifting birdie in my
> 144Mhz receiver  ( of course a separate receiver not the anan). Anyone
> got the same problems?
>
> 73
> Dom
> _______________________________________________
> HPSDR Discussion List
>
>    
>

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