[amsat-bb] Leo Bodnar ICOM IC-9700 Reference Injection Board

Sun Feb 16 07:08:28 UTC 2020

Thank You Mark for the answer and the detailed notes.
73 Kevin

On 2/15/2020 21:42, Mark Jessop wrote:
> In short, yes.
>
> I have performed phase noise measurements on my IC-9700, with and 
> without injection locking. I am currently using a Leo Bodnar Mini 
> GPSDO as the reference, though using a MiniKits injection board (Leo 
> wasn't selling his at the time). I had to do this kind of locking as 
> there was noticeable drift when attempting 70cm EME contacts with the 
> IC-9700 unlocked, which was causing degradation in decode performance. 
> With the radio locked there are no issues.
>
> The test equipment was a Symmetricom 5125A Phase Noise Test Set, and I 
> was using a 160 MHz Wenzel as a reference. The 5125A only works on 
> input signals up to 400 MHz, so for 70cm and 23cm I mixed the signal 
> down to ~30 MHz using a Minicircuits LAVI-2VH, with the LO generated 
> by a R&S SMA100B. The rig was powered from 2x 100Ah batteries, and the 
> GPSDOs were powered from a 5V linear bench supply.
>
> I tested:
> - (2m/70cm/23cm) Unlocked IC-9700, transmitting for ~5 minutes to let 
> the drift settle as best as it can.
> - (2m/70cm) IC-9700 + MiniKits Coupler board, driven with the MiniKits 
> GPS-9700 (+10 dBm)
> - (2m/70cm/23cm) IC-9700 + MiniKits Coupler board, driven with a Leo 
> Bodnar Mini GPSDO (maximum drive, which is ~+10 dBm I believe)
> - (2m only) IC-9700 + MiniKits Coupler board, driven with the R&S 
> SMA100B (+10 dBm)
>
> Plots of the results are here: https://imgur.com/a/iFi527l
>
> I guess the key point is that there is no degradation of transmit 
> phase noise observed when using any of the injection locking 
> solutions. While I did previously see some wide-band phase noise 
> differences between the MiniKits and Leo Bodnar LO's (as measured at 
> 49.152 MHz), this doesn't translate to a degradation at the output of 
> the transmitter. I'm not seeing the wide-band noise improvements when 
> injection locked that others have seen.
>
> There appears to be a slight improvement in close-in phase noise when 
> injection locked with the GPS-9700 and Mini-GPSDO (and a big 
> improvement when using the SMA100B, but that sig-gen costs 20x more 
> than the rig does), but I wouldn't read too much into the close-in 
> results as I only had time to run each measurement for ~5 minutes or 
> so. However, note that the test-set noise floor (shaded area) is 
> *well* below the measured results.
>
> 73
> Mark VK5QI
>
> On Sun, Feb 16, 2020 at 9:28 AM Kevin via AMSAT-BB <amsat-bb at amsat.org 
> <mailto:amsat-bb at amsat.org>> wrote:
>
>     I wonder if anyone who has all the needed equipment to test has
>     verified
>     that the output of the 9700 is still clean after this mod?
>
>         In the past ext reflock boards compared the radios osc to a gps
>     locked 10mhz signal and adjusted the trim voltage going to the
>     vctcxo so
>     levels were not touched, the radio was as clean or dirty as it was
>     when
>     it left the factory.
>        Now with this mod (if I understand it correctly) the main osc is
>     still running and they are just pumping a much stronger signal
>     into the
>     master osc area until it drowns out the original osc and the radio
>     locks
>     to it.  So the question comes up are they then overdriving the osc
>     chain
>     downline and distorting? and is the original osc signal still
>     there in
>     the background now as noise?
>
>     Might be a interesting project to find out.
>
>     73 Kevin wa7fwf
>
>
>
>     On 2/15/2020 14:08, Bob Hammond via AMSAT-BB wrote:
>     > This is a good explanation:
>     >
>     > "With the current firmware, users have observed frequency drift
>     when using
>     > narrow bandwidth modes. Using an external 10 MHz and the
>     firmware reduces
>     > the size of the frequency drifts by updating the corrections to
>     the master
>     > oscillator more frequently. The drift is still there,,,,, With
>     the 49.152
>     > MHz injector board and a good external 49.152 MHz GPS-locked
>     oscillator,
>     > the external oscillator locks the internal oscillator and the
>     drift issue
>     > is eliminated. The drift is probably not important on FM and
>     most may not
>     > notice the issue on SSB. But it is important to eliminate the
>     drift if you
>     > are using JT65 and similar narrow bandwidth modes."
>     >
>     > Copied from the Facebook ic-9700 group and a post by Peter
>     Freeman in reply
>     > to Tim Goodrich's question:
>     > https://www.facebook.com/groups/163460540873662/
>     >
>     > Bob W7OTJ
>     >
>     > On Sat, Feb 15, 2020 at 1:53 PM Bob Hammond
>     <propgrinder at gmail.com <mailto:propgrinder at gmail.com>> wrote:
>     >
>     >> Eric,
>     >>
>     >> I found much information on the design and benefits of a GPSDO and
>     >> reference board for the IC-9700 here:
>     >>
>     >> https://www.minikits.com.au/gps9700#wspr
>     >>
>     >> The Mini-Kits version is only slightly different than the Leo
>     Bodnar
>     >> version however the designs are virtually identical.
>     >>
>     >>
>     >>
>     http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=301
>     >>
>     >>
>     http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=352
>     >>
>     >> Bob W7OTJ
>     >>
>     >> On Sat, Feb 15, 2020 at 8:16 AM kd8drg.admin--- via AMSAT-BB <
>     >> amsat-bb at amsat.org <mailto:amsat-bb at amsat.org>> wrote:
>     >>
>     >>> I was wondering what the advantage is for using this board vs the
>     >>> standard 10Mhz external reference on the 9700?
>     >>>
>     >>> 73
>     >>> Eric
>     >>> WD8KNL
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