I am pleased to report it works really well. I could detect no difference in the quality of received signals supporting the observed good phase noise 'measured' on the spectrum analyser.
I was initially a bit concerned at the high level of the source harmonic output. However, when connected to the Anglian it injection locks the internal 116MHz crystal oscillator, leading to a really clean injection signal.
Monitoring the 144MHz output, with the input 28MHz drive signal supplied by my R&S SMG low noise signal generator, the output spectrum was just as clean as with the internal ( unlocked) oscillator.
Driving the ZLPLL with a clean 10MHz GPS locked reference signal from the SMG, the Anglian signal sounded excellent. I am really pleased with these results, which I will be reporting in my talk at the EME Conference in three day's time!