47GHz Narrowband - 1999 a New Year
©Lehane Kellett - G8KMH
Well, the move of QTH over, the lab almost back together and alarmed, it's time to get on with some radio work. The test equipment available has grown and now includes an HP141T with 110MHz and 18GHz plug-ins (I'm still looking for a pre-selector!). An HP5342A 18GHz counter and an HP8620C sweeper with 6-12.4GHz module.
Also acquired is an EIP 590/96 head. This is normally used with the EIP 548A (opt 06) counter to cover the higher frequencies but is also ideal as a mixer for a spectrum analyser - at about one fifth of the price of the HP equivalent (HP 11970Q - nice if you can get one!). We used one at Martlesham last November with a Tek spec. an. and that is a direct connect. The Tek has an internal Diplexer for the IF and LO signals. For the HP one has to be constructed with an LPF at about 1.5GHz for the IF signal and HPF at c2.5GHz for the LO. All the time maintaining a nice 50R match and little ripple. Therefore there are some trade-offs to be made. The instrument isn't expected to be flat to 0.1dB. If it is flat to 3dB over 40-50GHz I'd be happy. It will mostly get used for checking the Gunn, aligning filters and multipliers, etc. When used with the marker source then frequency accuracy should be sufficient. I'd also be interested in it's performance at 76GHz......... More on the diplexer once it has been modelled with Aplac. G4FRE also has the same thoughts so it'll be interesting to see what we come up with. New! I've just got coming a 47G calibrated noise head. So we'll see how some of the HP WG22/WR28 mixer heads do against other diode mixers, especially the DB6NT unit.
Revision 1.1