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REPAIR HP 86260A RF PLUG-IN
March 2009

The HP 86260A RF Plug-In is missing its Front Panel, Connectors, Knobs and side locking mechanism. Apart from that it appears to be complete, although I suspect that there may be major fault which is why it has been stripped for spares. It should be a useful learning curve for microwave signal generation and YIG (Yttrium-Iron-Garnet) Oscillators in particular.

Front and rear views
Top and bottom views
Left and right side views
The YIG Tuned Oscillator (A4) can be seen in the blue box and the Isolator & PIN Modulator (A5) in the grey casting on the LHS. The 3 PCB's are on the RHS: YIG Driver Assembly (A1 BN); ALC Assembly (A2 RD); and FM Assembly (A3 OR).

Minor work was required to fit a BNC socket for the Ext Input and resoldering a wire to the RF On/Off Switch. Connecting a temporary SMA to BNC cable instead of the rigid SMA cable and it's ready to test. Powered-up and much to my surprise it works!

Initial test setup
This may be a "Heath-Robinson" birds nest, with little consideration to cable losses, but at least it proves that the YIG Oscillator is working over the range 12GHz to 18GHz. Power leveling controls have no effect. Next step is to try and find another scrap unit that has the required front panel and parts. A Service Cable (08620-60032), or a 36 way Amphenol 'Blue' plug and socket to make up a cable, would help to trouble-shoot the 86260A outside of the 8620C Sweep Oscillator.

February 2010

Fitted a replacement front panel and latch from a scrap unit together with control knobs and a SMA to BNC flexible coax. Have not been able to find the correct N-type to SMA connector yet or the 2 small plastic knobs for the switches. Powered-up on a Variac and all seems to be working ok.

Need to carry out performance tests next but will need a HP 8470A RF Detector
 

March 2010

At 18GHz the cables, connectors, accessories such as attenuators & power splitters are all critical for attenuation, impedance mismatch, etc. The performance tests were completed as far as possible as I don't have some of the necessary test equipment (HP 779D Directional Coupler, HP 8470A Crystal Detector) and some parts are not suitable at 18GHz (BNC RF output, attenuators, cables). Even so, the 86260A does provide a swept or CW output from 12.4 to 18GHz at +5dBm max. Using a HP 086290-60045 Detector (originally from a 86290A RF Plug-In) does prove that the external leveling input is working.