Electronics > RF, Microwave, Ham Radio

HFH ROHDE & SCHWARZ RECEIVER LOOP antennas

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py1dkw@yahoo.com:
Friends, I had bought a wonderful receiver HFH very original, but no power cable and Loop antennas. Need to restore it. Does anybody has an idea how to build a loop for 20 to 30 MHz? I know there was 3 antennas in this set. Thank you for ideas on its restoration too! 73s. Sam

RFDx:
The original loops are part of a resonant input circuit that tunes synchronously with the frequency of the receiver. It's hard if not impossible to build your own loops without knowing the specifications of the original loops. The receiver fortunately has a 60 Ohm input with 12V phantom power supply where a a broadband, active monopole or loop antenna can be connected.  The antenna factor of the active monopole/loop has to be known in order to make field strength measurements.

py1dkw@yahoo.com:
Well, I was very lucky finding an 8 pin power connector for the HFH, switched it to mains 125 VAC and it is working after 25 years switched off!
But the upper bands above 7 MHz are not working. Could be a failure in the  the second oscillator ? I could get the diagram from Rohde und Schwarz, the meter in the 20 dB linear and 40 dB log range are  not working too. Nice to see it working!

coppercone2:
would this be empire loop antenna?

A.Z.:

--- Quote from: coppercone2 on April 16, 2024, 10:59:50 am ---would this be empire loop antenna?

--- End quote ---

are you referring to this one ?

https://www.recycledgoods.com/empire-devices-lp-205sc-loop-antenna-12/

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