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Author Topic: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas  (Read 1732 times)

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Offline py1dkw@yahoo.comTopic starter

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HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« on: March 12, 2024, 02:08:27 pm »
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
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Offline RFDx

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Re: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« Reply #1 on: March 13, 2024, 07:41:22 pm »
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.
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Offline py1dkw@yahoo.comTopic starter

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Re: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« Reply #2 on: April 16, 2024, 01:10:50 am »
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!
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Offline coppercone2

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Re: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« Reply #3 on: April 16, 2024, 10:59:50 am »
would this be empire loop antenna?
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Online A.Z.

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Re: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« Reply #4 on: April 16, 2024, 11:15:46 am »
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Offline py1dkw@yahoo.comTopic starter

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Re: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« Reply #5 on: April 23, 2024, 11:57:09 pm »
Unfortunately not. This Empire is a nice loop, but it is not the antenna used by HFH from Rhode & Schwarz.  I had a Faraday cage in my Lab and this receiver and another ESH2 were used to measure noise with a Line Stabilization Impedance network,  basically a line filter that isolates noise from the mains supply, so you can measure precisely. I had bought some fine Rohde &Schwarz &Schwarz equipment and their support sent me the available manuals. Lots of new capacitors are often needed to restore those equipment!
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Offline coppercone2

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Re: HFH ROHDE & SCHWARZ RECEIVER LOOP antennas
« Reply #6 on: April 24, 2024, 01:01:36 am »
it might work those antenna are used for some kind of official measurements
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