Hello,
I have purchased the directional coupler from a parted out HP 8515A which I want to use as a general purpose instrument for measurement across 45 MHz to 26 GHz. I have found the spec for the HP 8515A which shows its measurement level of -5 to -25 dBm. Does anyone know the limit of power I can safely push through this units internal directional coupler without risk of damage, once removed from the unit?
Thanks for any comment, anything you can add to help me with this question would be greatly appreciated.
I bought this unit from a used test equipment seller on ebay, his comments were:
"You are bidding on what is arguably the highest performance ultra-wideband directional coupler ever built by HP for the range 45MHz - 26.5GHz with a tested raw directivity better than 35dB at -20dB coupling over all the range. It is fitted with metrology grade 3.5mm SMA compatible connectors and could be a perfect addition to your microwave swept network analysis setup. Compared to the usual resistive VSWR bridges and autotesters usually used over this frequency range, it has much lower insertion loss and better performance, allowing for higher dynamic range measurements".
The seller advised me that this unit was not made to handle power but perhaps it might handle a few watts, hoping to find someone who knows for sure. I don't know that I will ever use it that way anyway but would like to know and won't try without real specs for that parameter.
My online Satcom notebook: http://imageevent.com/qdf_files/technicalgoodies
Thanks!
I have purchased the directional coupler from a parted out HP 8515A which I want to use as a general purpose instrument for measurement across 45 MHz to 26 GHz. I have found the spec for the HP 8515A which shows its measurement level of -5 to -25 dBm. Does anyone know the limit of power I can safely push through this units internal directional coupler without risk of damage, once removed from the unit?
Thanks for any comment, anything you can add to help me with this question would be greatly appreciated.
I bought this unit from a used test equipment seller on ebay, his comments were:
"You are bidding on what is arguably the highest performance ultra-wideband directional coupler ever built by HP for the range 45MHz - 26.5GHz with a tested raw directivity better than 35dB at -20dB coupling over all the range. It is fitted with metrology grade 3.5mm SMA compatible connectors and could be a perfect addition to your microwave swept network analysis setup. Compared to the usual resistive VSWR bridges and autotesters usually used over this frequency range, it has much lower insertion loss and better performance, allowing for higher dynamic range measurements".
The seller advised me that this unit was not made to handle power but perhaps it might handle a few watts, hoping to find someone who knows for sure. I don't know that I will ever use it that way anyway but would like to know and won't try without real specs for that parameter.
My online Satcom notebook: http://imageevent.com/qdf_files/technicalgoodies
Thanks!
OK, so a specified damage level of greater than +17 and maybe I can get away with +20 dBm, perhaps as high as +27 or more but I won't risk it higher than a max of +20 dBm/100 mw. I wonder what the limiting factor is, due to a small low power termination inside and or because of small micro circuit traces etc?
If anyone has a photo of the insides of one of these I'd love to see it just for the beauty of viewing a well engineered directional couplers internal goodies. I suppose, the schematic would be the same as any coupler of this type.
That was designed by Julius Botka and internally was called the "triax bridge". In fact it is not coupler, but a resisitive bridge with a thin-film resistor structure that probably sets the limitation for max power.
Interesting side note, Julius also did the design for the 2.4 mm connector, the 1.85 mm connector and the 1 mm connector.