Cortland: Very good point about the coax. Very low loss coax can be very expensive; I recall a comparison I did a couple of years ago where I need very low loss 7 meter cable useable up to 18 GHz. A Gore cable cost around $2500, a Storm cable was about $1100, and the cable I bought, United Microwave Type 190, cost me $175.
The difference was ruggedness and power capacity. But I didn't need an armored jacket, and I only wanted to use this on my spectrum analyzer. So the cable I got was delicate (don't step on it, don't coil it carelessly, don't try to pump 20 watts through it), but it yielded an attenuation of only 2 dB @ 1 GHz, 5 dB @ 5 GHz and 9 dB @ 18 GHz. So I went back to them and bought a whole bunch of cables, some as short as 1/2 meter. And after 2 years, my lab gorillas have only killed one cable. (Pretty good deal.) Regards, Ed ------------------------ From: Cortland Richmond <72146....@compuserve.com> Subject: Re: Two un-related questions... Date: Sat, 5 Dec 1998 00:54:32 -0500 To: Jim Eichner <jeich...@statpower.com>, ieee pstc list <emc-p...@ieee.org> > Re that amplifier calibration... you may find that if you can demonstrate > an ability to do what the cal lab does, as well as they do it, you may be > able to calibrate it yourself. The problem is, do you have standards which > are accurate enough to be able to say this, and prove it? In an atmosphere > where even test equipment manufacturers are presumed not certified to > calibrate their products, will your ability to do so be accepted? > > Since an 8447D can be had for not all that much more than the cost of > keeping it calibrated, you may wish to economize and do without. A > sufficiently low-loss coax is an extremely good substitute for a preamp. > Because a really good coax has no IMD to speak of, using it instead of an > amplifier can lower the noise floor so you can often see weaker signals > without an amplifier than with one! > > Cheers, > > Cortland > > > ====================== Original Message Follows ==================== > > >> Date: 04-Dec-98 20:11:05 MsgID: 1065-75365 ToID: 72146,373 > From: Jim Eichner >INTERNET:jeich...@statpower.com > Subj: Two un-related questions... > Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 > > > 1. Preamp Calibration: We are being quoted $400 - $500 CDN (say > $260-$330 US) to "calibrate" an HP8447D RF preamp. The quote tells us > that what we are getting for our money is a check of the return loss, > gain, and VSWR. This seems a little involved and a little pricey to me, > but it's the first RF preamp I've dealt with, so what do I know? I > intend to use the preamp between a wideband antenna (a bicon, log > periodic, or combo) and our spectrum analyzer, and I assume the preamp > isn't flat, so I need to enter correction factors vs. frequency for it. > That's all I was really after: a chart or graph of gain vs. frequency, > so that I can set up the antenna-preamp-analyzer combo properly for > pre-compliance testing. Does anyone have any comments on what I really > need to do here, and whether the price I'm being quoted is typical or > not? > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > j...@gwmail.monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). > > ---------------End of Original Message----------------- -------------------------- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 12/05/1998 Time: 09:41:41 -------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
