Paul, No, I am not trying to discredit this line of approach at all. However, you should refer to the papers by Dr. Ulrich Rohde about problems with wide input filters and the amplitude headroom needed to get QP readings. They are eye-openers.
Neither the AR8000 nor the Yupiteru 7100 work at full sensitivity down to 150 KHz. I do not expect coverage is much different from what you get there, so you will have to compensate by calibrating the amplitude indication against a known source. Signal generators for low frequencies are not expensive. And since the _limit_ is upwards of 250 microvolts, low sensitivity is not in itself a problem, (except for QP) just a datum. I do not trust handheld equipment to have a lot of headroom when it is already subject to IM products for normal reception. Not that you can't use them, but you really have to be careful. This also applies to spectrum analyzers, especially with gain ahead of the instrument (one of Dr. Rohde's points). Thoer are two approaches here. One is to switch in an attenuator ahead of the receiver to see if the signal drops by the same amount as the attenuator, or by more. 3d order IM will drop 3 dB for every dB you put in front of the set, for example. Another is to note where these IM products show up, and not worry about them. You said you are shielding the AR8000. I had some luck shielding a Yupiteru. If I do this again I will probably replace the plastic shell with metal. For one thing, plastic is too weak, and putting heavy cables and antennas on it can break the cabinet and part of the RF board. When you finish getting your AR8000 going as an instrument, write it up. I am sure it will be of interest to many professionals who do not want to invest in more costly apparatus. Good luck! Cortland ====================== Original Message Follows ==================== >> Date: 04-Jan-97 14:23:16 MsgID: 1039-125936 ToID: 72146,373 From: Paul Rampelbergh >INTERNET:[email protected] Subj: Re: LOW COST mesurement equipment. (Was Shiep rules) Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Type: Text Sender: [email protected] Received: from ruebert.ieee.org (ruebert.ieee.org [199.172.136.3]) by hil-img-3.compuserve.com (8.6.10/5.950515) id RAA01477; Sat, 4 Jan 1997 17:21:29 -0500 Received: (from daemon@localhost) by ruebert.ieee.org (8.7.5/8.7.3) id GAA06931 for emc-pstc-list; Sat, 4 Jan 1997 06:01:11 -0500 (EST) Message-ID: <[email protected]> List-Post: [email protected] Date: Sat, 04 Jan 1997 11:32:03 -0800 From: Paul Rampelbergh <[email protected]> X-Mailer: Mozilla 2.0 (Win16; I) MIME-Version: 1.0 To: [email protected] CC: [email protected] Subject: Re: LOW COST mesurement equipment. (Was Shiep rules) References: <[email protected]> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: [email protected] Precedence: bulk Reply-To: Paul Rampelbergh <[email protected]> X-Resent-To: Multiple Recipients <[email protected]> X-Listname: emc-pstc X-List-Description: Product Safety Tech. Committee, EMC Society X-Info: Help requests to [email protected] X-Info: [Un]Subscribe requests to [email protected] X-Moderator-Address: [email protected] Hello, Interesting approach but a few errors are slip in your comments who jeopardize the creditability, on purpose or not, of alternate solutions. Criticism is easy, I prefer on this subject constructively. I understand when you are directly involved and have financial interests with and due to the existing rules, the best possibility remaining to you is to support the rules and to discredit opponents. OK, I'll understand your position but that's it. [email protected] wrote: > None of these receivers are ready for conducted tests (0.15 - 30 MHz). I maintain my statement, in Europe the frequency range for the AR8000 is from 100Khz to 1950 MHz without any gap, and it works. > The handheld scanners offer a bar-graph signal strength display which seems of limited use. I have noted scales of from 2 to 8 dB per division depending on the scanner. A unit such as the AOR AR8000 may offer a digital signal strength readout which will probably be more accurate than that. Yes on the AR8000 the signal strength (and all other control commands) can be controlled from a PC. The S meter reading (64 steps) is good and a conversion table to dB is not so difficult. Range sensitivity differences can be handled the same way by the PC. Better, you have complete spectrum analyzer capability, controlled by PC or not, for near field research of problem causing interference frequency's. Those can be recorded and used for OATL (or other means) frequency measurements avoiding complete spectrum analyzer wasted time. > However, none of these receivers are designed with the amplitude headroom needed for a precision measuring system. Since they do not use tuned preselectors... By the way, the AR8000 ,and others also, have input preselector filters. I agree they don't have tracking filters. Sorry, but major manufacturers propose also, for pre-compliance tests, receivers to they're customers without tracking filters. Are they useless? Do I have to mention to you who? > These radios also have something lacking on spectrum analyzers, a BFO. This is surprisingly useful for probing and identifying sources of emissions. Never heard about USB, LSB and CW? >.... I will say that so far I > have not seen any such radio suitable to be relied upon as a sole means of > measurement even for engineering purposes I hope you where able to discredit the whole subject, good job, but I disagree once more with you. Try harder, maybe someday you succeed. See my comment at the beginning. OTHER SUBJECT. I received from the author of the spark generator (using a gaslight igniter) the confirmation, it works fine and gives good results for initial testing. regards Paul Rampelbergh Wezembeek-Oppem (Belgium) ------------------------- **Primary Recipient: INTERNET:[email protected] ====================== End of Original Message =====================
