Re: [Repeater-Builder] Micor UHF Sensivity
Sinad is done with a 1000 Hz tone at 3KHz deviation and requires a meter that can notch out the 1K tone and measure the remaining noise. 20dBQ is done with no modulation 2 Vac of sq noise w/ no carrier then generate unmodulated carrier till the ACVM indicates 0.2 Vac A major difference in the two usually meant an alignment issue or some sort of problem in the back end of the receiver. Is the meter 4 circuit showing that the channel element is on frequency, and have you checked the alignment of the IF? Proponets of the Sinad method claimed that their way of doing the alignment would actually improve the overall sensitivity since the radio was being tested while receiving audio. Milt N3LTQ - Original Message - From: Tim Sawyer To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 3:48 PM Subject: Re: [Repeater-Builder] Micor UHF Sensivity I'm getting about 0.35 for 12 db SINAD. But that looks about 10 db quieting to me. What I typically do is open the squelch with no signal and set the volume to 2 Vac then crank up the signal to 0.2 vac. Isn't that 20 db, or am I missing something? -- Tim :wq On Sep 6, 2010, at 10:46 AM, Eric Lemmon wrote: spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 1 2 dB SINAD method
Re: [Repeater-Builder] Micor UHF Sensivity
Yes, meter 4 shows the channel element is on frequency. If by IF alignment you mean injecting 11.7 Mhz and setting meter 4 to zero, yes I checked that. It was not far off. -- Tim :wq On Sep 7, 2010, at 9:11 AM, Milt wrote: Is the meter 4 circuit showing that the channel element is on frequency, and have you checked the alignment of the IF?
RE: [Repeater-Builder] Micor UHF Sensivity
Tim, Please confirm that you measured the sensitivity as 0.72 millivolts, or 720 uV- about 2400 times worse than the 0.3 uV you expect. Such a huge disparity points to a failed transistor or a shorted capacitor on the receive board. Perhaps your next step is to perform voltage checks and compare your readings to those in the manual. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Monday, September 06, 2010 10:11 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor UHF Sensivity I have a Micor base that was manufactured in the ham band. Model is C64RXB3196A-SP71. The receiver model number is TRE1241A-SP10 (420-450 Mhz). It came with 4 channels all tuned up and on frequency in the ham band. But the receiver is sensitivity is .72 mv for 20 db quieting on the best channel and .9 on the worst. I went through the alignment procedure and could not make any improvement. Obviously this is not meeting the .5 spec and I was expecting more like .3 or so. So my questions is what should I do to troubleshoot this? Is there some common Micor receiver failure parts or areas that I should be looking into? -- Tim :wq
Re: [Repeater-Builder] Micor UHF Sensivity
Eric, It's 0.72 microvolts. Not totally dead, just a bit numb. -- Tim :wq On Sep 6, 2010, at 10:24 AM, Eric Lemmon wrote: Please confirm that you measured the sensitivity as 0.72 millivolts, or 720 uV
Re: [Repeater-Builder] Micor UHF Sensivity
There are shield covers on the RX board that need to be pulled off and have the ground pins cleaned. I watched a Motorola service shop do that and the sensitivity came back. He turned to me and said you'd have been forever figuring that one out. Don't ask me why, but I saw it work. Chuck WB2EDV - Original Message - From: Tim Sawyer tisaw...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 1:11 PM Subject: [Repeater-Builder] Micor UHF Sensivity I have a Micor base that was manufactured in the ham band. Model is C64RXB3196A-SP71. The receiver model number is TRE1241A-SP10 (420-450 Mhz). It came with 4 channels all tuned up and on frequency in the ham band. But the receiver is sensitivity is .72 mv for 20 db quieting on the best channel and .9 on the worst. I went through the alignment procedure and could not make any improvement. Obviously this is not meeting the .5 spec and I was expecting more like .3 or so. So my questions is what should I do to troubleshoot this? Is there some common Micor receiver failure parts or areas that I should be looking into? -- Tim :wq
RE: [Repeater-Builder] Micor UHF Sensivity
Ah, what a difference a factor of 1,000 makes! Okay, the manual spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 12 dB SINAD method. Try connecting your service monitor directly to the input jack on the preselector and repeat the sensitivity measurement. If it is greatly improved, start looking at cables and connectors. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Monday, September 06, 2010 10:29 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor UHF Sensivity Eric, It's 0.72 microvolts. Not totally dead, just a bit numb. -- Tim :wq On Sep 6, 2010, at 10:24 AM, Eric Lemmon wrote: Please confirm that you measured the sensitivity as 0.72 millivolts, or 720 uV
Re: [Repeater-Builder] Micor UHF Sensivity
Hello Tim. I think the specs on your Micor are 402-430, But I could be wrong. What freq was it crystalled on before you retuned it? Also what is the frequency you tuned it on now? That gives us better information as to where it was and where you tuned it to. Butch, KE7FEL/r On Mon, Sep 6, 2010 at 11:11 AM, Tim Sawyer tisaw...@gmail.com wrote: I have a Micor base that was manufactured in the ham band. Model is C64RXB3196A-SP71. The receiver model number is TRE1241A-SP10 (420-450 Mhz). It came with 4 channels all tuned up and on frequency in the ham band. But the receiver is sensitivity is .72 mv for 20 db quieting on the best channel and .9 on the worst. I went through the alignment procedure and could not make any improvement. Obviously this is not meeting the .5 spec and I was expecting more like .3 or so. So my questions is what should I do to troubleshoot this? Is there some common Micor receiver failure parts or areas that I should be looking into? -- Tim :wq
Re: [Repeater-Builder] Micor UHF Sensivity
Stuff to try: 1. Verify that the LO multiplier chain is peaked correctly. I've seen a bunch of these that exhibit this symptom that had mistuned LO chains. 2. Feed the test signal into the RX directly. If you see good sensitivity, you know where to looks ;-) 3. Take each of the bottom cover shields off in order and clean the tabs. Put them back on and run a small screwdriver tip every 1/8 or so shorting the can to its ground. If you see an improvement get out an iron and solder it. I don't like doing this, but I haven't found an alternative that works. On 9/6/2010 12:11 PM, Tim Sawyer wrote: I have a Micor base that was manufactured in the ham band. Model is C64RXB3196A-SP71. The receiver model number is TRE1241A-SP10 (420-450 Mhz). It came with 4 channels all tuned up and on frequency in the ham band. But the receiver is sensitivity is .72 mv for 20 db quieting on the best channel and .9 on the worst. I went through the alignment procedure and could not make any improvement. Obviously this is not meeting the .5 spec and I was expecting more like .3 or so. So my questions is what should I do to troubleshoot this? Is there some common Micor receiver failure parts or areas that I should be looking into? -- Tim -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport)
Re: [Repeater-Builder] Micor UHF Sensivity
I'm getting about 0.35 for 12 db SINAD. But that looks about 10 db quieting to me. What I typically do is open the squelch with no signal and set the volume to 2 Vac then crank up the signal to 0.2 vac. Isn't that 20 db, or am I missing something? -- Tim :wq On Sep 6, 2010, at 10:46 AM, Eric Lemmon wrote: spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 12 dB SINAD method
Re: [Repeater-Builder] Micor UHF Sensivity
2V AC down to .2 v. AC is 20 DB quieting John VE3AMZ - Original Message - From: Tim Sawyer To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 3:48 PM Subject: Re: [Repeater-Builder] Micor UHF Sensivity I'm getting about 0.35 for 12 db SINAD. But that looks about 10 db quieting to me. What I typically do is open the squelch with no signal and set the volume to 2 Vac then crank up the signal to 0.2 vac. Isn't that 20 db, or am I missing something? -- Tim :wq On Sep 6, 2010, at 10:46 AM, Eric Lemmon wrote: spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 12 dB SINAD method
Re: [Repeater-Builder] Micor UHF Sensivity
Yea, I think 20 db quieting is more like 0.175 uV 12 db SINAD. -- Tim :wq On Sep 6, 2010, at 12:52 PM, John J. Riddell wrote: 2V AC down to .2 v. AC is 20 DB quieting
Re: [Repeater-Builder] Micor UHF Sensivity
The Micor book says less than 0.5 uV for 20db quieting or 0.35 for 12 db SINAD. So the two are in fact equivalent. I get better than 0.35 for 12 db SINAD but I don't measure 0.5 for 20 db quieting. I must be doing something wrong. -- Tim :wq On Sep 6, 2010, at 12:52 PM, John J. Riddell wrote: 2V AC down to .2 v. AC is 20 DB quieting John VE3AMZ - Original Message - From: Tim Sawyer To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 3:48 PM Subject: Re: [Repeater-Builder] Micor UHF Sensivity I'm getting about 0.35 for 12 db SINAD. But that looks about 10 db quieting to me. What I typically do is open the squelch with no signal and set the volume to 2 Vac then crank up the signal to 0.2 vac. Isn't that 20 db, or am I missing something? -- Tim :wq On Sep 6, 2010, at 10:46 AM, Eric Lemmon wrote: spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 12 dB SINAD method
RE: [Repeater-Builder] Micor UHF Sensivity
Not all voltmeters behave the same with complex AC waveforms (such as noise). Some of my Flukes are inaccurate at higher AC frequencies (like above a few hundred Hz) - and they're spec'ed that way. What kind of meter are you using, and where are you measuring (speaker terminals is where you should be measuring from)? Do you know what, exactly, the SP features/modifications are on your SP Micor? --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Monday, September 06, 2010 6:07 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor UHF Sensivity The Micor book says less than 0.5 uV for 20db quieting or 0.35 for 12 db SINAD. So the two are in fact equivalent. I get better than 0.35 for 12 db SINAD but I don't measure 0.5 for 20 db quieting. I must be doing something wrong. -- Tim :wq On Sep 6, 2010, at 12:52 PM, John J. Riddell wrote: 2V AC down to .2 v. AC is 20 DB quieting John VE3AMZ - Original Message - From: Tim Sawyer mailto:tisaw...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, September 06, 2010 3:48 PM Subject: Re: [Repeater-Builder] Micor UHF Sensivity I'm getting about 0.35 for 12 db SINAD. But that looks about 10 db quieting to me. What I typically do is open the squelch with no signal and set the volume to 2 Vac then crank up the signal to 0.2 vac. Isn't that 20 db, or am I missing something? -- Tim :wq On Sep 6, 2010, at 10:46 AM, Eric Lemmon wrote: spec is 0.5 uV without a preamp and 0.25 uV with a preamp, when using the 20 dB quieting method, and 0.35 and 0.175 respectively when using the 12 dB SINAD method
Re: [Repeater-Builder] Micor UHF Sensivity
I have tried with 3 volt meters and 2 SINAD meters: a Fluke 77, a Sinadder 3 (SINAD AC voltmeter) and a HP8924c. Pretty much same results with all. That is 20 db quieting around 0.7 uV, SINAD around 0.35. So what's the recommended meter? Should I trust the SINAD reading and chock the quieting reading up some unknown meter problems? Yes, measuring on the speaker terminals with no speaker. The Sinadder and 8924c have internal speakers but I suspect they are not loading the receiver. Yes. The Micor came with a 3 page document detailing SP71 modifications. Would you like me to scan and email you a copy? -- Tim :wq On Sep 6, 2010, at 3:30 PM, Jeff DePolo wrote: Not all voltmeters behave the same with complex AC waveforms (such as noise). Some of my Flukes are inaccurate at higher AC frequencies (like above a few hundred Hz) - and they're spec'ed that way. What kind of meter are you using, and where are you measuring (speaker terminals is where you should be measuring from)? Do you know what, exactly, the SP features/modifications are on your SP Micor? --- Jeff WN3A
RE: [Repeater-Builder] Micor UHF Sensivity
I have tried with 3 volt meters and 2 SINAD meters: a Fluke 77, a Sinadder 3 (SINAD AC voltmeter) and a HP8924c. Pretty much same results with all. That is 20 db quieting around 0.7 uV, SINAD around 0.35. So what's the recommended meter? Should I trust the SINAD reading and chock the quieting reading up some unknown meter problems? Very odd. I'd probably want to load the speaker PA; I usually just leave the speaker connected or use a load box. Yes. The Micor came with a 3 page document detailing SP71 modifications. Would you like me to scan and email you a copy? I'd be curious to see if any of the mods would affect AF response, IF bandwidth, or anything else that could be throwing off your numbers. IIRC, older Micor manuals didn't even have a 12 dB SINAD sensitivity spec, only a 20 dBQ spec/test procedure. That's what I remember always using as a pass/fail reference. Of course, SINAD is a better test, but you should expect an in-band Micor to still meet the quieting spec. --- Jeff WN3A
RE: [Repeater-Builder] Micor UHF Sensivity
Readers interested in this thread may find the following articles to be relevant: www.repeater-builder.com/measuring-sensitivity/measuring-sensitivity.html www.repeater-builder.com/tech-info/receiversensitivity.html 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Monday, September 06, 2010 4:00 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor UHF Sensivity I have tried with 3 volt meters and 2 SINAD meters: a Fluke 77, a Sinadder 3 (SINAD AC voltmeter) and a HP8924c. Pretty much same results with all. That is 20 db quieting around 0.7 uV, SINAD around 0.35. So what's the recommended meter? Should I trust the SINAD reading and chock the quieting reading up some unknown meter problems? Yes, measuring on the speaker terminals with no speaker. The Sinadder and 8924c have internal speakers but I suspect they are not loading the receiver. Yes. The Micor came with a 3 page document detailing SP71 modifications. Would you like me to scan and email you a copy? -- Tim :wq On Sep 6, 2010, at 3:30 PM, Jeff DePolo wrote: Not all voltmeters behave the same with complex AC waveforms (such as noise). Some of my Flukes are inaccurate at higher AC frequencies (like above a few hundred Hz) - and they're spec'ed that way. What kind of meter are you using, and where are you measuring (speaker terminals is where you should be measuring from)? Do you know what, exactly, the SP features/modifications are on your SP Micor? --- Jeff WN3A
Re: [Repeater-Builder] Micor UHF Sensivity
Yes, it is a DVP station. I have the DVP manual and I just checked the spec. It's the same 0.5 uV for 20 dBQ. The test procedure does say to load the speaker. I'll give that a try tomorrow. -- Tim :wq On Sep 6, 2010, at 8:17 PM, Jeff DePolo wrote: The SP docs show it being a DVP station. DVP receivers have wider (and flatter) IF filtering than standard Micor Sensitron receivers. They need a flatter IF passband to decode DVP properly. I'm wondering if that's why the 20 dBQ reading comes out higher than normal. I *thought* the A/S board was the same between DVP and standard stations, so the AF circuitry should be the same between the discriminator and the speaker terminals. --- Jeff -Original Message- From: Tim Sawyer [mailto:tisaw...@gmail.com] Sent: Monday, September 06, 2010 8:04 PM To: Jeff DePolo Subject: Re: [Repeater-Builder] Micor UHF Sensivity Here you go Jeff. Let me know what you see.
RE: [Repeater-Builder] Micor UHF Sensivity
Jeff, The DVP Micor uses a TRN8095A AS board, while the non-DVP stations use the TRN6006A board. The only differences involve the values of C231, C232, C233, C234, R234, and R237 which is used only on the DVP board. These components are all clustered at Test Points 12, 13, 14, and 15 on the schematic, and appear to affect only the squelch action. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Monday, September 06, 2010 9:20 PM To: Repeater-Builder@yahoogroups.com Cc: Jeff DePolo Subject: Re: [Repeater-Builder] Micor UHF Sensivity Yes, it is a DVP station. I have the DVP manual and I just checked the spec. It's the same 0.5 uV for 20 dBQ. The test procedure does say to load the speaker. I'll give that a try tomorrow. -- Tim :wq On Sep 6, 2010, at 8:17 PM, Jeff DePolo wrote: The SP docs show it being a DVP station. DVP receivers have wider (and flatter) IF filtering than standard Micor Sensitron receivers. They need a flatter IF passband to decode DVP properly. I'm wondering if that's why the 20 dBQ reading comes out higher than normal. I *thought* the A/S board was the same between DVP and standard stations, so the AF circuitry should be the same between the discriminator and the speaker terminals. --- Jeff -Original Message- From: Tim Sawyer [mailto:tisaw...@gmail.com mailto:tisawyer%40gmail.com ] Sent: Monday, September 06, 2010 8:04 PM To: Jeff DePolo Subject: Re: [Repeater-Builder] Micor UHF Sensivity Here you go Jeff. Let me know what you see.
