Re: [Repeater-Builder] UHF Preamplifier
Have you guys tried the Simrex (formerly GLB) helical resonator pre-amp? It's great for repeater applications. Very selective and moderate gain. If you're using Bp-Br type cans you don't need any further filtering. http://www.simrex.com/site/products/preselector/Preselector1.pdfhttp://www.simrex.com/site/products/preselector/preselector_diagram.pdfI haven't bought one in quite a few years, but the last one I got was in the $150 range.Dan N8DJP Date: Sun, 18 Dec 2005 08:26:10 -0800 From: [EMAIL PROTECTED]Subject: Re: UHF PreamplifierAt 12/17/2005 10:15, you wrote:I've got the same setup. I also have a 4-sectionCelwave bandpass filter between the duplexer andpreamp. I found that the 17dB gain was way too muchfor the receiver, and the noise level increaseddramatically, to the point that I had to tighten thesquelch settings. The sig strength metering went from10 to 14uA with no signal.Why is that such a bad thing? If you add a preamp to a RX your measured noise power doesn't increase, it means that the largest source of noise in your system is still your RX that there's still room for improvement.Unless you're really worried about dynamic range, the ideal setup would be one in which the total noise power added by the addition of the preamp equals the noise present at the front end of the RX. This should provide the best balance of system noise figure dynamic range. If a 10 to 14 uA change represents 3 dB, then you'd be all set at that point.I don't know what's up with your carrier squelch. A well-designed squelch circuit shouldn't care how much noise power is present at the front end. Perhaps there's another problem with the RX: low gain in an IF stage, limiter problem, etc. that's causing the discriminator output to change with input noise power.Bob NO6B__Do You Yahoo!?Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Re: [Repeater-Builder] UHF Preamplifier
Hi Dan, I have used several of them in the past. While they provide lots of preselection, they aren't great where NF is concerned. I believe a simple 2 section BP Cavity and GaAs device to follow would easily beat the GLB in performance; both in preselection and NF. Kevin Dan Hancock wrote: Have you guys tried the Simrex (formerly GLB) helical resonator pre-amp? It's great for repeater applications. Very selective and moderate gain. If you're using Bp-Br type cans you don't need any further filtering. http://www.simrex.com/site/products/preselector/Preselector1.pdf http://www.simrex.com/site/products/preselector/preselector_diagram.pdf I haven't bought one in quite a few years, but the last one I got was in the $150 range. Dan N8DJP Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
At 12/17/2005 10:15, you wrote: I've got the same setup. I also have a 4-section Celwave bandpass filter between the duplexer and preamp. I found that the 17dB gain was way too much for the receiver, and the noise level increased dramatically, to the point that I had to tighten the squelch settings. The sig strength metering went from 10 to 14uA with no signal. Why is that such a bad thing? If you add a preamp to a RX your measured noise power doesn't increase, it means that the largest source of noise in your system is still your RX that there's still room for improvement. Unless you're really worried about dynamic range, the ideal setup would be one in which the total noise power added by the addition of the preamp equals the noise present at the front end of the RX. This should provide the best balance of system noise figure dynamic range. If a 10 to 14 uA change represents 3 dB, then you'd be all set at that point. I don't know what's up with your carrier squelch. A well-designed squelch circuit shouldn't care how much noise power is present at the front end. Perhaps there's another problem with the RX: low gain in an IF stage, limiter problem, etc. that's causing the discriminator output to change with input noise power. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
At 12/17/2005 11:07, you wrote: Bob M. wrote: I found that the 17dB gain was way too much for the receiver, and the noise level increased dramatically, to the point that I had to tighten the squelch settings. Think about this for a minute, if the noise level increased, the squelch circuit would have seen MORE noise and rammed the squelch closed. What actually happened is, adding a better device in front of the receiver lowered the receivers total noise figure, decreasing the noise in the squelch circuit, requiring the squelch pot to be set tighter. Very common effect. Common? Must be another explanation, as you're talking apples oranges here w.r.t. noise. Remember this is FM, so more noise power at the front end doesn't mean more noise at the discriminator unless the limiter isn't being driven into limiting, which is probably what's happening. But adding a preamp can only add total noise power, never subtract. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
At 12/17/2005 10:21, you wrote: At 10:15 AM 12/17/2005 -0800, you wrote: I found that the 17dB gain was way too much for the receiver ---That's one reason I swear by Chip's stuff for over 15 year. He places stability and noise figure over gain. The result are preamps with extremely low noise figure, unconditional stability and reasonable gain (typically around 12 dB). Ken I thought they were around 16-17 dB. Chip claims 17 dB 500 MHz; I once measured 16. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] UHF Preamplifier
That all depends on witch pre-amp you buy what spec you need for your site noise. I also swear buy his product. Oregon Repeater Linking Group Mike Mullarkey 6539 E Street Springfield, OR 97478 www.orlg.org -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, December 18, 2005 8:36 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] UHF Preamplifier At 12/17/2005 10:21, you wrote: At 10:15 AM 12/17/2005 -0800, you wrote: I found that the 17dB gain was way too much for the receiver ---That's one reason I swear by Chip's stuff for over 15 year. He places stability and noise figure over gain. The result are preamps with extremely low noise figure, unconditional stability and reasonable gain (typically around 12 dB). Ken I thought they were around 16-17 dB. Chip claims 17 dB 500 MHz; I once measured 16. Bob NO6B Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
Think about this for a minute, if the noise level increased, the squelch circuit would have seen MORE noise and rammed the squelch closed. What actually happened is, adding a better device in front of the receiver lowered the receivers total noise figure, decreasing the noise in the squelch circuit, requiring the squelch pot to be set tighter. Very common effect. Common? Must be another explanation, as you're talking apples oranges here w.r.t. noise. Remember this is FM, so more noise power at the front end doesn't mean more noise at the discriminator unless the limiter isn't being driven into limiting, which is probably what's happening. But adding a preamp can only add total noise power, never subtract. Bob NO6B If what you are saying is correct, adding the preamplifier should have placed a receiver lacking in overall gain into full (or at least more) limiting. If so, this would have raised the noise level to the discriminator, thus tightening the squelch. He commented that he needed to set the squelch pot tighter, which means there was less noise present after the installation of the preamp. Maybe I didn't explain it well, but I have seen this effect before, even on the bench where extraneous signals quieting the receiver can be ruled out. Kevin YAHOO! GROUPS LINKS Visit your group "Repeater-Builder" on the web. To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Repeater-Builder] UHF Preamplifier
I am currently running a AR2 preamp on my MSF5000 repeator with a cellwave 526 duplexor. I was thinking if uogrsding to Lunar preamp, but can find no reference to them on the internet. If anyone has any contact information it would be appreciated. Thanks Mark KB1IOZ Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
mdnosliw wrote: I am currently running a AR2 preamp on my MSF5000 repeator with a cellwave 526 duplexor. I was thinking if uogrsding to Lunar preamp, but can find no reference to them on the internet. If anyone has any contact information it would be appreciated. I haven't heard anything about Lunar in years, but if you want the best in preamps, try DEMI or Angle: http://www.repeater-builder.com/rbtip/supplyindex.html#preamps Kevin Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
I've got the same setup. I also have a 4-section Celwave bandpass filter between the duplexer and preamp. I found that the 17dB gain was way too much for the receiver, and the noise level increased dramatically, to the point that I had to tighten the squelch settings. The sig strength metering went from 10 to 14uA with no signal. I ended up putting 7dB of attenuation between the preamp and the receiver, but still had too much gain. I later increased to a 10dB attenuator. The receiver metering is resting at about 10.5uA, the squelch got reset to what it was with nothing connected to the receiver at all, and there's just enough gain to offset the losses from the coax, duplexer, and filter, and still leave some for the received signals. If you aren't padding the preamp output down, you should seriously consider doing so. The preamps are made with all that gain so you can feed a lossy multicoupler with them; when feeding one receiver, you don't need or want all that gain. Bob M. == --- mdnosliw [EMAIL PROTECTED] wrote: I am currently running a AR2 preamp on my MSF5000 repeator with a cellwave 526 duplexor. I was thinking if uogrsding to Lunar preamp, but can find no reference to them on the internet. If anyone has any contact information it would be appreciated. Thanks Mark KB1IOZ __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
At 10:15 AM 12/17/2005 -0800, you wrote: I found that the 17dB gain was way too much for the receiver ---That's one reason I swear by Chip's stuff for over 15 year. He places stability and noise figure over gain. The result are preamps with extremely low noise figure, unconditional stability and reasonable gain (typically around 12 dB). Ken -- President and CTO - Arcom Communications Makers of state-of-the-art repeater controllers and accessories. http://www.ah6le.net/arcom/index.html We offer complete Kenwood TKR repeater packages! We are now an authorized Telewave Dealer! AH6LE/R - IRLP Node 3000 http://www.irlp.net Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] UHF Preamplifier
Bob M. wrote: I found that the 17dB gain was way too much for the receiver, and the noise level increased dramatically, to the point that I had to tighten the squelch settings. Think about this for a minute, if the noise level increased, the squelch circuit would have seen MORE noise and rammed the squelch closed. What actually happened is, adding a better device in front of the receiver lowered the receivers total noise figure, decreasing the noise in the squelch circuit, requiring the squelch pot to be set tighter. Very common effect. Kevin Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] UHF Preamplifier
Like others have said, Lunar doesn't exist any more. Angle Linear is the current company, and Chip Angle makes great products. However, if your ARR is working, you are likely not to experience any measurable improvement in performance by switching to something else (assuming the ARR you have is a GaAsFET). Personally I like Angle Linear's preamps a) because they work well, and b) I've never had one fail out of probably 30 or 40 in service on various bands, both ham and and otherwise. YMMV. And as others have mentioned, proper filtering before the preamp is almost always necessary (pass/reject duplexers often aren't enough). --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of mdnosliw Sent: Saturday, December 17, 2005 11:18 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] UHF Preamplifier I am currently running a AR2 preamp on my MSF5000 repeator with a cellwave 526 duplexor. I was thinking if uogrsding to Lunar preamp, but can find no reference to them on the internet. If anyone has any contact information it would be appreciated. Thanks Mark KB1IOZ Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
