Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
During receive mode try to measure the by-passed PA DC voltage if it exists then it may cause self oscillation within the PA disconnect this DC voltage and see. Aland Nate Duehr [EMAIL PROTECTED] wrote: Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It is NOT duplexed and the RX section turns off during TX, just a normal MASTR II mobile setup. The only modification done was to by-pass the PA and run the exciter output over to the Low-Pass Filter board in the PA section directly -- didn't need much power to make this link work with a 6 or 7 element yagi mounted outside, pointed at the repeater it's linking into. After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. It's not strong enough to receive it further than about one house away on an HT down the street, and I don't hear it one block over, but there in the house... permanent carrier on 145.46. (Unfortunately this is the output frequency of one of our club repeaters that's over 40 miles and behind a ridge from my house, and the repeater loses completely to the carrier coming from the link radio in the basement.) I attempted to figure out the mix math to see if that would be a normal thing to see when using that particular UHF RX frequency, but I'm honestly not very good at that. I figured I'd post and see if any of the list's gurus might have an explanation of why it might be doing this. Any thoughts? I might (just to see what happens) stuff the crystals in another MASTR II, tune it up, and see if the same thing happens, but if this could be explained mathematically, that would be more interesting. Hmm, what other info might you need... ahh... thinking back, the crystals might not have been ordered with high-side injection... I'd have to look at the ICM packing sheet, and it's at home. Nate WY0X - Check out the all-new Yahoo! Mail beta - Fire up a more powerful email and get things done faster.
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/27/2006 12:26 PM, you wrote: Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It's the LO multiplier chain that you're hearing. 145.460 * 3 + 11.2 = 447.580 (447.575). After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 10:19 AM, you wrote: You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. I forgot to mention: the reason you don't hear it on TX on an unmodified Mastr II is because the RX OSC 10V is cut off during TX, so there's no RX LO when TXing. Bob NO6B
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Aland services wrote: During receive mode try to measure the by-passed PA DC voltage if it exists then it may cause self oscillation within the PA disconnect this DC voltage and see. Aland Already done when the PA was by-passed, but thanks for the thought. Nate WY0X
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
I forgot to mention: the reason you don't hear it on TX on an unmodified Mastr II is because the RX OSC 10V is cut off during TX, so there's no RX LO when TXing. Bob NO6B I don't have a manual in front of me, so I have to ask the question here. If the 10V to the Rx oscillator board is cut off during Tx, how could you put a 5C element in the Rx and an EC in the Tx and still have the Tx EC element be compensated by the Rx 5C while transmitting? The Rx 5C ICOM would need the 10V in order to generate the compensation voltage. Or am I forgetting something? --- Jeff
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460...
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 10:49 AM, you wrote: Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460... If Nate has a neighbor that likes to listen to 152.925, then yes. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 10:49 AM, you wrote: I forgot to mention: the reason you don't hear it on TX on an unmodified Mastr II is because the RX OSC 10V is cut off during TX, so there's no RX LO when TXing. Bob NO6B I don't have a manual in front of me, so I have to ask the question here. If the 10V to the Rx oscillator board is cut off during Tx, how could you put a 5C element in the Rx and an EC in the Tx and still have the Tx EC element be compensated by the Rx 5C while transmitting? The Rx 5C ICOM would need the 10V in order to generate the compensation voltage. Or am I forgetting something? Nothing forgotten - the ICOM still gets 10 V, just not 10 V for the oscillator. There are two separate 10 V feeds to the RX: one for the LO oscillator one for everything else. Bob
Re: RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Not quite ... I believe he stated this radio package is being used at home - reason for the problem being discussed in the first place. The 145.45833 MHz birdie seems to be interferring with his ability to hear a 2 meter repeater output. A 152.925 MHz birdie may not cause a problem in his neighborhood. Neil - WA6KLA - Original Message - From: Jeff DePolo [EMAIL PROTECTED] Date: Tuesday, November 28, 2006 10:49 am Subject: RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460...
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Bob Dengler wrote: At 11/28/2006 10:49 AM, you wrote: Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460... If Nate has a neighbor that likes to listen to 152.925, then yes. Bob NO6B It's reealy weak, Jeff. I'll probably move the ICOMs into a Station just to get a little more shielding first just to see if it helps, and then order crystals if that doesn't work... Guess I could just move the RX ICOM first and see how bad it is before futzing around with tuning the TX side. It probably doesn't help that the cables going to the PC aren't coming out of the case via any kind of feed-through caps, etc... bad Nate, no donut. They probably make nice antennas at VHF. :-) If it's in a Station, I can pull the audio and and signals needed off the backplane, which have already been nicely isolated from the guts of the radio with the built-in feed-through caps, etc - of course. I was just wanting to not waste a complete Station shelf on a link radio that only needs 250mW to be full-quieting or darn near close to it. And... I'll have to find a Station that was built as a Remote with the T/R relay if I feel like using one antenna... or re-jumper everything and put in an LPF board that has a T/R relay in it. (Sheesh, I'm usually ripping those OFF the LPF board if I don't have an LPF board with a Z-matcher on it to use in a PA!) Actually, come to think of it, I don't really want to waste a UHF PA deck... maybe will just split the thing to two antennas but set it up for half-duplex operation... easy enough to figure out. Just gotta dig through the system board and 10V regulator LBI's to get the right jumper config. Well... hmm. We do have a 40W UHF PA deck that's marked questionable... I could see what's wrong with it... if anything... 40W into the 6-element link yagi bore sighted on the repeater... you know, knowing my luck, I'll just light up the whole Front Range and cause myself multi-path problems... (snicker... damn Murphy!). (Not to mention making UHF unusable at my QTH overall... ha!) I seem to recall Dave Cameron VE7LTD had just mentioned he'd recently played with the remote audio card to get audio in/out for something he was working on... normally that card is tossed in the junque box around here, along with the transformer for the 4-wire audio, so I've never played with them. Maybe I'll have to pester him for his notes. I think one of the Stations I acquired recently still had all the cards in the shelf and various do-dads still in it and it was configured as a remote w/o repeat... ahh the possibilities... And I thought I was DONE building the link radio two weeks ago! :-) LOL! Thanks guys, cool discussion. Nate WY0X
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 12:23 PM, you wrote: Bob Dengler wrote: At 11/28/2006 10:49 AM, you wrote: Not quite, as 145 MHz will never make it through the UHF helicals. It's just leaking out of the RX case. Neil's got the easiest solution: order a high-side LO xtal for your 447.575 RX. Bob NO6B But that will just move the problem somewhere else...up to 152.925 where you might make even more enemies than on 145.460... If Nate has a neighbor that likes to listen to 152.925, then yes. Bob NO6B It's reealy weak, Jeff. I'll probably move the ICOMs into a Station just to get a little more shielding first just to see if it helps, and then order crystals if that doesn't work... Guess I could just move the RX ICOM first and see how bad it is before futzing around with tuning the TX side. It probably doesn't help that the cables going to the PC aren't coming out of the case via any kind of feed-through caps, etc... bad Nate, no donut. They probably make nice antennas at VHF. :-) If it's in a Station, I can pull the audio and and signals needed off the backplane, which have already been nicely isolated from the guts of the radio with the built-in feed-through caps, etc - of course. I was just wanting to not waste a complete Station shelf on a link radio that only needs 250mW to be full-quieting or darn near close to it. If you have an MVP lying around, you might have better luck with it. It's I/O connector has feedthrough caps on each line, just inside the case. I do hear LO leakage out of them too, but not quite the level you experience. Bob NO6B
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
At 11/28/2006 01:06 PM, you wrote: Nothing forgotten - the ICOM still gets 10 V, just not 10 V for the oscillator. There are two separate 10 V feeds to the RX: one for the LO oscillator one for everything else. Bob Confused. The ICOM *is* the oscillator, and it only has one 10V input pin. Or are you saying that the multiplier chain is what gets turned on and off? --- Jeff I don't have the manual here, but on every radio I convert to duplex operation I have to strap the RX OSC line to the 10 volt feed, otherwise the RX signal goes away (replaced with noise, not a muted RX) everytime I key the TX. I'm assuming here that without 10 V on the RX OSC line there is no RX OXC, hence no LO. Bob NO6B
[Repeater-Builder] spur from UHF MASTR II mobile - link radio
Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It is NOT duplexed and the RX section turns off during TX, just a normal MASTR II mobile setup. The only modification done was to by-pass the PA and run the exciter output over to the Low-Pass Filter board in the PA section directly -- didn't need much power to make this link work with a 6 or 7 element yagi mounted outside, pointed at the repeater it's linking into. After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. It's not strong enough to receive it further than about one house away on an HT down the street, and I don't hear it one block over, but there in the house... permanent carrier on 145.46. (Unfortunately this is the output frequency of one of our club repeaters that's over 40 miles and behind a ridge from my house, and the repeater loses completely to the carrier coming from the link radio in the basement.) I attempted to figure out the mix math to see if that would be a normal thing to see when using that particular UHF RX frequency, but I'm honestly not very good at that. I figured I'd post and see if any of the list's gurus might have an explanation of why it might be doing this. Any thoughts? I might (just to see what happens) stuff the crystals in another MASTR II, tune it up, and see if the same thing happens, but if this could be explained mathematically, that would be more interesting. Hmm, what other info might you need... ahh... thinking back, the crystals might not have been ordered with high-side injection... I'd have to look at the ICM packing sheet, and it's at home. Nate WY0X
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It's the LO multiplier chain that you're hearing. 145.460 * 3 + 11.2 = 447.580 (447.575). After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. --- Jeff -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.14.17/553 - Release Date: 11/27/2006 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * 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] spur from UHF MASTR II mobile - link radio
Well, since 145 is about 1/3rd of 447, let's see how it comes out. 145.46 * 3 = 436.38 MHz. 447.575 - 436.38 = 11.195 MHz Let me guess; the IF in that receiver is close to, or exactly that frequency! I'm sure the radio uses a much lower frequency crystal and multiplies it up to get to 450 MHz. The last stage is probably a tripler; the ones before it are probably doublers or triplers as well. You might be able to add some shielding around the multiplier stages, if none is there already. Lowering the gain in the stage that's producing the 145 MHz signal might also reduce its output enough to help. Changing to the opposite injection will definitely help, but then you'd need to go through the whole calculation again to find out what other frequency it'll wipe out. Bob M. == --- Nate Duehr [EMAIL PROTECTED] wrote: Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It is NOT duplexed and the RX section turns off during TX, just a normal MASTR II mobile setup. The only modification done was to by-pass the PA and run the exciter output over to the Low-Pass Filter board in the PA section directly -- didn't need much power to make this link work with a 6 or 7 element yagi mounted outside, pointed at the repeater it's linking into. After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. It's not strong enough to receive it further than about one house away on an HT down the street, and I don't hear it one block over, but there in the house... permanent carrier on 145.46. (Unfortunately this is the output frequency of one of our club repeaters that's over 40 miles and behind a ridge from my house, and the repeater loses completely to the carrier coming from the link radio in the basement.) I attempted to figure out the mix math to see if that would be a normal thing to see when using that particular UHF RX frequency, but I'm honestly not very good at that. I figured I'd post and see if any of the list's gurus might have an explanation of why it might be doing this. Any thoughts? I might (just to see what happens) stuff the crystals in another MASTR II, tune it up, and see if the same thing happens, but if this could be explained mathematically, that would be more interesting. Hmm, what other info might you need... ahh... thinking back, the crystals might not have been ordered with high-side injection... I'd have to look at the ICM packing sheet, and it's at home. Nate WY0X Yahoo! Music Unlimited Access over 1 million songs. http://music.yahoo.com/unlimited
RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Jeff is correct It's the rx xstal freg x9 16.1602037 x 9 = 145.46 ish 73 Don W5DK -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jeff DePolo Sent: Monday, November 27, 2006 2:27 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It's the LO multiplier chain that you're hearing. 145.460 * 3 + 11.2 = 447.580 (447.575). After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. --- Jeff -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.14.17/553 - Release Date: 11/27/2006 Yahoo! Groups Links
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Hi ... 447.575 MHz - 11.2 MHz (Intermediate Frequency) = 436.575 MHz (output of the receiver multiplier injection chain) divided by 3 = 145.45833 MHz. Try high side injection ... that frequency will come out to 152.925 ... Neil - WA6KLA - Original Message - From: Nate Duehr [EMAIL PROTECTED] Date: Monday, November 27, 2006 11:54 am Subject: [Repeater-Builder] spur from UHF MASTR II mobile - link radio Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It is NOT duplexed and the RX section turns off during TX, just a normal MASTR II mobile setup. The only modification done was to by-pass the PA and run the exciter output over to the Low-Pass Filter board in the PA section directly -- didn't need much power to make this link work with a 6 or 7 element yagi mounted outside, pointed at the repeater it's linking into. After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. It's not strong enough to receive it further than about one house away on an HT down the street, and I don't hear it one block over, but there in the house... permanent carrier on 145.46. (Unfortunately this is the output frequency of one of our club repeaters that's over 40 miles and behind a ridge from my house, and the repeater loses completely to the carrier coming from the link radio in the basement.) I attempted to figure out the mix math to see if that would be a normal thing to see when using that particular UHF RX frequency, but I'm honestly not very good at that. I figured I'd post and see if any of the list's gurus might have an explanation of why it might be doing this. Any thoughts? I might (just to see what happens) stuff the crystals in another MASTR II, tune it up, and see if the same thing happens, but if this could be explained mathematically, that would be more interesting. Hmm, what other info might you need... ahh... thinking back, the crystals might not have been ordered with high-side injection... I'd have to look at the ICM packing sheet, and it's at home. Nate WY0X Yahoo! Groups Links
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
I'm pretty sure the IF is 11.2MHz on a GE radio. On 11/27/06, Bob M. [EMAIL PROTECTED] wrote: Well, since 145 is about 1/3rd of 447, let's see how it comes out. 145.46 * 3 = 436.38 MHz. 447.575 - 436.38 = 11.195 MHz
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Users of MII mobiles as repeaters and/or base stations: You should expect interference when you cut corners to save a buck and use a mobile for a repeater. The mobile has no shielding to prevent RF entry or exit, none of the leads are in/out of the Rx and Tx are bypassed as in the MII stations! Mobile sets were never designed for this purpose. If you put a mobile on the air as a station and do not receive or give interference to others, consider yourself lucky. Fred W5VAY - Original Message - From: DK To: Repeater-Builder@yahoogroups.com Sent: Monday, November 27, 2006 2:40 PM Subject: RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio Jeff is correct It's the rx xstal freg x9 16.1602037 x 9 = 145.46 ish 73 Don W5DK -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jeff DePolo Sent: Monday, November 27, 2006 2:27 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] spur from UHF MASTR II mobile - link radio Hi guys, Built a link radio out of a MASTR II mobile a while back. 444.575 TX, 447.575 RX. It's the LO multiplier chain that you're hearing. 145.460 * 3 + 11.2 = 447.580 (447.575). After having the link installed in my basement for a few days, I realized that it's throwing a fairly strong dead carrier on VHF at 145.460 or thereabouts, but ONLY when it's sitting idle in Receive. When the radio is transmitting the carrier generated by the receiver disappears. You don't hear it when the radio is TXing because the T/R relay disconnects the receiver from the antenna. --- Jeff -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.409 / Virus Database: 268.14.17/553 - Release Date: 11/27/2006 Yahoo! Groups Links
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
FHS wrote: Users of MII mobiles as repeaters and/or base stations: You should expect interference when you cut corners to save a buck and use a mobile for a repeater. The mobile has no shielding to prevent RF entry or exit, none of the leads are in/out of the Rx and Tx are bypassed as in the MII stations! *Mobile sets were never designed for this purpose.* If you put a mobile on the air as a station and do not receive or give interference to others, consider yourself lucky. Fred W5VAY Fred missed that this isn't a repeater. But thanks for the reminder Fred. I agree with you on not using mobiles most of the time. For everyone else... I'm sitting here slapping my forehead and saying, Duh. I was (for some unknown reason) trying to do external mix math on the numbers instead of simply subtracting the IF and then dividing... what a maon. Thanks for the (rather obvious now that I see it) help, all. Guess I'll try two things... put the crystals in a station and perhaps with a little better shielding I can lower the effect for now of the mix in the house... short-term, and then order up the high-side injection crystals for the rig and retune when they arrive... Nate WY0X
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
You could add a little RC or coax stub suck out trap tuned to the offending frequency, placed on the RX input connector. Chuck WB2EDV - Original Message - From: Nate Duehr [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, November 27, 2006 7:45 PM Subject: Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio FHS wrote: Users of MII mobiles as repeaters and/or base stations: You should expect interference when you cut corners to save a buck and use a mobile for a repeater. The mobile has no shielding to prevent RF entry or exit, none of the leads are in/out of the Rx and Tx are bypassed as in the MII stations! *Mobile sets were never designed for this purpose.* If you put a mobile on the air as a station and do not receive or give interference to others, consider yourself lucky. Fred W5VAY Fred missed that this isn't a repeater. But thanks for the reminder Fred. I agree with you on not using mobiles most of the time. For everyone else... I'm sitting here slapping my forehead and saying, Duh. I was (for some unknown reason) trying to do external mix math on the numbers instead of simply subtracting the IF and then dividing... what a maon. Thanks for the (rather obvious now that I see it) help, all. Guess I'll try two things... put the crystals in a station and perhaps with a little better shielding I can lower the effect for now of the mix in the house... short-term, and then order up the high-side injection crystals for the rig and retune when they arrive... Nate WY0X Yahoo! Groups Links
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Nate, I'm wondering if you can point me to a link that would further explain lo / hi injection. Hate to admit, but I'm not all that familiar about the subject, especially in repeater operation. TIA, Don, KD9PT - Original Message - From: Nate Duehr [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Monday, November 27, 2006 6:45 PM Subject: Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio FHS wrote: Users of MII mobiles as repeaters and/or base stations: You should expect interference when you cut corners to save a buck and use a mobile for a repeater. The mobile has no shielding to prevent RF entry or exit, none of the leads are in/out of the Rx and Tx are bypassed as in the MII stations! *Mobile sets were never designed for this purpose.* If you put a mobile on the air as a station and do not receive or give interference to others, consider yourself lucky. Fred W5VAY Fred missed that this isn't a repeater. But thanks for the reminder Fred. I agree with you on not using mobiles most of the time. For everyone else... I'm sitting here slapping my forehead and saying, Duh. I was (for some unknown reason) trying to do external mix math on the numbers instead of simply subtracting the IF and then dividing... what a maon. Thanks for the (rather obvious now that I see it) help, all. Guess I'll try two things... put the crystals in a station and perhaps with a little better shielding I can lower the effect for now of the mix in the house... short-term, and then order up the high-side injection crystals for the rig and retune when they arrive... Nate WY0X Yahoo! Groups Links !DSPAM:1016,456b8b8217055802679531!
Re: [Repeater-Builder] spur from UHF MASTR II mobile - link radio
Don Kupferschmidt wrote: Nate, I'm wondering if you can point me to a link that would further explain lo / hi injection. Hate to admit, but I'm not all that familiar about the subject, especially in repeater operation. TIA, Don, KD9PT Hi Don, Shorty did a nice summary of the low-side/high-side thing -- if you're looking for more information on the design aspects of the receiver itself, probably the best source for that, that includes some background information of how to design a receiver, is the ARRL Handbook. (There's many pages on receiver design, and that section may be a bit dated and seem to apply mostly to HF, but the math and design information still applies to VHF, UHF, etc. It's great background information. I also dug up a couple of links that mention the low-high stuff for you below, but they're not really what I think you might be asking for. It seems your real question might really be, How does a receiver work by using a fixed IF frequency and mixers to detect a signal... Maybe I'm misreading your question and all you needed was the recipe -- Shorty did a very nice job giving you that. If you're looking deeper into the how does that thing work?... that's a bit more in-depth. That question definitely gets further back into receiver design RF engineering basics. And trust me, I'm not an RF engineer, so I won't be embarrassing myself attempting to write that particular article! (GRIN) Being Amateurs, we're all coming from different places in this stuff, and there's folks here on the list who design things like this for a living. Me, I'm a data jockey by day, and RF nerd by night... Trust me, coming from a hobbyist background in this stuff, trudging through an LBI and a schematic can feel like -- even on a relatively old design like the MASTR II -- can feel quite like quick dip in the advanced topics hot-tub! It's all about where you are on the learning curve. http://www.repeater-builder.com/ge/mastrIIsplitconv.html http://www.hallelectronics.com/getech/m2icoms.htm http://www.icmfg.com/generalelectric.html The LBI for the oscillator/multipier board in the receiver also talks about it what's actually going on in the receiver... kinda. You have to apply a bit of knowledge about the design of the receiver itself, which really isn't in the document -- but the document's description is great if you understand how a fairly typical RF receiver works. http://www.repeater-builder.com/ge/lbi-library/lbi-30029j.pdf And of course, the LBI is the critical piece to understanding any GE radio -- it's the document a real engineer wrote for the service techs (and hobbiests!) of the world. And one thing you'll find in an LBI you hardly find anywhere else... an honest to goodness schematic! Find that for an iPod, I dare ya! (GRIN) You can spend hours looking over the circuit at a test point or a specific note from the side-bar figuring out... They say if I put this jumper here, it will do X. Now why is that?! I find it fun -- wish I had more time to do it. Nate WY0X
