Re: [Repeater-Builder] Re: Sinclair Q 202G Tuning Problem
Does this mean that this vintage of the Q-202G's are only capable of working at one insertion loss point for any given offset? 73 Paul - Original Message - From: Harold Farrenkopf Rotating the loop would change the insertion loss and the pass to reject spacing. 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] Re: Sinclair Q 202G Tuning Problem
The loops can be rotated a slight amount, as they are mounted in round holes on top of the vertical cavities with the notch tuning rods extending horizontally from the loop assembly. Three screws clamp the assembly to the can. The rods would interfere with the cavity beside it if rotated more than 5 degrees or so. I suppose the internal loop could be bent or twisted to space it away from the internal quarter wave as the whole assembly lifts right out of the cavity when you remove the screws. I measured the jumper cables end to end including the connectors (10.5 inches) and also measured the two new cables I made (12.5 inches) the same way. Tinkering with the capacitance would sure be a lot more trouble than rebuilding the cables I think, so this was definitely the right way to modify the 170 meg duplexer down to 147 meg. If the whole harness assembly is still available from Sinclair then Eric (WB6FLY) had the right idea to just replace the whole thing. Just buying a couple of cables would cost $50 or so, and the whole assembly at $150 would be a bargain. 73 - Jim W5ZIT That was suppose to be 10.5 of cable before the N male connectors are put on. Adding the connectors adds more length to the assembly. Where did you measure the 10.5 of cable? Rg214/u or Rg213/u both have the same velocity factor so the lengths would be the same. Can't remember if the loops on that configuration were rotatable. Rotating the loop would change the insertion loss and the pass to reject spacing. There are several variables that effect the overall response. Harold Does this mean that this vintage of the Q-202G's are only capable of working at one insertion loss point for any given offset? 73 Paul 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/
[Repeater-Builder] Re: Sinclair Q 202G Tuning Problem
The side mounted loop stub Q202s had different loops based on frequency and spacings for a given a given isolation. Most cavities were designed for 0.6dB Insertion Loss so 4 cans produced 1.5dB or less per side. You could distort it to change the insertion loss. You can rotate the loops on the top mounted cans for both the stub and capacitor types of Q cavities to change the insertion loss and notch depth but you should have the proper test equipment to see the effects of those changes. Distorting the loop will also affect the can's insertion loss and notch depth and locations. Opening up the loop to have more area inside or rotating the loop so that it becomes more in line with the radial line out from the center gives the cavity less insertion loss but when the notch is adjusted for the desired separation, the notch depth is less and it becomes narrower. The notch might not come in close enough either. Conversely, if the loop is squished smaller or rotated away from the radial line, the insertion loss increases at the pass frequency and the notches move closer to the pass. Adjusting the notch to the desired spacing will produce a deeper wider notch than before. Doing this to a duplexer, improves the midband isolation between the TX and RX ports. Note, when a loop is rotated or distorted, the pass frequency of the cavity will move and will have to be adjusted before adjusting the notch frequency. You should not distort the loop of a loop with a capacitor since they are extremely fragile and will break if there is force applied. Also, soldering the loop on the capacitors is tricky as well and must be done quickly and so that it doesn't unsolder apart. Harold --- In Repeater-Builder@yahoogroups.com, Paul Holm [EMAIL PROTECTED] wrote: Does this mean that this vintage of the Q-202G's are only capable of working at one insertion loss point for any given offset? 73 Paul - Original Message - From: Harold Farrenkopf Rotating the loop would change the insertion loss and the pass to reject spacing. 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/
[Repeater-Builder] Re: Sinclair Q 202G Tuning Problem
Is it a top mounted loop or side mounted loop on the cavity? Changing the loop shape can also pull in the notch closer to the pass frequency. Changing its length also has an effect on insertion loss, coupling and the pass to notch spacing. A network analyser becomes very useful in determining what effect you are having when modifying the loops. Are the 8 cables individually connectorized? Maybe a photo would help. I have seen many versions made by Sinclair and they were built with stubs to the mid 70s. Too bad Jim Morrison retired. After that, the company's help dissappeared. It returned for about a year (2000/2001) when I breifly returned and knew where all the old docs were. Harold --- In Repeater-Builder@yahoogroups.com, Jim Brown [EMAIL PROTECTED] wrote: If the tunable stub is connectorized, then just add a 90 degree connector in line to make it a bit longer. No connectors on the tuning stub. The coupling loop is built into the stub and it extends at a right angle from the loop insert. A single N connector opposite the tuning stub couples to the harness. I am not sure if the center conductor inside the notch tube will unscrew from the connector/loop assembly. It looks like it is soldered to the loop and connector. It depends on the version of the old stub Q202 duplexer you have. Is it side mounted or top mounted loops and are there 4 or 8 pieces of coax being used? Is the harness connectorized with separate Ts or is it one assembly? The coax lengths should be a little longer but I think 2 is too much if I remember correctly. You should still be able to make it work with that cable harness. The harness is made up of 8 individual cables with all cables the same length except for one that couples from the junction of the antenna output cable and the receiver connection. (transmitter connection is also longer). I have tried extending the cables with an elbow connector on each of the cavities that won't tune with no change in the tuning characteristics. A good working stub Q202 is better than a new Q202 with capacitor loops. Harold, VA3HF --- In Repeater-Builder@yahoogroups.com, Burt Lang burt@ wrote: What you are experiencing is the symptioms of insufficient capacity to pull the notch down low enough on the low pass side. The capacity range of those tuning stubs is determined by the length of the center rod inside the plastic stub. They are 3/16 (I think) diameter brass rod with a threaded end. Sinclair had several lengths available, the longest one being about 6in long. There is probably nobody left at Sinclair that even remembers that part as that design dates back to the 1950s or 60s and was superseded by the Johanson trimmer design in the late 1960s. You should be able to get a local machinist to make you a longer one using the one you have as an example. Burt VE2BMQ Thanks for the inputs - 73 - Jim - W5ZIT 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/
[Repeater-Builder] Re: Sinclair Q 202G Tuning Problem
According to the information I have, all the cables between the T's should be the same length. For the VHF ham band, the cut length of RG214/u should be 10.5 long then trim to add the N male connectors without making it shorter. Was your duplexer top or side mounted loops? If they are the side mounted type with the spun cavities (non welded top type) there may be higher insertion losses due to the oxidation of the mating junction of the resonator to the can. To resolve this problem I usually loosen the 6 bolts that hold the resonator to the can and clean the contact surfaces by just mechanically rubbing the two surfaces together. To do it properly, the cans have to be disassembled which is allot of work. The resonator invar rod tunes the pass freguencies and the stubs tune the reject frequencies. Harold --- In Repeater-Builder@yahoogroups.com, Jim Brown [EMAIL PROTECTED] wrote: Jim - W5ZIT wrote: I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz range and have run into a problem on the notch tuning. The high pass tuning works like a charm and has a good pass and notch characteristic. The low pass side is another story. The pass tuning works fine, but I can't get a notch. With the tuning rods all the way in, it is starting to notch, but only about 20 db. Eric - WB5FLY wrote: Jim, Sinclair makes two harness assemblies for that duplexer. The jumpers are about two inches longer in the low-range harness, and that makes a world of difference. You can order the low-split harness directly from Sinclair. Go to: www.sinctech.com Make it very clear that you want the low range harness, as some of the Sinclair sales folk seemed to be unaware of its availability, the last time I called them. A year or so ago, that harness cost about $145. It's all in one piece, with crimped connections. As I recall, the low range was for 136-150 MHz, and the high range was for 150-174 MHz. Most Bp/Br cavities will have one notch above and one notch below the pass frequency. I have tuned several Sinclair duplexers of this design, and they all tuned up perfectly once the correct harness was installed. 73, Eric Lemmon WB6FLY Eric - I took your advice and built up a couple of jumpers to go from the cans back to the tee in the harness on the low pass side and made them 2 inches longer than the old ones as you suggested and presto - nice deep null with the tuning rods. Thanks to all for the feedback, and thanks to the list for helping to solve this problem. 73 - Jim W5ZIT 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] Re: Sinclair Q 202G Tuning Problem
Harold, the cavities are the welded type and the loops penetrate the top. The cavities have an extra hole on the other side so a band pass coupling system with an input and an output loop could be used. But the hole on the opposite side is covered with a plug, and only one connector/capacitor stub is used per cavity. The capacitor stub extends away from the cavity at right angles across but not touching the adjacent cavity. The original cables were the 10.5 inch dimension that you mention, and I wound up with 12.5 inch cables to make it work. I suspect 12 inches even would work as well as there is some room left on the rods to do some more tuning. The cables were RG-213, by the way - I just left the high-pass side of the duplexer alone since it tuned up just fine with the 10.5 inch cables. So just modified the low-pass side cables to make it work on 147.76/147.16. Thanks again for the help and comments. 73 - Jim W5ZIT According to the information I have, all the cables between the T's should be the same length. For the VHF ham band, the cut length of RG214/u should be 10.5 long then trim to add the N male connectors without making it shorter. Was your duplexer top or side mounted loops? If they are the side mounted type with the spun cavities (non welded top type) there may be higher insertion losses due to the oxidation of the mating junction of the resonator to the can. To resolve this problem I usually loosen the 6 bolts that hold the resonator to the can and clean the contact surfaces by just mechanically rubbing the two surfaces together. To do it properly, the cans have to be disassembled which is allot of work. The resonator invar rod tunes the pass freguencies and the stubs tune the reject frequencies. Harold --- In Repeater-Builder@yahoogroups.com, Jim Brown [EMAIL PROTECTED] wrote: Jim - W5ZIT wrote: I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz range and have run into a problem on the notch tuning. The high pass tuning works like a charm and has a good pass and notch characteristic. The low pass side is another story. The pass tuning works fine, but I can't get a notch. With the tuning rods all the way in, it is starting to notch, but only about 20 db. Eric - WB5FLY wrote: Jim, Sinclair makes two harness assemblies for that duplexer. The jumpers are about two inches longer in the low-range harness, and that makes a world of difference. You can order the low-split harness directly from Sinclair. Go to: www.sinctech.com Make it very clear that you want the low range harness, as some of the Sinclair sales folk seemed to be unaware of its availability, the last time I called them. A year or so ago, that harness cost about $145. It's all in one piece, with crimped connections. As I recall, the low range was for 136-150 MHz, and the high range was for 150-174 MHz. Most Bp/Br cavities will have one notch above and one notch below the pass frequency. I have tuned several Sinclair duplexers of this design, and they all tuned up perfectly once the correct harness was installed. 73, Eric Lemmon WB6FLY Eric - I took your advice and built up a couple of jumpers to go from the cans back to the tee in the harness on the low pass side and made them 2 inches longer than the old ones as you suggested and presto - nice deep null with the tuning rods. Thanks to all for the feedback, and thanks to the list for helping to solve this problem. 73 - Jim W5ZIT 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/
[Repeater-Builder] Re: Sinclair Q 202G Tuning Problem
That was suppose to be 10.5 of cable before the N male connectors are put on. Adding the connectors adds more length to the assembly. Where did you measure the 10.5 of cable? Rg214/u or Rg213/u both have the same velocity factor so the lengths would be the same. Can't remember if the loops on that configuration were rotatable. Rotating the loop would change the insertion loss and the pass to reject spacing. There are several variables that effect the overall response. Harold Harold --- In Repeater-Builder@yahoogroups.com, Jim Brown [EMAIL PROTECTED] wrote: Harold, the cavities are the welded type and the loops penetrate the top. The cavities have an extra hole on the other side so a band pass coupling system with an input and an output loop could be used. But the hole on the opposite side is covered with a plug, and only one connector/capacitor stub is used per cavity. The capacitor stub extends away from the cavity at right angles across but not touching the adjacent cavity. The original cables were the 10.5 inch dimension that you mention, and I wound up with 12.5 inch cables to make it work. I suspect 12 inches even would work as well as there is some room left on the rods to do some more tuning. The cables were RG-213, by the way - I just left the high-pass side of the duplexer alone since it tuned up just fine with the 10.5 inch cables. So just modified the low-pass side cables to make it work on 147.76/147.16. Thanks again for the help and comments. 73 - Jim W5ZIT According to the information I have, all the cables between the T's should be the same length. For the VHF ham band, the cut length of RG214/u should be 10.5 long then trim to add the N male connectors without making it shorter. Was your duplexer top or side mounted loops? If they are the side mounted type with the spun cavities (non welded top type) there may be higher insertion losses due to the oxidation of the mating junction of the resonator to the can. To resolve this problem I usually loosen the 6 bolts that hold the resonator to the can and clean the contact surfaces by just mechanically rubbing the two surfaces together. To do it properly, the cans have to be disassembled which is allot of work. The resonator invar rod tunes the pass freguencies and the stubs tune the reject frequencies. Harold --- In Repeater-Builder@yahoogroups.com, Jim Brown w5zit@ wrote: Jim - W5ZIT wrote: I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz range and have run into a problem on the notch tuning. The high pass tuning works like a charm and has a good pass and notch characteristic. The low pass side is another story. The pass tuning works fine, but I can't get a notch. With the tuning rods all the way in, it is starting to notch, but only about 20 db. Eric - WB5FLY wrote: Jim, Sinclair makes two harness assemblies for that duplexer. The jumpers are about two inches longer in the low-range harness, and that makes a world of difference. You can order the low-split harness directly from Sinclair. Go to: www.sinctech.com Make it very clear that you want the low range harness, as some of the Sinclair sales folk seemed to be unaware of its availability, the last time I called them. A year or so ago, that harness cost about $145. It's all in one piece, with crimped connections. As I recall, the low range was for 136-150 MHz, and the high range was for 150-174 MHz. Most Bp/Br cavities will have one notch above and one notch below the pass frequency. I have tuned several Sinclair duplexers of this design, and they all tuned up perfectly once the correct harness was installed. 73, Eric Lemmon WB6FLY Eric - I took your advice and built up a couple of jumpers to go from the cans back to the tee in the harness on the low pass side and made them 2 inches longer than the old ones as you suggested and presto - nice deep null with the tuning rods. Thanks to all for the feedback, and thanks to the list for helping to solve this problem. 73 - Jim W5ZIT 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/
[Repeater-Builder] Re: Sinclair Q 202G Tuning Problem
If the tunable stub is connectorized, then just add a 90 degree connector in line to make it a bit longer. It depends on the version of the old stub Q202 duplexer you have. Is it side mounted or top mounted loops and are there 4 or 8 pieces of coax being used? Is the harness connectorized with separate Ts or is it one assembly? The coax lengths should be a little longer but I think 2 is too much if I remember correctly. You should still be able to make it work with that cable harness. A good working stub Q202 is better than a new Q202 with capacitor loops. Harold, VA3HF --- In Repeater-Builder@yahoogroups.com, Burt Lang [EMAIL PROTECTED] wrote: What you are experiencing is the symptioms of insufficient capacity to pull the notch down low enough on the low pass side. The capacity range of those tuning stubs is determined by the length of the center rod inside the plastic stub. They are 3/16 (I think) diameter brass rod with a threaded end. Sinclair had several lengths available, the longest one being about 6in long. There is probably nobody left at Sinclair that even remembers that part as that design dates back to the 1950s or 60s and was superseded by the Johanson trimmer design in the late 1960s. You should be able to get a local machinist to make you a longer one using the one you have as an example. Burt VE2BMQ Jim Brown wrote: I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz range and have run into a problem on the notch tuning. The high pass tuning works like a charm and has a good pass and notch characteristic. The low pass side is another story. The pass tuning works fine, but I can't get a notch. With the tuning rods all the way in, it is starting to notch, but only about 20 db. Here is the strange thing - I took the coupling loop out of the high pass side and compared it to the low pass side, and they are identical. The tuning rod varies the capacitance across the single loop connector and there is no inductance in the circuit for either high pass or low pass side. How does the same hookup work to allow a notch on the low side as well as the high side? I am tempted to add a small fixed capacitance across the loop to see if that helps the tuning for the low pass side.. Any comments on which way to go? 73 - Jim W5ZIT 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] Re: Sinclair Q 202G Tuning Problem
If the tunable stub is connectorized, then just add a 90 degree connector in line to make it a bit longer. No connectors on the tuning stub. The coupling loop is built into the stub and it extends at a right angle from the loop insert. A single N connector opposite the tuning stub couples to the harness. I am not sure if the center conductor inside the notch tube will unscrew from the connector/loop assembly. It looks like it is soldered to the loop and connector. It depends on the version of the old stub Q202 duplexer you have. Is it side mounted or top mounted loops and are there 4 or 8 pieces of coax being used? Is the harness connectorized with separate Ts or is it one assembly? The coax lengths should be a little longer but I think 2 is too much if I remember correctly. You should still be able to make it work with that cable harness. The harness is made up of 8 individual cables with all cables the same length except for one that couples from the junction of the antenna output cable and the receiver connection. (transmitter connection is also longer). I have tried extending the cables with an elbow connector on each of the cavities that won't tune with no change in the tuning characteristics. A good working stub Q202 is better than a new Q202 with capacitor loops. Harold, VA3HF --- In Repeater-Builder@yahoogroups.com, Burt Lang [EMAIL PROTECTED] wrote: What you are experiencing is the symptioms of insufficient capacity to pull the notch down low enough on the low pass side. The capacity range of those tuning stubs is determined by the length of the center rod inside the plastic stub. They are 3/16 (I think) diameter brass rod with a threaded end. Sinclair had several lengths available, the longest one being about 6in long. There is probably nobody left at Sinclair that even remembers that part as that design dates back to the 1950s or 60s and was superseded by the Johanson trimmer design in the late 1960s. You should be able to get a local machinist to make you a longer one using the one you have as an example. Burt VE2BMQ Thanks for the inputs - 73 - Jim - W5ZIT 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/
