RE: [Repeater-Builder] RFS TDE-7780A
Joe, Your screen shots actually prove my point. Both of the pass plots reveal that your duplexer's pass response is far from optimum, which is precisely the reason for selecting the proper duplexer model to tune. If your duplexer was originally designed for operation in the 440-450 MHz band, the peak of the pass plots and the nadir of the notch plots would be exactly 5 MHz apart. Your TX pass plot shows that the peak is about 900 kHz to the left of your desired frequency, and your RX pass plot shows that the peak is off-scale to the right- considerably more than a MHz away from the desired frequency. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Friday, February 05, 2010 6:55 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Eric, I tuned up a 633-6A from a GR-300 recently and got some respectable results. Pass frequency loss was around -1.5dB and notch loss was around -85 to -90dB. I've attached the sweeps. 73, Joe, K1ike Eric Lemmon wrote: Paul, The Motorola TDE7780A duplexer is simply a relabeled Celwave 633-6A-2N unit, and it is designed for 450-470 MHz. It is the standard duplexer furnished in GR300, GR1225, RKR1225, and CDR700 repeaters. The duplexer is okay for non-critical use at low-density RF sites, such as at construction sites. The compact mobile notch design has very little bandpass action, since its operation is based solely upon the notch. I have tried to tune such duplexers down into the Amateur 70cm band, with little success. snip
Re: [Repeater-Builder] RFS TDE-7780A
Correct, but if I remember you were claiming 3dB loss at the pass frequencies. I was seeing about 1.5dB loss. I claimed respectable results, not perfect results. I think it is still acceptable for ham use. Everything is a compromise when you push the equipment past it's limits, but the typical ham is frugal (aka me) and accepts a little degradation for economy. 73, Joe, K1ike Another parsimonious Yankee ham. 73, Joe, K1ike Eric Lemmon wrote: Joe, Your screen shots actually prove my point. Both of the pass plots reveal that your duplexer's pass response is far from optimum, which is precisely the reason for selecting the proper duplexer model to tune. If your duplexer was originally designed for operation in the 440-450 MHz band, the peak of the pass plots and the nadir of the notch plots would be exactly 5 MHz apart. Your TX pass plot shows that the peak is about 900 kHz to the left of your desired frequency, and your RX pass plot shows that the peak is off-scale to the right- considerably more than a MHz away from the desired frequency. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Friday, February 05, 2010 6:55 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Eric, I tuned up a 633-6A from a GR-300 recently and got some respectable results. Pass frequency loss was around -1.5dB and notch loss was around -85 to -90dB. I've attached the sweeps. 73, Joe, K1ike Eric Lemmon wrote: Paul, The Motorola TDE7780A duplexer is simply a relabeled Celwave 633-6A-2N unit, and it is designed for 450-470 MHz. It is the standard duplexer furnished in GR300, GR1225, RKR1225, and CDR700 repeaters. The duplexer is okay for non-critical use at low-density RF sites, such as at construction sites. The compact mobile notch design has very little bandpass action, since its operation is based solely upon the notch. I have tried to tune such duplexers down into the Amateur 70cm band, with little success. snip Yahoo! Groups Links
RE: [Repeater-Builder] RFS TDE-7780A
Point taken. One factor that will directly affect how the subject duplexer will perform at 70cm is where the original factory tuning was. For example, if the factory tuning was in the 450-455 MHz band, such a duplexer will likely perform better at 70cm than will a duplexer that originally was factory-tuned for the 460-465 MHz band. The results I quoted were for a duplexer in the latter class. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Saturday, February 06, 2010 2:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Correct, but if I remember you were claiming 3dB loss at the pass frequencies. I was seeing about 1.5dB loss. I claimed respectable results, not perfect results. I think it is still acceptable for ham use. Everything is a compromise when you push the equipment past its limits, but the typical ham is frugal (aka me) and accepts a little degradation for economy. 73, Joe, K1ike Another parsimonious Yankee ham. 73, Joe, K1ike Eric Lemmon wrote: Joe, Your screen shots actually prove my point. Both of the pass plots reveal that your duplexer's pass response is far from optimum, which is precisely the reason for selecting the proper duplexer model to tune. If your duplexer was originally designed for operation in the 440-450 MHz band, the peak of the pass plots and the nadir of the notch plots would be exactly 5 MHz apart. Your TX pass plot shows that the peak is about 900 kHz to the left of your desired frequency, and your RX pass plot shows that the peak is off-scale to the right- considerably more than a MHz away from the desired frequency. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Joe Sent: Friday, February 05, 2010 6:55 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Eric, I tuned up a 633-6A from a GR-300 recently and got some respectable results. Pass frequency loss was around -1.5dB and notch loss was around -85 to -90dB. I've attached the sweeps. 73, Joe, K1ike Eric Lemmon wrote: Paul, The Motorola TDE7780A duplexer is simply a relabeled Celwave 633-6A-2N unit, and it is designed for 450-470 MHz. It is the standard duplexer furnished in GR300, GR1225, RKR1225, and CDR700 repeaters. The duplexer is okay for non-critical use at low-density RF sites, such as at construction sites. The compact mobile notch design has very little bandpass action, since its operation is based solely upon the notch. I have tried to tune such duplexers down into the Amateur 70cm band, with little success. snip Yahoo! Groups Links
Re: [Repeater-Builder] RFS TDE-7780A
I wonder what they do to the internal coupling at the factory when they tune them. Maybe it is something that can be done in the field with a little surgery? Joe Eric Lemmon wrote: Point taken. One factor that will directly affect how the subject duplexer will perform at 70cm is where the original factory tuning was. For example, if the factory tuning was in the 450-455 MHz band, such a duplexer will likely perform better at 70cm than will a duplexer that originally was factory-tuned for the 460-465 MHz band. The results I quoted were for a duplexer in the latter class. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Saturday, February 06, 2010 2:59 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Correct, but if I remember you were claiming 3dB loss at the pass frequencies. I was seeing about 1.5dB loss. I claimed respectable results, not perfect results. I think it is still acceptable for ham use. Everything is a compromise when you push the equipment past its limits, but the typical ham is frugal (aka me) and accepts a little degradation for economy. 73, Joe, K1ike Another parsimonious Yankee ham. 73, Joe, K1ike
RE: [Repeater-Builder] RFS TDE-7780A
I've disassembled and compared the ham-split PD633-6A-1N and regular 450-470 PD633-6A-2N. The resonators are identical; they're the same length. The difference is where they are tapped - the low-split model is tapped about 1/4 further up the resonator than the 460 MHz version. The semi-rigid interconnect cables are slightly longer on the low-split model as you might expect. I took pictures and started writing it up as an article but never finished... --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Saturday, February 06, 2010 9:45 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A I wonder what they do to the internal coupling at the factory when they tune them. Maybe it is something that can be done in the field with a little surgery? Joe Eric Lemmon wrote: Point taken. One factor that will directly affect how the subject duplexer will perform at 70cm is where the original factory tuning was. For example, if the factory tuning was in the 450-455 MHz band, such a duplexer will likely perform better at 70cm than will a duplexer that originally was factory-tuned for the 460-465 MHz band. The results I quoted were for a duplexer in the latter class. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Joe Sent: Saturday, February 06, 2010 2:59 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Correct, but if I remember you were claiming 3dB loss at the pass frequencies. I was seeing about 1.5dB loss. I claimed respectable results, not perfect results. I think it is still acceptable for ham use. Everything is a compromise when you push the equipment past its limits, but the typical ham is frugal (aka me) and accepts a little degradation for economy. 73, Joe, K1ike Another parsimonious Yankee ham. 73, Joe, K1ike No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.435 / Virus Database: 271.1.1/2640 - Release Date: 02/06/10 07:35:00
RE: [Repeater-Builder] RFS TDE-7780A
Oh, forgot to mention. If you turn your unit upside-down, you should see rubber plugs near the fed ends of each resonator. You can fine-tweak the taps through these holes. It's pretty easy to break a wire, so I wouldn't recommend you go in there and start twistin' and tweakin' with any significant amount of force. Adjusting the distance of the tap wire (center conductor) from the resonator will have a small, but measurable, effect on insertion loss and return loss. 3MB JPEG of a disassembled PD633: http://www.broadsci.com/foo/IMG_6010.jpg 3MB JPEG showing what happens when you mis-tune or over-power one of these duplexers (capacitive loading slug and teflon insulator fried) - they are NOT very forgiving: http://www.broadsci.com/foo/IMG_6031.jpg --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jeff DePolo Sent: Saturday, February 06, 2010 10:55 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] RFS TDE-7780A I've disassembled and compared the ham-split PD633-6A-1N and regular 450-470 PD633-6A-2N. The resonators are identical; they're the same length. The difference is where they are tapped - the low-split model is tapped about 1/4 further up the resonator than the 460 MHz version. The semi-rigid interconnect cables are slightly longer on the low-split model as you might expect. I took pictures and started writing it up as an article but never finished... --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Joe Sent: Saturday, February 06, 2010 9:45 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A I wonder what they do to the internal coupling at the factory when they tune them. Maybe it is something that can be done in the field with a little surgery? Joe Eric Lemmon wrote: Point taken. One factor that will directly affect how the subject duplexer will perform at 70cm is where the original factory tuning was. For example, if the factory tuning was in the 450-455 MHz band, such a duplexer will likely perform better at 70cm than will a duplexer that originally was factory-tuned for the 460-465 MHz band. The results I quoted were for a duplexer in the latter class. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Joe Sent: Saturday, February 06, 2010 2:59 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: [Repeater-Builder] RFS TDE-7780A Correct, but if I remember you were claiming 3dB loss at the pass frequencies. I was seeing about 1.5dB loss. I claimed respectable results, not perfect results. I think it is still acceptable for ham use. Everything is a compromise when you push the equipment past its limits, but the typical ham is frugal (aka me) and accepts a little degradation for economy. 73, Joe, K1ike Another parsimonious Yankee ham. 73, Joe, K1ike No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.435 / Virus Database: 271.1.1/2640 - Release Date: 02/06/10 07:35:00 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.435 / Virus Database: 271.1.1/2640 - Release Date: 02/06/10 07:35:00
RE: [Repeater-Builder] RFS TDE-7780A
At 2/6/2010 20:08, you wrote: Oh, forgot to mention. If you turn your unit upside-down, you should see rubber plugs near the fed ends of each resonator. You can fine-tweak the taps through these holes. It's pretty easy to break a wire, so I wouldn't recommend you go in there and start twistin' and tweakin' with any significant amount of force. Adjusting the distance of the tap wire (center conductor) from the resonator will have a small, but measurable, effect on insertion loss and return loss. 3MB JPEG of a disassembled PD633: http://www.broadsci.com/foo/IMG_6010.jpg Never completely disassembled one, so nice to see what's inside - thanks for posting the nice pic. 3MB JPEG showing what happens when you mis-tune or over-power one of these duplexers (capacitive loading slug and teflon insulator fried) - they are NOT very forgiving: http://www.broadsci.com/foo/IMG_6031.jpg Let me guess: this was removed from the resonator nearest to the TX port. I did this to one years ago, though the damage was not as dramatic. We were increasing the power beyond 50 watts saw something happen at about 80 watts, so we shut down took it out of service immediately. The teflon insulator had arced through the longer thin section looked a lot like the one in your picture, maybe not quite as much charring visible. Fortunately the tuning slug was not damaged. I ended up cleaning out the insulator the best I could swapping it with the one in the TX resonator closest to the antenna port. Most mobile duplexers are rated for 50 watts max. TX power. That rating is quite accurate. Bob NO6B
Re: [Repeater-Builder] RFS TDE-7780A
If that is the former Celwave flat pack duplexer with 6 notch cavites then yes it will work, I have seen many repeaters built with them. I would run no more than 30 watts into them although they are rated for more. I think you are going to make the MVP mad if it gets much use. I think a better platform would be an Exec II. same guts bigger heat sink. If it is a 35 watt radio I would bypass the final transistor by moving the output to the stage before making it a 20 watt radio for the Exec II or consider the stage before that making it a 5 watt radio for the MVP. You are going to need a fan. tom Paul wrote: Okay guys, I am building a tactical, mobile UHF repeater out of a GE MVP and have been looking for a duplexer for the package. I have seen several of the RFS TDE-7780A listed on epay. Do these work reasonably well in the Ham band? My freqs are 445.800 - 440.800. I hope to have 15 to 20 watts out of the MVP after conversion. Two last questions, what cable does the collective recommend for the antenna feedline, between the duplexer and the antenna? Any recommendations for a antenna? The plan is to deploy this repeater when additional radio coverage is needed by placing it on a mountain top or high structure. It would be self contained in an Ammo can or two. Thanks for the input and guidance. Paul KI4ADT Yahoo! Groups Links
RE: [Repeater-Builder] RFS TDE-7780A
Paul, The Motorola TDE7780A duplexer is simply a relabeled Celwave 633-6A-2N unit, and it is designed for 450-470 MHz. It is the standard duplexer furnished in GR300, GR1225, RKR1225, and CDR700 repeaters. The duplexer is okay for non-critical use at low-density RF sites, such as at construction sites. The compact mobile notch design has very little bandpass action, since its operation is based solely upon the notch. I have tried to tune such duplexers down into the Amateur 70cm band, with little success. Although the duplexer APPEARS to tune down just fine, the reality is that the insertion loss begins to climb as the tuning progresses further out of band. For example, one such duplexer had rather impressive numbers at its original frequencies of 451.700/456.700 MHz: insertion loss just under 1.00 dB at the pass frequencies and rejection of greater than 89 dB at the notch frequencies. These numbers are better than Celwave's specs. When I tried re-tuning the same duplexer to the 444/449 MHz band, the insertion losses exceeded 3.0 dB and the rejection notches barely reached 70 dB. These figures were obtained with a calibrated network analyzer. There are folks who will dismiss this poor performance and claim that they have tuned such duplexers into the Amateur 70cm many times, and they always worked fine. Yeah, right. If the application is not critical and mediocre performance is acceptable, go for it. However, for optimum performance in the 70cm band, the Celwave 633-6A-1N duplexer is needed. The difference between the -2N and -1N duplexers involves the size, shape, and position of the internal coupling loops- which are not user-adjustable. The tuning screws are simply variable capacitors that tune the helical resonator coils, while the coupling loops are selected and installed during manufacture based upon the intended band of operation. To test my observations, I bought a Celwave 633-6A-1N duplexer for a portable UHF repeater in the 70cm Amateur band. This duplexer was factory-tuned by Celwave to my coordinated frequencies. I tested the duplexer on my network analyzer, and was pleased to note that its performance was better than Celwave's specs. When combined with a Motorola R1225 full-duplex transceiver in a Pelican case, it makes a very compact, lightweight, and capable repeater for tactical use. The Bottom Line: The TDE7780A duplexer is not a good choice for a 70cm repeater. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Paul Sent: Friday, February 05, 2010 4:10 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] RFS TDE-7780A Okay guys, I am building a tactical, mobile UHF repeater out of a GE MVP and have been looking for a duplexer for the package. I have seen several of the RFS TDE-7780A listed on epay. Do these work reasonably well in the Ham band? My freqs are 445.800 - 440.800. I hope to have 15 to 20 watts out of the MVP after conversion. Two last questions, what cable does the collective recommend for the antenna feedline, between the duplexer and the antenna? Any recommendations for a antenna? The plan is to deploy this repeater when additional radio coverage is needed by placing it on a mountain top or high structure. It would be self contained in an Ammo can or two. Thanks for the input and guidance. Paul KI4ADT
