Re: UHF Repeater Input Frequency Issues
On Thu, Apr 3, 2025 at 01:10 PM, Ralph Mowery wrote:
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Shouldn't the unused ports be terminated with 50 ohms if that is a 50 ohm system ?
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I have not followed the thread all the way but does it have any desense when feeding a dummy load ?
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Ralph ku4pt
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On Thursday, April 3, 2025 at 03:30:17 PM EDT, Jason Weisberger via groups.io <jason@...> wrote:
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On Thu, Apr 3, 2025 at 12:17 PM, Mike wrote:
I'm curious what the 8-way divider was feeding in addition to the DR-2X??
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That 8-way split was integrated into the Sinclair Preamp.? See attached pic.
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We've figured out that the desensing was caused by the duplexer being out of alignment.
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This pictured preamp died in a storm last night causing further issues.? That being said, you're absolutely correct.? An 8 way split is 11dB of loss and that preamp is presumed to be 12dB gain.? I'm probably causing reflections back into the amp without termination of those ports, but the amp is likely doing little good anyway. If we grab another one in the future, it will be 1 port in, 1 port out.
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Great observation, and something I should have caught.
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Re: Where did db Products go?
I think Comscope bought them.
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On Apr 3, 2025, at 6:09?PM, DCFluX via groups.io <dcflux@...> wrote:
? According to a gentleman at the dB Spectra booth at IWCE, it was not them and they are of no relation.
In my research I found conflicting information this past year or more.??? Did db Products get bought by db spectra or Comscope?
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Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
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Re: Where did db Products go?
Commscope owns much of the old DB Products antenna line.?
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Re: F/S TPL PA6-1AE UHF amp
Or 18ft of RG-142 has about 1.5dB loss.?
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Re: Where did db Products go?
According to a gentleman at the dB Spectra booth at IWCE, it was not them and they are of no relation.
In my research I found conflicting information this past year or more.??? Did db Products get bought by db spectra or Comscope?
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Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
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Re: F/S TPL PA6-1AE UHF amp
That's only 1.55dB less than 100w, toss another isolator or filter in line with a lossy jumper and keep the amp.?
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Where did db Products go?
In my research I found conflicting information this past year or more.??? Did db Products get bought by db spectra or Comscope?
--
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Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
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Re: F/S TPL PA6-1AE UHF amp
I am keeping second guessing myself on this. Not sure if I can run 100W for
my coordination so trying to get the amp down to at least 70W out.
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Ken Arck AH6LE via groups.io Sent: Thursday, April 3, 2025 5:43 PM To: [email protected]Subject: Re: [repeater-builder] F/S TPL PA6-1AE UHF amp Really a shame. The TKR-851 will have ZERO issues running at 3 watts to drive that amp. Z-E-R-O Ken At 12:05 PM 4/3/2025, you wrote: Hi all, I'm going to go in a different route with my amplifier so I have this one for sale for 550 shipped.
---------------------------------------------------------------------------- -- President and CTO - Arcom Controllers Makers of repeater controllers and accessories Phone: (503) 678 6182 Authorized Dealers for Kenwood and Telewave. We offer complete turn-key repeater packages! "We don't just make 'em. We use 'em!" []
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Re: F/S TPL PA6-1AE UHF amp
Really a shame. The TKR-851 will have ZERO issues running at 3 watts to drive that amp. Z-E-R-O Ken At 12:05 PM 4/3/2025, you wrote: Hi all, I'm going to go in a different route with my amplifier so I have this one for sale for 550 shipped.
------------------------------------------------------------------------------ President and CTO - Arcom Controllers Makers of repeater controllers and accessories Phone: (503) 678 6182 Authorized Dealers for Kenwood and Telewave. We offer complete turn-key repeater packages! "We don't just make 'em. We use 'em!" []
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Re: F/S TPL PA6-1AE UHF amp
Hi,
I can get some pics this evening.
Thanks
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Kory Oldham W4RZ Sent: Thursday, April 3, 2025 5:35 PM To: [email protected]Subject: Re: [repeater-builder] F/S TPL PA6-1AE UHF amp Chad, Do you have any pictures of the amp? You can email me directly if you prefer. Kory W4RZ (good on QRZ) On 2025-04-03 15:05, Chad Nelson wrote: Hi all, I'm going to go in a different route with my amplifier so I
have this one for sale for 550 shipped.
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Check out Fairview Microwave's website (link below),? I am not sure exactly what size you need (i missed that somewhere), but they have a wide variety.?
Kory
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On 2025-04-02 23:37, M M via groups.io wrote:
An attenuator something like this one may be easier....?? use your
existing 5w input amp...
I have no idea who this guy is, I'm just using his auction as an
example.?? But $27 and free shipping?
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Decades ago I saw an attenuator between an exciter and an amplifier...
it was a (roughly) 100 foot coil of RG58....? Please don't do that.
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Mike WA6ILQ
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Re: F/S TPL PA6-1AE UHF amp
Chad,
Do you have any pictures of the amp? You can email me directly if you prefer.
Kory
W4RZ (good on QRZ)
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On 2025-04-03 15:05, Chad Nelson wrote: Hi all, I'm going to go in a different route with my amplifier so I have this one for sale for 550 shipped.
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Re: UHF Repeater Input Frequency Issues
Shouldn't the unused ports be terminated with 50 ohms if that is a 50 ohm system ?
I have not followed the thread all the way but does it have any desense when feeding a dummy load ?
Ralph ku4pt
On Thursday, April 3, 2025 at 03:30:17 PM EDT, Jason Weisberger via groups.io <jason@...> wrote:
On Thu, Apr 3, 2025 at 12:17 PM, Mike wrote:
I'm curious what the 8-way divider was feeding in addition to the DR-2X??
?
That 8-way split was integrated into the Sinclair Preamp.? See attached pic.
?
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Re: UHF Repeater Input Frequency Issues
Jason
Just curious, why do you have an eight way splitter in line to the receiver. The preamp is there to offset the loss in the splitter. Try eliminating both, but not the preselector.
Charles Adams
Industrial Communications Co.
Mobile 610-360-0050?
Office 610-253-1214?
cadams@...
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On Thu, Apr 3, 2025 at 12:17 PM, Mike wrote:
I'm curious what the 8-way divider was feeding in addition to the DR-2X??
?
That 8-way split was integrated into the Sinclair Preamp.? See attached pic.
?
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Re: UHF Repeater Input Frequency Issues
On Thu, Apr 3, 2025 at 12:17 PM, Mike wrote:
I'm curious what the 8-way divider was feeding in addition to the DR-2X??
?
That 8-way split was integrated into the Sinclair Preamp.? See attached pic.
?
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Re: UHF Repeater Input Frequency Issues
I'm curious what the 8-way divider was feeding in addition to the DR-2X??
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Hi all, I'm going to go in a different route with my amplifier so I have this one for sale for 550 shipped.
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Re: UHF Repeater Input Frequency Issues
Update:? It was the duplexer being misaligned.? Also, the preamp must have taken a surge, because it's also dead as of yesterday afternoon.
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Also, we found a 30dB notch filter laying around and tuned and added it to the input.? We then flipped the amp back on.... still no dice, but it did clean up the input nicely so we likely won't need a preamp going forward.? 20W will have to do for now.? Will investigate adding a better duplexer.
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@Chris Boone WB5ITT
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I'm going to message you directly about that duplexer you mentioned.
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Re: UHF Repeater Input Frequency Issues
The Yaesu DR-2X has no front end filtering to speak of and relies completely on the duplexer and other front end filtering to survive. I had one on a perfectly tuned 4 can Motorola 1500 series Bp/Br duplexer (85dB isolation) with 85w amp and it was not happy with noticeable desense. I replaced the duplexer with a Celwave PD526 series six cavity 120dB isolation and it finally plays nice. I also found my 5w input amp fed by the DR-2X at 5w had all kinds of spurious crap coming out of the DR-2X transmitter but the DR-2X was fairly clean at 20w so I use the repeater at 20w with a 6dB attenuator into the amp for 85w out and that is working ok.?
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If you have a certain amount of isolation in the duplexer, adding a preamp with no preselector filter will roughly reduce the amount of duplexer isolation by the amount of gain the preamp has by amplifying transmitter noise. Plus you may be hitting the preamp with enough out of band energy to create IMD which can raise the noise floor or produce ghost signals that may land on your repeater input frequency. I would suggest looking at the output of the existing amplified 8-way divider with a good spectrum analyzer to see what the repeater receiver is seeing when running at 100w. Is the desense due to increased noise floor or is there an actual signal present on the input only when the repeater is transmitting, etc? If so you can start removing things to see what affects the desense like remove the preamp and connect the repeater receiver right to the duplexer and see if the desense is reduced or eliminated. I see you have run the repeater at 20w without the power amp and desense is reduced but you need to know why its better.?
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I suspect the main problem is the duplexer does not have enough isolation and using a preamp without an adequate cavity filter in front of the preamp is degrading isolation and the power amp is adding to the problem. A better duplexer and an adequate preselector filter ahead of the preamp with amp running at 250w in the future might all work together but maybe not with a DR-2X but might with a commercial quality repeater.
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When you say the input goes away when it rains or snows are you talking about the receiver input as in it doesn't receive at all during rain or snow? If so to what extent? Just weak distant signals or from a radio transmitting right at the repeater site? How bout a service monitor right into the duplexer or repeater receiver? This sounds like a separate problem needing more info.?
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Re: UHF Repeater Input Frequency Issues
Also I'd ditch the preamp...
Chris WB5ITT
UPDATE:? Connecting the feedline directly to an HT and removing the repeater, preamp and duplexer yields a great simplex signal in both directions.?
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So...... Duplexer, preamp or repeater I'm assuming.
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Karl Shoemaker
Ken Arck AH6LE
Chris Boone WB5ITT