UPMAN HELP BNC T hooked to 996p2 and sds100

[SCPD]

So i was brainwashed into going to the local ham store and buying a BNC T today. I hooked it up in place of my multicoupler that works fine with all 5 of my other scanners...


To the point...
in the beta forum i was instructed to use a BNC T instead of a multicoupler to see if the vhf signal bleed was from my multicoupler...

So antenna to BNC T then coax from BNC directy to sds100 and other end of BNC T directly to my bcd996p2.


The 996P2 still recieves like brand new...

However the sds100 since being recommended by someone in forums to hook 2 scanners to a BNC T no longer even receives the local weather that used to ghost over to the whole vhf high band and overload only vhf hi band... now even my UHF chnnels do not come in...

Why should I have to pay as the repair person said on the phone because its an unisolated BNC connection that burned it out?

I believe the ONE who recommended this action as a Uniden Fan should pay for this repair as he stated to do this and blamed the multicoupler..

Is this true that hooking 2 scanners through a BNC T will do as uniden tech said and burn out the scanner as someone recommended I needed to do in the public forum for the sds 1.05.00 open beta.. Unfortunately most of that conversation was blown out of proportion and deleted by admins..

How can this be fixed?

 

[scosgt]

Good luck getting some guy on some forum to pay for your repair.

 

[mule1075]

I believe the ONE who recommended this action as a Uniden Fan should pay for this repair as he stated to do this and blamed the multicoupler

Good luck with that. You took the advice so really the only one you should be blaming is you.

 

[SCPD]

Good luck getting some guy on some forum to pay for your repair.

Has anyone else heard of successfully hooking 2 scanners up this way with a BNC T? or is the tech correct that the 2 unisolated ports on the bnc T burnt the receiver out? I'm only curious cause the said person does seem to give alot of what I thought was helpful advice.

 

[SCPD]

Good luck getting some guy on some forum to pay for your repair.

Then he should be banned from posting help ever again... Atleast

 

[RRR]

How can one receiver burn out another receiver, if coupled together, and aren't outputting anything?

 

[SCPD]

How can one receiver burn out another receiver, if coupled together, and aren't outputting anything?

Accourding to the uniden tech there is energy stored in the capacitors along the receive end.. And yes they do emit a small Amount of VDC which when hooked together can cancel out one another and in this case Burn out the new receive design. By default theres supposed to be a diode in place for overcurrect from stuff like this

 

[sibbley]

I reported the post and was issued an warning because i reported the guy.. Im also fan of Uniden as well but i do not go around telling people hook up scanners in a way that will burn them up..

Has anyone else heard of successfully hooking 2 scanners up this way with a BNC T? or is the tech correct that the 2 unisolated ports on the bnc T burnt the receiver out? I'm only curious cause the said person does seem to give alot of what I thought was helpful advice.

I used a BNC T for almost a year in my vehicle till I bought an active multicoupler. I never had any issue with burning up a scanner using a BNC T. I don't think the "T" had anything to do with your problem.

Did the SDS just stop receiving? Mine is at repair now because it simply went deaf. It received in at night and I had nothing the next morning when I turned it on. Not even the national weather service.

I never used a "T" with the SDS though.

 

[jonwienke]

Also you can damage the receivepreamp and protection DIODES by backfeeding vdc from 1 scanner to another... Give facts instead of trying to Burn out peoples scanners that alot of people work sun up to sun down to buy...

Absolutely let's stick to facts.

It's pretty easy to verify that Uniden scanners don't output a DC voltage at the antenna connector; a simple DC volt meter or oscilloscope is all that's required. No current Uniden scanner has a built-in bias-T for powering an external preamp. If they did, you couldn't use antennas with impedance matching transformers or other designs like J-poles that are short circuits to DC voltages without inserting a compatible preamp between the scanner and antenna. So that's an easily disproven non-fact.

While RFI from the local oscillator can be output from the antenna connector, if the RFI was powerful enough to fry the protection diodes in a second radio connected with a T connector, it would also fry the radio originating the RFI and/or overload both radios the the point of total non-reception.

Fun fact: when checking the antennas in my vehicle for cross-coupling, I measured 250mW of RF feeding into the scanner antenna when I keyed up a VHF radio connected to a different antenna. I've keyed up that radio with scanners connected (hitting their antenna connector with the aforementioned 250mW of VHF RF) on many occasions, with no detectable damage or loss of sensitivity to my 536, 436, or SDS100. I've also connected the same RF power meter to the antenna connector on my 536, 436, and SDS100 when they were turned on and scanning, and was not able to get a reading distinguishable from zero under any circumstance.

So while it's possible for RFI from one scanner to cause a birdie in another scanner when their antenna ports are connected together with a T, the RF level feeding from one radio to the other under normal operation is numerous orders of magnitude below the threshold that could potentially cause any damage, at least with the SDS100, 436, and 536.

Claiming that one scanner may interfere with another when connected together with a non-isolated T is possible, but in most cases (at least with the 536, 436, and SDS100 that I've tested) it's not a common issue.

Claiming that 2 scanners will fry each others' protection diodes or first-stage RF amplifier transistors if their antenna ports are connected together with a non-isolated T is absurd.

 

[UPMan]

If Gabriel said that, he was mistaken. I can't check with him, as he has been gone for 3 or 4 years.

I commonly also connect multiple scanners to the same antenna using T connectors. Never had an issue. In theory, you could get some conducted IF between the scanners that could cause some interference (but not damage), but I've never actually experienced that.

Now, connecting a transmitter and scanner to the same antenna using a T-adapter would be an entirely different story. You would quickly let the magic smoke out of the scanner.

 

[wx5uif]

I just got my SDS100 back from repair where it stopped receiving. I don't know if the new design is more static sensitive or what.

Q1, Q2 were replaced. Just taking a guess that those are the first two transistors in the signal path.

 

[lou9155]

can you send it in under warranty

 

[iMONITOR]

Have you tried the SDS100 using nothing but the stock antenna? If it still doesn't work, might it be possible that the antenna adapters used may have physically/mechanically damaged the antenna connector? Try using a short piece of wire and touch the center pin of the antenna connector and see if that works (being careful of static electricity of course, which shouldn't be a problem this time of year).


DISCLAIMER

 

[scosgt]

This thread is nutty.
OP sounds 12 years old, wants somebody someplace to pay for repairs that did not even result from the advice he took.

 

[pb_lonny]

This reminds me of the YouTube video, showing people how to drill a hole in a brand new iPhone to add a 3.5mm audio jack.

Just because somebody on the Internet tells you to do something, does not mean you should...

 

[jonwienke]

The advice I gave was sound, and had nothing to do with any damage the OP's scanner may or may not have suffered, as confirmed by Upman. There's no way the scanner could have been examined by a Uniden technician already, and I'm not aware of any direct line to talk to a Uniden repair tech on the phone that is available to the general public. So I'm skeptical of the claim the OP spoke to a Uniden technician who diagnosed his scanner problem over the phone. Which is doubly unlikely since that sort of thing generally required physical access to the device to run diagnostic tests, not just a phone conversation.

 

[pb_lonny]

The advice I gave was sound, and had nothing to do with any damage the OP's scanner may or may not have suffered, as confirmed by Upman.

So either his radio has an issue (warranty?) or he has done something wrong. I never thought for a second what you suggested would cause any damage.

 

[fxdscon]

I'm not aware of any direct line to talk to a Uniden repair tech on the phone that is available to the general public. So I'm skeptical of the claim the OP spoke to a Uniden technician who diagnosed his scanner problem over the phone.

His whole story seemed very suspicious from the start. In one of his posts from the other thread (which was subsequently deleted when the mods cleaned up that thread) he stated that he spoke with the tech at Uniden this morning named Gabriel. We see in UPMan’s post up above that Gabriel hasn’t been at Uniden for 3-4 years.

.

 

[captainmax1]

I have used a BNC T-Splitter for 40 years in my vehicle and home without incident to any scanners. I used my 436 & SDS100 on a BNC T-Splitter in my bedroom and vehicle nearly 24/7 when I first received my SDS100 until I received my second multicoupler a month later. My other multicoupler is installed in my office/radio shack/music lab. I never attach one end of a T-Splitter directly to the scanner antenna connection because of possible pressure damage to connection but instead use 2 jumper cables from each scanner to the T-Splitter. The only downfall I ever thought from using a T would be a weakened signal to the scanners but it never was noticeable. This is my experience with the T-Splitter.

 

[jonwienke]

His whole story seemed very suspicious from the start. In one of his posts from the other thread (which was subsequently deleted when the mods cleaned up that thread) he stated that he spoke with the tech at Uniden this morning named Gabriel. We see in UPMan’s post up above that Gabriel hasn’t been at Uniden for 3-4 years.

Well, there you go. The whole thing seems to be very odd, and at least partly a personal attack directed toward me. And I was trying to help the guy, even if he doesn't understand or appreciate it. It's a good thing my self-esteem is not founded on whether every random stranger I meet on the internet likes me.

Fortunately for the OP, his scanner is still under warranty, and I can't imagine Uniden expecting him to pay for the repair if UPMan confirms that it's totally safe to connect 2 scanners to the same antenna with a T connector.