• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.
  • Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

    We've noticed a huge increase in rants and negative posts that revolve around agencies going to encryption due to the broadcasting of scanner audio on the internet. It's now worn out and continues to be the same recycled rants. These rants hijack the threads and derail the conversation. They no longer have a place anywhere on this forum other than in the designated threads in the Rants forum in the Tavern.

    If you violate these guidelines your post will be deleted without notice and an infraction will be issued. We are not against discussion of this issue. You just need to do it in the right place. For example:
    https://forums.radioreference.com/rants/224104-official-thread-live-audio-feeds-scanners-wait-encryption.html

TK5710-K speaker bias

Status
Not open for further replies.

N5APC

Member
Premium Subscriber
Joined
Jan 18, 2016
Messages
3
Location
Buchanan Dam, TX
Our FD runs several TK5710-k in trunking mode. Within the last two months, we have experienced speaker failure on two units. The speaker lines have 6 volts across them causing the speaker to become hot and fail.
The first failure was in a unit that was due to be replaced soon so we did a work around with an electrolytic cap in the line. The second unit to fail is in the station on an AC PS. These units have been in service for a couple of years with no incidents and then 2 identical failures within a few weeks.

Just curious if anyone else has experienced similar failures.

73's
Mike
 

RFI-EMI-GUY

Member
Joined
Dec 22, 2013
Messages
3,080
Our FD runs several TK5710-k in trunking mode. Within the last two months, we have experienced speaker failure on two units. The speaker lines have 6 volts across them causing the speaker to become hot and fail.
The first failure was in a unit that was due to be replaced soon so we did a work around with an electrolytic cap in the line. The second unit to fail is in the station on an AC PS. These units have been in service for a couple of years with no incidents and then 2 identical failures within a few weeks.

Just curious if anyone else has experienced similar failures.

73's
Mike
See below, this radio, like most these days has a BTL audio amplifier. If one side of the speaker line is inadvertently grounded it can damage the amplifier and/or speaker. Check the installation to make sure the proper speakers were installed and that no other equipment has been installed on the speaker lines. It is common in fire trucks to have an intercom system wired to the radio, and in fire stations to have a PA system wired in. For these custom installations, a transformer should be used to isolate the radios amplifier from the load.


---------

8. External Speaker (KES-5/6:Option)
The speaker output from the transceiver is as follows:
1. The KCH-14 has a built-in speaker (3W/8 ohms).
2. The KCH-15 does not have a built-in speaker.
3.The external speaker output from the accessory
connector (9-pin) on the rear of the transceiver is 13W/4
ohms. Use the KES-5 or KES-6.
4.The speaker output from the accessory connector (12-
pin) on the rear of the control head is 2W/4 ohms. If the
remote kit (KRK-5, KRK-6DH) is used, use the KES-5 or
KES-6.
Note :
Since the transceiver uses a BTL audio amplifier, do not
ground the speaker output

------

BTL is an acronym for "bridge-tied load." A bridge-tied load configuration consists of one amplifier driving one side of a load and another amplifier (with an inverted signal from the first amplifier) driving the other side of the load. This results in 2x more voltage swing across the load than you would have in a single-ended configuration where one side of the load is tied to an amplifier and the other side to ground. Twice the voltage swing across the load equates to 4x the power to the load (P = V^2/R). So, a BTL load configuration offers 4x more power to the load than a single ended configuration from the same supply voltage. Be aware, that BTL amplifiers dissipate 4x the heat of a Single-Ended amplfier under the same supply voltage and load conditions. Refer to the TPA7x1 series parts in the applications section for more on BTL. Also note that the output DC blocking capacitors are NOT required in the BTL configuration. Since the load is tied across two amplifiers with the same DC bias and the signal across the load is the difference between the amplifier outputs, the DC bias is removed.
 

ramal121

Member
Joined
Dec 5, 2008
Messages
1,629
Location
Sonoma, CA
So the question is what is your speaker configuration? A single speaker connected to the correct output should cause zero problems for the life of the radio.

Are you running a tap to an unbalanced pa amp input? Do you have multiple speakers running off the radio? Something is not right here because speakers should not "become hot and fail".
 

jim202

Member
Joined
Mar 7, 2002
Messages
2,550
Location
New Orleans region
To put it in a little different light, there has been many threads about Motorola radios not grounding the speaker wires on either side of the speaker. Doing so would destroy the radio speaker output amplifier.

Not that much has been mentioned that the same thing can happen with the Kenwood mobiles. The best way to insure that you don't do damage, is to pull out your trusty volt meter and measure both sides of the speaker while the radio is on. This will show if there is a voltage to ground on the speaker wires. If so, you need to find another way to connect anything external that will ground one side of the speaker.

Most radios of the commercial class have other connections available to use as an external connection for RX audio output. But there is a good chance that even these connection points have a DC bias voltage on them. The use of a simple series coupling capacitor of around 1 uf. or so will block the DC bias voltage. You can then connect this connection into an external audio amp to drive a speaker system for building use as needed.
 
Status
Not open for further replies.
Top