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TPL PA6-1AE UHF amp

 

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Hi all,

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I have the TPL PA6-1AE UHF repeater amp in stock here. Curious if anyone knows if the imput drive can be adjusted to support 10W drive instead of 5W?

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A radio tech looked at it and said that Kenwood TKR 850 repeaters don’t drive that amp well at 5 watts because the output at the low power setting bounces around and it can vary above 5W and fry the amp.

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If I can’t find any documentation on how to increase the drive input I will be looking for an amp that will accept 10W input, and have my current one up for sale.

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Thanks,

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Chad

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Might be safer to throw an attenuator in line.?
 

Bypass the pre driver board...the driver board is 8 to 15watts input....that's the PA6-1BE model

Chris WB5ITT


On Mon, Mar 31, 2025, 5:04 PM KK4IOH via <kk4ioh=[email protected]> wrote:
Might be safer to throw an attenuator in line.?
 

Chad,
If your TKR-850 is a Version 2 radio, the output should be stable at 5 watts in the low power setting. I have ran them as low as 1 watt and never had a problem.
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The early radios prior to the Version 2 series did have PA issues, but many of those were updated with a new PA deck under a Service Bulletin procedure by Kenwood.
?
Joe - WA7JAW
 

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Should've mentioned this in the message, but I have the 850 version two, and a TKR 851.
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Mar 31, 2025, at 5:30?PM, Joe Burkleo via groups.io <jburkleo@...> wrote:

?
Chad,
If your TKR-850 is a Version 2 radio, the output should be stable at 5 watts in the low power setting. I have ran them as low as 1 watt and never had a problem.
?
The early radios prior to the Version 2 series did have PA issues, but many of those were updated with a new PA deck under a Service Bulletin procedure by Kenwood.
?
Joe - WA7JAW
 

With the TKR-851 being designed for 1-25w operation, that's probably your best candidate for this application. I have two of them set aside here for future projects that require an external PA.?

Jeremy K1LFK?


On Mon, Mar 31, 2025, 5:31?PM Chad Nelson via <chad.nelson71=[email protected]> wrote:
Should've mentioned this in the message, but I have the 850 version two, and a TKR 851.
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Mar 31, 2025, at 5:30?PM, Joe Burkleo via <jburkleo=[email protected]> wrote:

?
Chad,
If your TKR-850 is a Version 2 radio, the output should be stable at 5 watts in the low power setting. I have ran them as low as 1 watt and never had a problem.
?
The early radios prior to the Version 2 series did have PA issues, but many of those were updated with a new PA deck under a Service Bulletin procedure by Kenwood.
?
Joe - WA7JAW
 

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Thanks, Jeremy that's good to know. I mentioned it to my radio guy. He didn't know much about the 851, so maybe that shop to deal with many of those. Do you know how oldthose radios are approximately? I'm talking about the manufacture dates of the TKR 851?
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Mar 31, 2025, at 5:48?PM, Jeremy Hansen via groups.io <jeremyhansen27@...> wrote:

?
With the TKR-851 being designed for 1-25w operation, that's probably your best candidate for this application. I have two of them set aside here for future projects that require an external PA.?

Jeremy K1LFK?

On Mon, Mar 31, 2025, 5:31?PM Chad Nelson via <chad.nelson71=[email protected]> wrote:
Should've mentioned this in the message, but I have the 850 version two, and a TKR 851.
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Mar 31, 2025, at 5:30?PM, Joe Burkleo via <jburkleo=[email protected]> wrote:

?
Chad,
If your TKR-850 is a Version 2 radio, the output should be stable at 5 watts in the low power setting. I have ran them as low as 1 watt and never had a problem.
?
The early radios prior to the Version 2 series did have PA issues, but many of those were updated with a new PA deck under a Service Bulletin procedure by Kenwood.
?
Joe - WA7JAW
 

To the best of my knowledge, the 751/851 production was close in alignment to the 750/850 version 2.

I'll defer to others here who own/operate/run Kenwood shops.

Jeremy K1LFK


On Mon, Mar 31, 2025, 5:52?PM Chad Nelson via <chad.nelson71=[email protected]> wrote:
Thanks, Jeremy that's good to know. I mentioned it to my radio guy. He didn't know much about the 851, so maybe that shop to deal with many of those. Do you know how oldthose radios are approximately? I'm talking about the manufacture dates of the TKR 851?
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Mar 31, 2025, at 5:48?PM, Jeremy Hansen via <jeremyhansen27=[email protected]> wrote:

?
With the TKR-851 being designed for 1-25w operation, that's probably your best candidate for this application. I have two of them set aside here for future projects that require an external PA.?

Jeremy K1LFK?

On Mon, Mar 31, 2025, 5:31?PM Chad Nelson via <chad.nelson71=[email protected]> wrote:
Should've mentioned this in the message, but I have the 850 version two, and a TKR 851.
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Mar 31, 2025, at 5:30?PM, Joe Burkleo via <jburkleo=[email protected]> wrote:

?
Chad,
If your TKR-850 is a Version 2 radio, the output should be stable at 5 watts in the low power setting. I have ran them as low as 1 watt and never had a problem.
?
The early radios prior to the Version 2 series did have PA issues, but many of those were updated with a new PA deck under a Service Bulletin procedure by Kenwood.
?
Joe - WA7JAW
 

I bought a couple of new TKR-851's from Kenwood when they were closing them out. That was 12 years ago. Hope that helps with the time line.

 

Chad,
The 851's were originally designed for the overseas market where 25 watts was the max allowed in some countries. Kenwood later on started selling them here in the US. They are roughly? based on the 850 Version 2 firmware and use the same software.
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They are rated for 1-25 watts continuous duty, where as the TKR-850 are 45 watt radios that are rated for continuous duty at 25 watts.
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If you have a TKR-851, that is the ideal radio to use with your amp.
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Joe - WA7JAW
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Hey joe, curious if I can drive that amp using a 5 W minimum from the repeater? Don't know how that tolerance is if it's one watt above the minimum of your level of the drive for the amp. My amp is rated for one to 4 W input, so don't want to burn it out
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Apr 1, 2025, at 6:10?PM, Joe Burkleo via groups.io <jburkleo@...> wrote:

?
Chad,
The 851's were originally designed for the overseas market where 25 watts was the max allowed in some countries. Kenwood later on started selling them here in the US. They are roughly? based on the 850 Version 2 firmware and use the same software.
?
They are rated for 1-25 watts continuous duty, where as the TKR-850 are 45 watt radios that are rated for continuous duty at 25 watts.
?
If you have a TKR-851, that is the ideal radio to use with your amp.
?
Joe - WA7JAW
?
 

Chad,
From what I see in the manual, it says 1-6 watts input for 70-100 watts output.
?
?
My experience with various TPL amps is that a little less drive is better than over driving them.
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It looks like the label on yours doesn't quite match this copy of the manual. That is not all that uncommon.
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I would start at 3 watts and work your way up. If you get to full output, that's where I would stop at with drive level.
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As was mentioned in a earlier post if you delete the pre-driver board your amplifier becomes a PA6-1BE and requires 10-15 watts drive for the 70-100 watts output.
?
Joe - WA7JAW
 

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Hey joe thanks for that, I'll have my radio shop guy maybe take a look at it and see what wecan do. I don't dare go in there because I'm blind and I don't know what I'm looking for.
Chad Nelson WI9HF/WRPL979
Janesville Wisconsin
608-754-8671
Send from my spectrum iPhone 16.

On Apr 1, 2025, at 9:12?PM, Joe Burkleo via groups.io <jburkleo@...> wrote:

?
Chad,
From what I see in the manual, it says 1-6 watts input for 70-100 watts output.
?
?
My experience with various TPL amps is that a little less drive is better than over driving them.
?
It looks like the label on yours doesn't quite match this copy of the manual. That is not all that uncommon.
?
I would start at 3 watts and work your way up. If you get to full output, that's where I would stop at with drive level.
?
As was mentioned in a earlier post if you delete the pre-driver board your amplifier becomes a PA6-1BE and requires 10-15 watts drive for the 70-100 watts output.
?
Joe - WA7JAW
 

Chad,
?
?
The easiest solution by far is an external power attenuator between the TPL amplifier and your transmitter to reduce power. This is a bolt on, or rather thread-on option that works easiest.
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Power attenuators are easy to order from Pasternack, ebay or Amazon and can be ordered with appropriate "N" connectors attached. Calculate the power you need to dissipate and the dB level of attenuation for the correct "drive", order appropriate model, then attach..... That simple!
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The above is the "solderless" solution to your problem........
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? ?You can't 100% rely on what the manuals say for TPL over at RB because if you own a later FET designed amplifier, they have no manuals for them, (RD60/RD70 FET) designs from the early 2000's onward till their demise.
?
Rick w6re
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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?
?
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.
?
Mike WA6ILQ
 

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Thanks I will take a look.

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From: [email protected] <[email protected]> On Behalf Of M M via groups.io
Sent: Wednesday, April 2, 2025 10:38 PM
To: [email protected]
Subject: Re: [repeater-builder] TPL PA6-1AE UHF amp

?

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?

?

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.

?

Mike WA6ILQ
 

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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



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?
?
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.
?
Mike WA6ILQ

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