Xtronic XDC-4SO Additional Attenuation

Pete4638
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Xtronic XDC-4SO Additional Attenuation

Postby Pete4638 » Thu Feb 02, 2023 1:48 am

I ordered an Xtronic-4SO coupler. The plan is to implement PureSignal on my 7000DLE MKII using an ACOM 1000 amplifier. The published specs for the Xtronic coupler are as follows:

Frequency: 1 - 60 Mhz
Power: 3,000 Watts PEP
Coupling: 44db +/- 1db
Insertion Loss: 0.04db
Return Loss: 30db
Directivity: 35db

At the bottom of the page, there is a note: ** For higher power stations, Additional 10dB and 20dB inline SMA attenuators are available for $10.95 each. - See Accessory Listing Below

How do I calculate if the Xtronic coupler has enough attenuation for this Amplifier? I am guessing that there is a formula, but I have not been able to find it. Xtronic has not answered the phone or replied to my email inquiry and the fellow at Ham Radio Outlet that I talked to said that he didn't know the answer. Unfortunately, Ham Radio Outlet didn't have the optional Xtronic attenuators in stock.

Thanks - Peter Bucy - W4WHQ
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w-u-2-o
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Re: Xtronic XDC-4SO Additional Attenuation

Postby w-u-2-o » Thu Feb 02, 2023 2:14 am

The information you seek is in a topic tacked right at the top of this sub-forum that you posted in. It is entitled "External feedback level calculations".

You'll want a minimum of 3dB extra attenuation, 6dB for a little safety margin, 10dB will work fine.
Pete4638
Posts: 13
Joined: Mon Aug 10, 2020 10:46 pm

Re: Xtronic XDC-4SO Additional Attenuation

Postby Pete4638 » Thu Feb 02, 2023 2:24 am

Thanks for the information.
Pete4638
Posts: 13
Joined: Mon Aug 10, 2020 10:46 pm

Re: Xtronic XDC-4SO Additional Attenuation

Postby Pete4638 » Fri Feb 03, 2023 12:02 am

I used the formula listed in this sub-forum to calculate the additional attenuation that my ACOM 1000 watt amp would need when using an Apache Labs 7000 DLE MKII. The result was 2 dBM of additional attenuation needed.

Attenuation rating of coupler dB= 44

7000/8000 Apache Labs Radios 1000 60.00 44 16.00 14.00 2.00

I have a 10db attenuator on order from DX Engineering. I'm looking for a variable/step attenuator 0-10 db. I'd like to match the attenuation with the calculated dBM as closes as possible.
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w-u-2-o
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Re: Xtronic XDC-4SO Additional Attenuation

Postby w-u-2-o » Fri Feb 03, 2023 1:00 am

That's a good calculation, but it's important to be mindful of the max. +13dBm limit on the input in order to avoid possible damage from too much power. Also consider that your amp might actually exceed 1000W peak occasionally.

Having an adjustable attenuator does provide a lot of flexibility. There are usually good deals on eBay. Search for "rotary attenuator" and "step attenuator". I did a quick look just now and saw a couple of good choices for under $50.
Pete4638
Posts: 13
Joined: Mon Aug 10, 2020 10:46 pm

Re: Xtronic XDC-4SO Additional Attenuation

Postby Pete4638 » Fri Feb 03, 2023 4:59 pm

You are right. The ACOM 1000 is rated for 1000 watts, in it can easily produce 1200 watts without damaging its very robust tube. I just found a new JFW Industries 50R-019 Manual Attenuator DC 0-2.2GHz 0-10dB x 1dB SMA on Ebay for a reasonable price. It should add some flexibility to setting the correct attenuation for the Xtronic coupler.

Granted, I need to do a some reading before implementing Pure Signal. Is there someplace in the Pure Signal setup where I can see what the +dBm input is to the 7000dle MKII? What is the best source of information for setting up Pure Signal?

Thanks - Pete - W4WHQ
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w-u-2-o
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Re: Xtronic XDC-4SO Additional Attenuation

Postby w-u-2-o » Sat Feb 04, 2023 2:27 am

Have you read all the tacked threads in this sub-forum?

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