One ANAN Using Two OM Amps with Pure Signal

WR4N
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One ANAN Using Two OM Amps with Pure Signal

Postby WR4N » Sun Jul 17, 2022 9:23 pm

I have an ANAN 7000 DLE MKII that I use with 2 OM amplifiers (OM-2501 Manual Tune & OM-2501 Auto Tune). The Manual Tune is dedicated to my dipoles (mainly 80 meters) and the Auto Tune is dedicated to my SteppIR Urban Beam. Pure Signal is such a huge game changer, that I hate to only be able to use it with just one amp (currently on the Auto Tune, with SteppIR, 10m-40m). Does anyone know of a unit that can be purchased that would allow PS sampling from 2 amps?
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w-u-2-o
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Re: One ANAN Using Two OM Amps with Pure Signal

Postby w-u-2-o » Sun Jul 17, 2022 9:41 pm

Surely you realize you can simply put an RF switch between the two amp coupler outputs and the bypass input on the back of the 7000, then select the proper coupler output as desired?
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w9ac
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Re: One ANAN Using Two OM Amps with Pure Signal

Postby w9ac » Sun Jul 17, 2022 11:51 pm

Taking Scott's suggestion a step further, you could automatically control the relay operation with Thetis' OC Control menu. Because you are dedicating each amp to specific bands, this should work well. Just pay attention to the open-collector rating. I like using Dow-Key flat SMA RF relays. They're RF-tight, reasonably compact, and well within the open-collector spec. Use a flyback diode across the relay coil if it's not integral to the relay.

Yet another possible option is a 2x1 combiner like this:

https://www.minicircuits.com/pdfs/ZFSC-2-1-75+.pdf
https://www.minicircuits.com/pdfs/ZFSC-2-6+.pdf [link updated to Z=50 version]

However, take note of the phase spec between input and output. Typical phase shift is 0.2 degs, but maximum is about 2 degrees. I've not yet seen nor conducted my own PureSignal sensitivity analysis as a function of sampling phase shift. But, it's enough to be mindful of phase-shift on PureSignal's ability to linearize.

In this application, I would lean toward Scott's suggestion of using a relay.

Paul, W9AC
Last edited by w9ac on Mon Jul 18, 2022 5:56 pm, edited 1 time in total.
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w-u-2-o
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Re: One ANAN Using Two OM Amps with Pure Signal

Postby w-u-2-o » Mon Jul 18, 2022 1:11 pm

The Dow-Key 402 series coaxial relays are great. I use one myself in my 100D external PureSignal switching modification. But you have to catch the right one on eBay and even then it will be $50 or $100. Right now 402's with 12V coils seem to be thin in the marketplace. You can get them at rfparts.com but then you'll pay $200.

The combiner idea is a good one. No switching or controlling required. And phase shift shouldn't be an issue. Phase shift is equivalent to delay. Consider how much phase shift (delay) there is in an average coax jumper cable at, say, 14MHz. And you can play with the Amp Delay setting in the Linearity menu to adjust for that if you wish.
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w9ac
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Re: One ANAN Using Two OM Amps with Pure Signal

Postby w9ac » Tue Jul 19, 2022 3:29 pm

The Dow-Key 401 is approximately 50% smaller than the 402 series but is only offered with SMA coaxial-type connectors, which I personally prefer when power isn't an issue. I've been using the 401-2208 for low-power RF switching applications. Overall specs of the 401 series are better too.

https://www.dowkey.com/wp-content/uploads/2015/05/01_Dow-KeyCatalog_SPDT_Coaxial_Section.pdf

A U.S. eBay seller has one new in a sealed blister pack for USD $45 including shipping. See item 284716311219. Even if you go the combiner route, it's good to have on-hand for other projects.

Paul, W9AC

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