RF SAMPLER

[Nikos Ntzanis (SV1RXI)]

i having the hermes lite 2 about a month and i am verry happy ,but for ps to operate i don’t have the knownledge to fix one by myself ,so i found a -40db sampler https://www.sv1afn.com/en/other/-32.html and want to ask how can i measure how much power this can handle ,how much can i push from my amp and the  hermes lite to be safe and handle the sample

[DL1YCF]

The „optimal“ PURESIGNAL feedback level is somewhere about -15 dBm.
This is *after* the signal went through the frontend preamp/attenuator
which has -12 … +48 dB.

So my advice is to have a sampler attenuation that produces (at most!) a -5 dBm signal
with the largest PA you want to use. This means

bare-foot HL2 +37 dBm output need 42 dBm attenuation
100 W PA +50 dBm Output need 55 dBm attenuation
1 KW PA +60 dBm output need 65 dBm attenuation

so you see 40 dB is too little. Note standard HPSDR radios have
a 0-30 dB step attenuator in the front end, but for the HL2 there
is less so you need a stronger attenuation in the sampler.

Got it?

> Am 13.01.2024 um 16:06 schrieb Nikos Ntzanis (SV1RXI) <sv1...@gmail.com>:
>
> i having the hermes lite 2 about a month and i am verry happy ,but for ps to operate i don’t have the knownledge to fix one by myself ,so i found a -40db sampler https://www.sv1afn.com/en/other/-32.html and want to ask how can i measure how much power this can handle ,how much can i push from my amp and the hermes lite to be safe and handle the sample
>

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[Mike Lewis]

The product page says 100W  CW for frequencies <54MHz.  If you have a 100W or less amp then it should work fine in any mode.

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From: herme...@googlegroups.com <herme...@googlegroups.com> on behalf of Nikos Ntzanis (SV1RXI) <sv1...@gmail.com>
Sent: Saturday, January 13, 2024 7:06:02 AM
To: Hermes-Lite <herme...@googlegroups.com>
Subject: RF SAMPLER

 

i having the hermes lite 2 about a month and i am verry happy ,but for ps to operate i don’t have the knownledge to fix one by myself ,so i found a -40db sampler https://www.sv1afn.com/en/other/-32.html and want to ask how can i measure how much power this can handle ,how much can i push from my amp and the  hermes lite to be safe and handle the sample

[Nikos Ntzanis (SV1RXI)]

I understand .Today i connected all and try to see how the ps works ,so i notice down right at my screen there is the feedback  and when  i right click there  is a number and i think this is mw ,this number is shown in a colour plate , blue ,green ,red .If the blue is low  the green is what we need and red is high , i suspect....but not sure. After i notice under the tune slider is the att value .Begin with 31db attenuation (if in hermes works ??) the 4-5w is blue ,the 50w is green and the 125w is red (danger/high?).Now if all this like i understand then the 40db from my sampler is low .After this i remeber that somewhere was having an 10db attenuator from the operation of the qo-100.I take this and put it direct behind the hermes 9ps line) and make again the operation.Well now with the 10db attenuator the 125w is blue , i low the att value from hermes from 31 to 26db and now the 125w output is green all the time .

So the 40db is low ....i need at least 50db ?

If the att from hermes is working ?

The green value is about 150 mw (feedback value number) ,this is what we need to operate safe?

Thanks 

["Christoph v. Wüllen"]

The feedback value should be around 155 then you are in the "green zone".
This is not a "mw" value but a relative amplitude.

Depending on the software you are using, there should be an automatic
calibration loop in the background, which (as long as you do a
two-tone experiment) should adjust the RF attenuator.

Note that formally the attenuation value goes (for the HL2) from
31 to -29, but the real value is an *amplification* that goes from
-12 to 48. This is why you need to a stronger attenuation in the
sampler for a HL2 compared to a HERMES board.

However something I do not understand:

"blue" normally indicates a too strong feedback signal, that is
you have to *increase* attenuation to go to the green zone.

But never mind, if you are "green" then the attenuation is fine.

DL1YCF Christoph

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