Empathy List Archives

MS

Martyn Smith

Fri, Aug 15, 2008 8:31 AM

I read with interest about the new 10 MHz distribution amplifier.

But I agree with everyone, it's the specs that are missing that are
important.

But I wanted to take one comment up about AGC.

My company makes a nice distribution amplifier and we do have AGC. The nice
thing here is that a +7 dBm input (e.g PRS10 output) will give you up to +13
dBm output.

Despite the AGC we still achieve good phase noise (-135 dBc/Hz @ 1 Hz with
a -168 dBc noise floor) together with 130 dB isolation and 10 ps/C phase
stability.

I suspect this low cost unit has a -140 or -150 dBc noise floor.

But our unit costs a lot more than this low cost design, so maybe I'm not
being fair in comparing.

www.ptsyst.com/DA1-100-10-B.pdf has all our specifications.

I could probably talk our sales manager in a once off big discount for time
nuts readers, but I suspect it would still be out of the range of amateurs.

Send me an email if you are interested (martyn@ptsyst.com)

Martyn

I read with interest about the new 10 MHz distribution amplifier. But I agree with everyone, it's the specs that are missing that are important. But I wanted to take one comment up about AGC. My company makes a nice distribution amplifier and we do have AGC. The nice thing here is that a +7 dBm input (e.g PRS10 output) will give you up to +13 dBm output. Despite the AGC we still achieve good phase noise (-135 dBc/Hz @ 1 Hz with a -168 dBc noise floor) together with 130 dB isolation and 10 ps/C phase stability. I suspect this low cost unit has a -140 or -150 dBc noise floor. But our unit costs a lot more than this low cost design, so maybe I'm not being fair in comparing. www.ptsyst.com/DA1-100-10-B.pdf has all our specifications. I could probably talk our sales manager in a once off big discount for time nuts readers, but I suspect it would still be out of the range of amateurs. Send me an email if you are interested (martyn@ptsyst.com) Martyn

B

BNeubig@t-online.de

Fri, Aug 15, 2008 10:56 AM

Hello Martyn,

Martyn Smith martyn@ptsyst.com wrote:
Despite the AGC we still achieve good phase noise (-135 dBc/Hz @ 1 Hz
with
a -168 dBc noise floor) together with 130 dB isolation and 10 ps/C phase
stability.

I have problems to understand, how your amplifier can achieve phase
noise of -135 dBc/Hz @ 1 Hz. Such a dBc/Hz measure is related to a
carrier, but where does the carrier in your amp come from?
The same applies to the graph in your data sheet. This obviously shows
the phase noise of an oscillator, which feeds your distribution
amplifier, not the inherent noise of the amplifier. It needs a different
measurement technique to characterize the inherent noise of an
amplifier, and there are different numbers to come out of that.
At this point I am not able to argue about the -135 dBc/Hz @ 1 Hz for
your OCXO, as you do not specify, what model and brand that is.

Regards

Bernd Neubig
DK1AG

AXTAL GmbH & Co.KG
www.axtal.com

Hello Martyn, Martyn Smith <martyn@ptsyst.com> wrote: Despite the AGC we still achieve good phase noise (-135 dBc/Hz @ 1 Hz with a -168 dBc noise floor) together with 130 dB isolation and 10 ps/C phase stability. I have problems to understand, how your amplifier can achieve phase noise of -135 dBc/Hz @ 1 Hz. Such a dBc/Hz measure is related to a carrier, but where does the carrier in your amp come from? The same applies to the graph in your data sheet. This obviously shows the phase noise of an oscillator, which feeds your distribution amplifier, not the inherent noise of the amplifier. It needs a different measurement technique to characterize the inherent noise of an amplifier, and there are different numbers to come out of that. At this point I am not able to argue about the -135 dBc/Hz @ 1 Hz for your OCXO, as you do not specify, what model and brand that is. Regards Bernd Neubig DK1AG __________________ AXTAL GmbH & Co.KG www.axtal.com

BG

Bruce Griffiths

Fri, Aug 15, 2008 1:35 PM

Martyn Smith wrote:

I read with interest about the new 10 MHz distribution amplifier.

But I agree with everyone, it's the specs that are missing that are
important.

But I wanted to take one comment up about AGC.

It depends how the AGC is done, there are some really poor examples for
sale.

My company makes a nice distribution amplifier and we do have AGC. The nice
thing here is that a +7 dBm input (e.g PRS10 output) will give you up to +13
dBm output.

Despite the AGC we still achieve good phase noise (-135 dBc/Hz @ 1 Hz with
a -168 dBc noise floor) together with 130 dB isolation and 10 ps/C phase
stability.

The phase noise at 1Hz offset is about 15dB or so higher than the state
of the art.
The effect of AGC should be most noticeable at low offsets.
A phase tempco of 10ps/C is a bit for high precision work.

I suspect this low cost unit has a -140 or -150 dBc noise floor.

But our unit costs a lot more than this low cost design, so maybe I'm not
being fair in comparing.

www.ptsyst.com/DA1-100-10-B.pdf has all our specifications.

I could probably talk our sales manager in a once off big discount for time
nuts readers, but I suspect it would still be out of the range of amateurs.

Send me an email if you are interested (martyn@ptsyst.com)

Martyn

Bruce

Martyn Smith wrote: > I read with interest about the new 10 MHz distribution amplifier. > > But I agree with everyone, it's the specs that are missing that are > important. > > But I wanted to take one comment up about AGC. > > It depends how the AGC is done, there are some really poor examples for sale. > My company makes a nice distribution amplifier and we do have AGC. The nice > thing here is that a +7 dBm input (e.g PRS10 output) will give you up to +13 > dBm output. > > Despite the AGC we still achieve good phase noise (-135 dBc/Hz @ 1 Hz with > a -168 dBc noise floor) together with 130 dB isolation and 10 ps/C phase > stability. > > The phase noise at 1Hz offset is about 15dB or so higher than the state of the art. The effect of AGC should be most noticeable at low offsets. A phase tempco of 10ps/C is a bit for high precision work. > I suspect this low cost unit has a -140 or -150 dBc noise floor. > > But our unit costs a lot more than this low cost design, so maybe I'm not > being fair in comparing. > > www.ptsyst.com/DA1-100-10-B.pdf has all our specifications. > > I could probably talk our sales manager in a once off big discount for time > nuts readers, but I suspect it would still be out of the range of amateurs. > > Send me an email if you are interested (martyn@ptsyst.com) > > Martyn > Bruce

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New 10 MHz Distribution Amplifier