Re: [time-nuts] Active LORAN antenna

[George Dubovsky]

Ulrich,

I have the SRS active antenna schematic FS700-14, Revision B, and it is
identical to Stan's schematic except that my R3 is 1k and his is 100k. Don't
know which is the newer schematic.

73,

geo - n4ua

On Fri, Aug 26, 2011 at 9:02 AM, Stan, W1LE  wrote:

> Hello UL,
>
> My SRS active antenna is internally potted in resin, so tracing the circuit
> is difficult.
>
> I was able to chip away the PVC white housing and some of the black potting
> material to get at the antenna input terminal. Then I repackaged it with a
> new CB antenna.
> Living on Cape Cod, quite near to the former Nantucket Loran station, I can
> only rarely receive
> some of the European stations.
>
> The schematic in the manual shows a switch or a jumper for the gain
> reduction.
> So, the schematic is probably an old version, and "all bets are off" as to
> what
> the production models, we have, consist of.
>
> I did buy the manual form SRS and the active antenna schematic shows a
> 2N5951,
> not the 2N5991 you mention. My schematic is a rev B, Document Number
> FS700-14
> This document in not dated.
>
> The frequency selective L-C filter network is different, see attachment.
>
> If the attachment does not get thru, please send your direct e-mail
> address.
>
>
> Stan, W1LE Cape CodFN41sr
>
>
>
>
>
> On 8/26/2011 6:00 AM, Ulrich Bangert wrote:
>
>> Gentlemen,
>>
>> my friend Frank and I both miss the matching actice antenna for our
>> Standford Research FS700 Loran frequency standards. We also do not have a
>> schematic of it. Nevertheless we have tried to re-engineer the circut from
>> the part's list and the circuit description in the FS700 manual. Our
>> result
>> is shown in the accompanying schematic.pdf.
>>
>> The generator in the left in conjunction with the 10 k resistor represents
>> the expected high footpoint impedance of the very short (3 m) antenna. The
>> VDD in the right in conjunction with the 100 ohms resistor represents what
>> it believed to be inside the FS700.
>>
>> Not shown here is a 100 k resistor that may be included between the filter
>> output and the 7 k resistor to form a 30 dB divider together with it. Also
>> not shown is a 390 micro henry inductance which's impact is not to be
>> found
>> in the circuit descripion. Also not shown is a small neon bulb for
>> overvoltage protection.
>>
>> The ac analysis shows that the overall filter function is well around 100
>> kHz. But it seems as if the fet (a 2N5991 in the original) would not have
>> enough gain to counteract the overall damping included in the front end
>> let
>> alone to deliver some additional gain for the receiver's front end.
>>
>> We both feed the receiver currently with dipoles for 80 m ham radio and a
>> resistor that makes the receiver think the active antenna is connected.
>> The
>> receiver has a possible total of 130 dB gain and my receiver says it uses
>> 94
>> dB gain while Franks receiver says it uses 102 dB gain. The noise margin
>> is
>> also a bit better on my location. However, if one looks at the manual f.e.
>> at page 17 one could get the impression as if a receiver gain of 75 dB may
>> be considered much more normal as our values. Instead of improving the
>> reception everything gets even worse if the active antenna is connected. I
>> should also note that my qth is only 200 km away from SYLT (our German
>> Loran
>> station) while Frank is even 70 km nearer to it.
>>
>> Questions:
>>
>> 1) Anyone an idea what we are possibly doing wrong?
>>
>> 2) Anyone an idea for the 390 micro henry inductor?
>>
>> 3) Anyone own the original schematic?
>>
>> TIA for your help
>>
>> Ulrich Bangert
>> www.ulrich-bangert.de
>> Ortholzer Weg 1
>> 27243 Gross Ippener
>>
>>
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>
>
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[time-nuts] Using a lock-in amplifier

[Don Lewis]

This might be off topic, and if so, pls disregard. (I am new to your
group..just listening lately, a little rusty on some of your talents.)

 

I have an older EG&G Model 5202 Quadrature lock-in amplifier around for
years waiting for a project. (.2 - 50Mhz)

 

It seems its' phase sensitivity could be used to discipline an oscillator to
a high degree of accuracy using its' DC-output.

 

Maybe it's not what it was designed for .I'm trying to find a use for it.

 

Thanks,-Don

 

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Re: [time-nuts] Using a lock-in amplifier

[J. Forster]

They are good instruments.

You can certainly use them to compare the phase of two sources.

Because it's a quadrature lock-in, you can also use it to sit on a peak
with a small dither (Pound Locking).

Best,

-John








> This might be off topic, and if so, pls disregard. (I am new to your
> group..just listening lately, a little rusty on some of your talents.)
>
>
>
> I have an older EG&G Model 5202 Quadrature lock-in amplifier around for
> years waiting for a project. (.2 - 50Mhz)
>
>
>
> It seems its' phase sensitivity could be used to discipline an oscillator
> to
> a high degree of accuracy using its' DC-output.
>
>
>
> Maybe it's not what it was designed for .I'm trying to find a use for it.
>
>
>
> Thanks,-Don
>
>
>
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>



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Re: [time-nuts] Question for any HP105 owners

[Tom Van Baak]

Hi Mark,

What reference oscillator and measurement system did you use?
Is that with or without a sqrt(2) removed? Is your HP105 the older
style with the 00105 brick oscillator or a newer one?

The modern HP105 is essentially a well engineered wrapper around
a 10811 oscillator so the performance you see will be that of the
10811. Your 3e-12 measurement beats the spec for a 10811 (1e-11
at tau 100 s) by a wide margin.

It is possible that the 10811 used in HP105 met some higher spec
or were hand selected. I don't know. Perhaps someone from HP
(Rick?) could clarify this for us. We do know there are a number
of different grades of 10811.

One lesson you learn if you test many 10811 is that they can vary
by quite a lot (an order of magnitude or more), even those with the
same part number in the same instrument model.

For example, see the tau 100 second point of a dozen 10811's:
http://leapsecond.com/pages/z3801a-osc/z3801a-13-adev-m.gif
Notice they all are under the 1e-11@100s spec, but some are
much better than others. It's the luck of the draw. And one reason
why some of us troll eBay for old or cheap 10811 hoping to find
one that's better than the previous best.

/tvb

- Original Message - 
From: "Mark Spencer" 

To: 
Sent: Saturday, August 27, 2011 4:53 PM
Subject: [time-nuts] Question for any HP105 owners


Just curious what a typical ADEV figure is for the HP105 ?  Mine seems to be approx 3X10-12 at 100 seconds.  Just 
curious what results any other HP105 owners have seen in practice.


Thanks in advance
Mark VE7AFZ



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