[time-nuts] To use or not to use transmission line splitters for GPS receivers

Timeok timeok at timeok.it
Tue Oct 9 09:57:49 EDT 2012


Paul,

I am convinced your realization work very well and it is a lower cost 
in the market.

But depend what kind of user have to use the device.
For a standard laboratory or a company I am sure is not sufficent your 
realization, for an hobbist yes, can be.

Business or research company  want to have a datsheet with temperature 
range, technical characteristic, a repair service. In one word a 
professional package.

Me for example, am an hobbist and I am started from the tv sat splitter 
but now,  I have bought on ebay a low cost professional splitter.It is 
better than mine at least as mechanical realization ad impedance 
matching.

That's all.

All the people in time-nuts community want to improve day by day the hw 
and sw they have at home.

yes, yesterday night I have bring a bier. Cirio!

Luciano
timeok



Il 2012-10-09 15:15 paul swed ha scritto:
> Lots of comments. Indeed it sounds like a great discussion for pizza 
> and
> beer. The more beer the more lively. Did they bring beer?
> Fact
> I have used a 8 way splitter Sat/TV for 5 years now. Port to port 
> loss is
> something like 16 db or 26 db as I recall. It has dc blocking on all 
> but 1
> port built in. The loss was as advertised. The cost was pretty high 
> at $7.
> To make up for the loss I used a amplifier. A Mar circuit and only 
> enough
> gain to cover the splitter loss since the single antenna has 30db of 
> gain
> and feed 1/2" hardline. So if all of things discussed are happening 
> its not
> at all apparent from the 6 rcvrs on the system. Some old like odetics
> austrons some newer like 3801s and Tbolt...Plus I never have to hunt 
> for a
> port for experimenting.
> There is one catch and this can apply to all splitters some rcvrs 
> need a dc
> load so that they think they have an antenna. I think about 430 ohms. 
> As I
> say its been 5 years and it just works.
> Total investment $10??
> Though it doesn't say HP on it.
> Regards
> Paul
> WB8TSL
>
> On Tue, Oct 9, 2012 at 7:14 AM, Robert Atkinson
> <robert8rpi at yahoo.co.uk>wrote:
>
>> When GPS first started to be fitted to light aircraft it was found 
>> that LO
>> leakage from some VHF navigation recivers blocked the GPS when the 
>> NAV was
>> on certain channels. You can buy a BNC "T" adaptor where the leg of 
>> the T
>> is a 1.5GHz coax stub notch filter. They go on the NAV RX antenna 
>> connector.
>>
>> Robert G8RPI.
>>
>>
>> ________________________________
>> From: gary <lists at lazygranch.com>
>> To: time-nuts at febo.com
>> Sent: Tuesday, 9 October 2012, 8:51
>> Subject: Re: [time-nuts] To use or not to use transmission line 
>> splitters
>> for GPS receivers
>>
>> I was wondering about that myself, but my guess is the crosstalk 
>> would be
>> from whatever grunge was coming from the other GPS. Every amplifier 
>> has
>> reverse parameters, so a small amount of the crud (circuitry noise) 
>> from
>> one GPS will reach the other GPS. Not much, but some people are nuts 
>> about
>> time.
>>
>> This is a bigger problem with radios, where the locals from one 
>> radio can
>> reach the input to the other radio.
>>
>> I was also confused on the notion of a transmission line splitter. 
>> Is this
>> a Wilkinson or something else?
>>
>> On 10/9/2012 12:40 AM, Azelio Boriani wrote:
>> > Crosstalk? With the same signal?
>>
>>
>>
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-- 
timeok




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