Jim--
The accuracy numbers always quoted for Birds has always bothered me. The
accuracy numbers are a combination of "Cover your A**" and laziness. The
real problem usually is repeatability, not accuracy. Most comparisons
are just that, comparisons with one set of instruments. The use of a
single instrument for multiple measurements with careful constancy of
non-critical items can give far more realistic answers.
I, personally, did a multi-connecter comparison using UHF parts. I
hooked up a long string of UHF jumpers and barrel connecters with
"Push-on" fittings at each end. My "Instruments were only the Watt
meters most hams have. I don't remember how many joints were involved,
but was every spare jumper I had and all the Barrels in the junk box.
There was no attempt to get great accuracy, but I did try for
repeatability and replication.
With this setup, I could measure no significant losses. I am convinced
(I convinced myself) that the "UHF connector loss" is a myth, right up
there with that myth about the superiority of N-type at HF.
Bill--W4BSG
On 1/14/2012 11:32 AM, Jim W7RY wrote:
> That's hardly believable. How was it measured? a Bird wattmeter accuracy is
> only +- 5%. A network analyzer or a TDR in return loss mode (Bird SA-6000 or
> Anritsu equivalent) would be required to measure this accurately.
>
> Not to mention, the number of 75 Ohm adapters in the string shown.
>
>
>
> 73
> Jim W7RY
>
>
> --------------------------------------------------
> From: "Steve Hunt"<steve@karinya.net>
> Sent: Saturday, January 14, 2012 9:15 AM
> To:<towertalk@contesting.com>
> Subject: Re: [TowerTalk] PL259 Insertion Loss?
>
>> Not a direct answer to your question, but from Dan's (N3OX) web site:
>>
>> http://n3ox.net/files/23_adapters_28400kHz.jpg
>>
>> 23 connectors/adaptors including UHF types, 0.08dB loss on 10m
>>
>> 73,
>> Steve G3TXQ
>>
>>
>>
>>
>> On 14/01/2012 16:59, Tony wrote:
>>> All,
>>>
>>> I've always assumed that UHF connectors had negligible insertion loss
>>> below 30MHz, but I recently spotted a couple of quotes on the web that
>>> put losses between 0.3 and 0.5db @ 30Mhz. If that were the case, the
>>> cumulative effect of a typical installation with 6 to 8 connectors would
>>> not be so negligible, especially on 10 and 12 meters.
>>>
>>> I was wondering if anyone has done any tests of their own or if they
>>> know of a reliable source on the web for this kind of data? Another
>>> thing that comes to mind is whether there is any additional losses
>>> associated with UHF crimp-on connectors?
>>>
>>> Thanks,
>>>
>>> Tony, K2MO
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|
