High Frequency parts?

[SouthernSky]

Dumb question probably but what is the difference between HF ground blocks, switches, etc., versus normal ground blocks, switches, etc.???

They are advertised in Perfect-10's catalog but when/what are they used for and how are they different? They cost as much as double but there was no description of when they are used.

Thanks.

[boba]

Perfect 10 has an 800# call them and ask.

[SouthernSky]

I did. Oddly enough, the regular salespeople aren't sure.

[Mike500]

There's not much difference in Perfect 10's high frequency parts. Other than silver color plated and with blue insulating plastic, there appears to be no difference inside. The contacts are still two flat spring like contacts. They just have been tested to 3 Ghz.

The Thomas and Betts and the Stirling components are much better. The sockets are machined and tubular and flared at the open ends to take .030 to .040 (18-17 gauge) wire center conductors on RG6 coax.

Check out:

http://catv-cat.tnb.com/tnbcat/tnbcat/webcat_search_results_dsp2.build_category_home_pag e?p_catalog_code=LRC&p_category_hier_id=LRC40&p_div=D

and

http://www.stirlingcanada.com/

[waydwolf]

High frequency ratings in DBS supplies aren't ratings as any engineer would really see it. What you have in this is marketers misusing technical terms to sell product.

Anyone with an oscilloscope can do one of these tests. I've seen splitters rated 45-500Mhz pass the return path of cable modems which lies between 5-42Mhz(often around 22Mhz) as well as the downstream at 556Mhz even above 700Mhz. The only reason it would if it was a splitter with an internal circuit which specifically filtered selected bands. Most aren't. But some are built so cheaply they quickly attenuate above a certain range.

It's like people who tell you that you need special fireclay for making a kiln when ancient people used to use just plain natural clay right out of the ground. I've built aluminum melting furnaces with cat litter clay and Portland cement. (you should use non-clumping as clumping is usually a high montmorillonite content type which expands as much as three times its size when wet, and thus shrinks as much when drying; a little improvised science each day is always a good idea).

If you know the physics, then that will tell you what will work. Generally, go with Perfect 10 for supplies, go by the ratings, and they should at least work for what they claim, when it comes to splitters and diplexors. But ground blocks and fittings will work just fine which work fine in cable. Remember that the bulk of a fitting is to act as a conduit continuing the shield layer of the coax uniformly as well as secure itself to the coax tightly. The stinger in the coax is what carries signal. In a Faraday cage, a simple bare copper wire will cary many Ghz easily. In the real world shielding against ingress and thermal noise as well as leakage is the real concern as well as any actual circuits through which the signal passes.

[AntAltMike]

Most splitters that are "rated" to 2Gz roll off terribly starting at about 1.7Gz- 1.8Gz. Especially the ones that say Tru-Spec 950Mz-2050Mz.

When I am installing a stacked LNB system that demands the flattest possible performance at the high end of the L-band, I pay the extra couple of dollars for splitters and taps from Sonora Design. I might lose 6dB through a two-way Sonora splitter at 2Gz whereas I might lose 8dB through a Tru-Spec. But for those of you using passive components in 950Mz-1,450Mz systems, you can feel safe using any cheap product of your choosing.

Holland Electronics makes passive components priced at the low end that they claim seize the whole center conductor. I have not broken one open to make sure that they do, but I have a fairly high degree of confidence in that claim because they furnish exploded view drawings of their "seizing mechanism" and they would look like jerks if the product construction didn't match the drawings.