On 2015-07-17 00:51, David J Taylor wrote:
> From: jdow
>
> Since he's already using two connectors that are really dreadful above about 100
> MHz he might as well simply use mending tape and twisted wires to make an
> adapter. It'd not be much worse. He has the antenna that came with the dongle
> for the correct sex for the PAL connector. And he has the PL259 to mcx adapter.
> If he doesn't want to "bank" that adapter pending purchase of another dongle he
> can mash the two together without losing too awfully much.
>
> {^_-}
> ================================
>
> Might work OK for HF work - the DC bands!
>
> Actually, the Belling-Lee TV connector works well enough for TV (analogue and
> digital) up to some 800 MHz, as tens of millions of homes in the UK can testify,
> and likely that's why the particular device has been fitted with such a connector.
>
> Larger diameter cables are an issue. For use on 144 MHz and lower the UHF
> connector is "not bad", and perhaps less critical in matching connector to cable
> size than the N-type.
>
> 73,
> David GM8ARV
Some information I found on the connector suggested it's not as good as the F
series. It's fair at best above about 100 MHz. It's cheap. The same can be said
for the so-called "UHF" connector, PL-259 and SO-259. They are usable but
present high VSWR bumps in the feed line path when you view it with Time Domain
Reflectometry. Again, the F series outperform the connector. From this comes the
shrug, strip and twist 'em together comment. If I was replacing connectors and
wanted to use the dongles say for GPS reception I'd use SMA connectors. Then for
a long run I'd use a short N to SMA pigtail adapter. (And I'd pray the pigtail
was carefully and professionally assembled. But, Pasternak is expensive.)
Come to think on it with typical 1/4" RF cables the connector at the end of a 10
meter run would not make much difference to the already rather high loss at tens
of centimeters wavelengths. Antenna mounted preamps are nice creatures in that
frequency range.
Type N is nice for large cables, which you should use for cables of any length
over 6' or so at near GHz frequencies. Better connectors exist. (For awhile
there were defects in the N connector leading to high VSWR in the GPS band
frequencies. That's been fixed. SMA is a better connector for 1/4" cables. For
Thumb size cables you're in a bind that sticks you with N. The fat cables stop
working at frequencies somewhat above the dongle frequencies as the cable
dimensions become a bit part of the wavelength. You get multiple propagation
modes within the cable leading to losses and other problems. BNC is handy, but
it wobbles making its VSWR performance unreliable.
{^_-}