Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KB2E, Jul 31, 2019.
Say hello to the monks.
Are they still living up there?
Apparently. They took down the motel at the top and replaced it with the Saint Bruno Scenic Viewing Center.
Enjoy videos that capture the Monastic life of the Carthusian Monks or visit the meditation/prayer chapel with a Statue of Saint Bruno, founder of the Carthusian order. There is a statue of the holy family, a mannequin of a Carthusian monk, and artifacts of a Carthusian's cell.
Yes, I knew about that.
I haven't been there in 20+ years but if I returned I'd miss the motel "The Skyline Inn." It was old, but it was actually great. Nice bar, good food, passable rooms.
When I used to do multi/multi contests from there in the early 70s, we'd book six rooms and use them all, which made the Mutzes very happy. We got to know them well after several visits.
So what would be an acceptable source clock ppm be for 50, 144, 220MHz transverter operation? Like, are we after ~ 1Hz drift?
I've found some that's ~ 0.5ppm but that's still 197Hz drift at 197MHz. Ok for FM, but not that great for ssb/data. So I'm looking at what it'd take to make higher ppm sources for 144, 220, 440 and 900MHz transverter designs.
This is a flexible L.O. signal source (programmable) that has a 0.28 ppm high stability option available...total cost with the high stability option is $144.
That's almost double the cost of the Ukranian transverters (!) but may be worth it.
The DigiLO (I have one) can also lock to an outboard high stability 10.000 MHz signal source, as many SHF ops do (those mostly on 2304 MHz and above, to 24 GHz and higher).
So is 0.25ppm considered "ok" here? like, at 220MHz that's ~ 55Hz drift; at 1.2GHz that's ~ 300Hz. Is that considered "OK" for VHF/UHF SSB/data comms?
Remember, it's not so much "drift" as it is "inaccuracy."
My experience with VHF L.O.s in transverters, and I've had a bunch of them beginning with Microwave Modules units in the mid-1970s, has been they're actually quite stable after a brief warmup period. What they can lack is accuracy to begin with, whether warmed up or not.
At 1.2 GHz, 300 Hz is considered very good and very "close." If you buy two TS-2000s with the 23cm modules and use them to work each other it's very likely they'll be 300 Hz apart. Ditto with IC-9100s. Not sure about the new IC-9700, but maybe that one, too. 300 Hz error or drift at 1.2 GHz is likely well "within specification" for all these rigs.
It becomes a bigger issue at, say 10,368.1 MHz, which is the SSB calling frequency on the 3cm band. There, for contest work, many of use just us NBFM, where 2-3 kHz error still allows you to copy people. On SSB everybody tunes around a lot.
Heh, ok. I'm going to order some digitally programmed TCXO modules to see if they're suitable to drive this ukrainian transverter.
Also, that's good to know. My "new" icom IC-1271A (23cm band) is a couple hundred hertz off and stays there, which is nice. I guess that's OK for now!
I am hoping to try and make some simplex contacts with that soon.
The new data modes can require a lot of stability. People were complaining about 35Hz drift on the IC-9700 so Icom and others came up with a fix for that. Icom wasn't expecting users to lock their radios to a reference oscillator.
Yes, narrowband data modes are picky.
Of course, VHF-UHF-SHF work in general can be tricky. Even weak-signal satellite users know about Doppler shift -- doesn't matter how stable your rig is, the signals will change frequency anyway.
A lot of higher frequency work is "one hand on the dial" type stuff.
Those who have built or used high powered amplifiers for 70cm and above (33cm, 23cm, etc) using tubes understand the "one hand on the tuning" quite well, also. Sometimes two hands. My own homebrew 70cm tube amp (4CX250Bs) with a solid brass tuned line supported by multiple Teflon standoffs and a tuning flapper that is so stiff you almost need a wrench to turn it drifts enough from cold to hot that if you don't keep one hand on the tuning, you're in trouble.