> Being new to repeaters, I've been doing a lot of research and > reading though the LBI's available in repeater-builder.com (thank you > to all who contributed, btw). I have learned LOTS. For my first > VHF "learning" repeater I plan to use a couple GE Deltas (an SX for > transmit and an S for receive due to the helical filters). First > question: has anyone experienced issues with turning the PA on the > 110-Watt delta transmitter down to 50 to 60 Watts with a fan for full > duty cycle? I'm concerned with spurs of course.
The Delta-S's, both on highband and UHF, seem to be very stable at any power level. I've had issues with lowband Delta-S's programmed at the high end of 6m (52/53 MHz pairs) sometimes getting unstable at certain power levels. However, even with the TPO turned down, there are still thermal issues. You're better off with a low-power radio (or even better, putting a low-power PA in a high-power chassis to take advantage of the bigger heatsink). > or advice to give? I don't mind learning from my mistakes, but I'd > rather learn from others'. :) If you haven't already found it, go to http://www.ka9fur.net/delta/delta.html for additional info beyond what is on repeater-builder.com. Some of it is specific to UHF, but there is a lot of good general info there, including dissection of the EEPROM storage format. > Secondly, more often than not I have read that people toss the > Channel Guard boards in these radios for HAM use. Why is that? I don't know, I've never heard of anyone doing that. The software decoder in the Delta-S is very good. > Anyone actually use the board for tone > squelch? Most definately. > You can I'm curious why someone would go with something like a TS- > 64 when the CG board accomplishes the same task. I don't know, the ComSpec PL boards aren't the greatest as far as decode performance, and the encoders have higher THD than most other designs. > Incidentally, I am considering replacing the micro/prom in the > Delta with a micro of my own (I fancy the Atmel line, though any > would do.) While we haven't totally replaced the uP, Dave (KA9FUR) and I have come up with some software mods to facilitate customization of radios for non-standard uses such as locking to external frequency references (for simulcasting) among other things. Finding windowed (EPROM) parts (8749H) is getting difficult though. > As you can tell I'm loving these radios (and similarly, > the Phoenixes) so far... They're great radios. The Delta-S front end is very good, and is virtually identical to the front end in GE Mastr III's. Transmitters are extremely clean with low phase/sideband noise. I was told that the design criteria of the Delta-S/SX series included the requirement that sideband noise was to be less than current protection crystal-based transmitters (at the time, Mastr II series), and from all indications, they have exceeded that specification. Duplex operation on 2m seems to be comparable to the Mastr II PLL exciter, which represents about a 22 dB reduction in noise over the standard multiplier Mastr II exciter at 600 kHz T/R spacing. --- Jeff -------------------------------------------- Jeff DePolo WN3A - [EMAIL PROTECTED] Broadcast and Communications Consultant -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/282 - Release Date: 3/15/2006 Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
