NV4B/R 224.340 Repeater
Coordinated by the Alabama Repeater Council
Status:
UNDER CONSTRUCTION
This repeater is mainly for experimental purposes, but
will be completely open to anyone with 222 MHz gear.
This is my project and experimentation "shoestring" 220 repeater. I obtained the Hamtronics boards from the Huntsville Hamfest fleamarket
a few years ago at a fairly cheap price; a Hy-Gain V3R antenna was a leftover from Long Electronics that I bought at H&H's table at Birmingham
several years ago for just a few bucks. So far, I have approximately
$100 invested in the repeater.
The goal is to ultimately have built my own equivalent
of the old Hamtronics REP-100 repeater, and I'm just about there except for the
PA and power supply.
Location
The repeater is coordinated for Spruce Pine, Alabama,
though I would like to locate it closer to Huntsville if a site is available.
Features
- This is going to be a plain-vanilla repeater with
little in the way of features. If the repeater can be located in a place
with coverage around Huntsville, it will be linked back to the 147.210
repeater in Spruce Pine.
Equipment
The repeater consists of the following equipment:
- Exciter: Hamtronics T51
- Power amp: None yet; will probably
homebrew a 10W amp
- Receiver: Hamtronics R220
- Controller: Hamtronics COR & Hamtronics
CWID
- Duplexer: None yet, but I'm looking for a
good deal on one!
- Antenna: Hy-Gain V3R
Controller Setup
There isn't much in the way of setup or control codes
on this machine!
The hang time is about 2 seconds. There is no
courtesy tone -- mainly because the Hamtronics COR doesn't have one -- but
also because as long as the transmitter is keyed up, whether by user input,
squelch tail, or CW ID, the TOT is running!
This means that the repeater must be allowed to
drop out COMPLETELY for the TOT to reset, but since there is no courtesy tone,
this behavior should be expected. So, use the squelch tail as an
opportunity to break in, but don't make a regular transmission until the
repeater drops.
The TOT duration is 2 minutes, 40 seconds. There
is no signal for time-out other than the repeater dropping. The ID is
not TOT controlled, so an ID may come due during timeout. If you believe
this has happened, feel free to do a favor for me and voice-ID the repeater
when it comes back up!
I don't have the CWID board set up yet, but I plan on
setting it up for "NV4B/R" at 20 WPM and 1000 Hz.
The ID will be completely unintelligent, so do not
expect a courteous ID (it may be dangerous to rely on the repeater's ID'er for
your personal ID timer).
Getting The Thing To Work
I had trouble rounding up documentation for quite sometime; the Hamtronics modules are 1980-vintage and Hamtronics no longer provides documentation.
The COR module docs seemed to be all but nonexistent until W4DEX in North Carolina provided me a JPEG copy in May 2007.
I had been having problems getting the exciter to work until very recently, and the COR documentation provided part of the clue -- the COR manual suggests a modification to key only the oscillator and leave +12V on the PA all the time. Normally, +12V is switched to the entire module, and when it is powered, it transmits.
After powering both connections, I was able to find that the crystal and/or crystal socket pins were loose, and once the connection was repaired, the transmitter worked fine.
The receiver worked the first time I powered it up, though the audio seems a bit distorted. I will troubleshoot it (if necessary) later, but it does seem to be working otherwise.
The COR is a different story altogether. I powered it
up for the first time recently, and it didn't work properly. Part of the
problem was two electrolytic caps and an LED were completely missing from the
board. Apparently reverse polarity had been applied at some point.
The "RCVR OPEN" LED was replaced, but didn't help much. One of the
electrolytic caps was for the TOT NE555. Without it, the COR board timed
out at power-up.
I am still having problems with the COR board keying the
transmitter with no COR applied (the RX LED even glows softly). It
shouldn't be too hard to troubleshoot; it's a very simple circuit.
5/27/2008: The NE555 on the PTT output of the COR board
was bad. A replacement works well. Also, the PTT mod on the
exciter needed to be re-done. The only problem remaining
to be resolved with the basic repeater is the receiver audio, which is
low and distorted.
6/11/2008: I received an original Hamtronics
diode-matrix CWID board from an eBay auction. I paid somewhat of a premium
for it to have the original Hamtronics ID'er, but in all honesty, even the
cheapest repeater ID'er available now is slightly more expensive. It is in beautiful condition and was programmed to
"WB6RHR/R." It worked fine on initial power up. The tone generator
had been modified for a higher frequency than I'd like (about 1500 Hz), so I'll
be undoing that mod to get it down a little lower.
6/24/2009: Finally, an update. I
tweaked the tuning on the transmitter to get the expected power out with good
stability. Previously the output appeared to be low, with a tendency to
drop off after key up. This was confirmed on a 220 wattmeter this evening
and fixed with some very minor retuning. Max out was 2.5W at 450 mA in; I
set it for 2W out with 350 mA in. I'll work on the receiver next.
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