Re: Hamtronics 224MHz Repeater Kits
>-- Eric <[EMAIL PROTECTED]> wrote:
> I've had three of them. They've all been crap in high RF
> environments (mountain top). Also, they have issues like
> flakey squelches, difficult to align front ends, poor audio
> frequency response, etc. In fact, I'm a little surprised
> you've found them to be satisfactory. I know two other guys
> up here that have tried them over the years and hate 'em for
> many of the same reasons.
Let me try this again... I typed out a big reply and hit a
keyboard key only to see my first post go off to never-never
land.
I had all the same problems. My first all Hamtronics 224 MHz
Repeater went right next to a 3kw fm broadcast transmitter in
Vacaville. Of course any part of the orignal Hamtronics cor-1
or cor-2 circuit not properly rf bypassed went active and locked
the tx on the first time I keyed it from the bottom of the Hill.
So I had to learn how to bypass everything with disc caps and
properly cover/seal any holes in the metal chassis.
The receiver squelch is also mushy, part of the hamtronic rx
circuit, which is based pretty much out of the Motorola Data
Book for the MC-3357 or MC-3359 chip they used at the time. I
know they're using a different receiver combo chip in the newer
generation receivers, so you'd have to look up the data sheet
to begin changing the squelch circuit around. Our good friends
at Spectrum Actually have/had the best squelch circuit for the
above name chips.
I removed or changed the squelch hysterisis resistor(s) to make
the operation more crisp (think I actually took that resistor
out or changed it to a very different value.
I also had put an additional helical resonator preamp on the
front of the receiver to help protect the front end. At the
time, Hamtronics was selling a preamp backed helical front end,
which I liked quite a bit for the high IMD protection of the
bipolar (if memory serves me right) device. Now they offer a
GasFet version and I have no idea what the 3rd order values are
for the GasFet Circuit. You could also order (if still available)
the Toko Helical Filters direct from Digi-Key and "roll your
own" if you want the more hardy bipolar device or an even better
Phempt.
At the time, Hamtronics also offered a non preamplifed helical
front end. Though the helicals are relatively wide band width,
the assembly in front of the receiver was more than enough to
remove the blocking issue, provide dc grounding and keep the
receiver front end under control.
The duplexer you park in front of the repeater also makes a
difference. I had decades of great operation using a 4 cavity
Telewave BpBr Duplexer.
With a homebrew 35 watt pa (actually the Hamtronics Repeater PA
built from the kit). I traded it away about 4 years ago in a
weak moment, wish I hadn't... it's out there some where, probably
still working just fine if the new owner kept the golden screw
driver out of the circuits.
>
> Oh well, it'll give us another thing to talk & compare
> notes about in Dayton.
> Looking forward to seeing you there.
> eb
Looking forward to seeing you and everyone else at Dayton, but
first IWCE in Vegas for two days on Tuesday and Wednesday.
chow for now
skipp
>
> ----- Original Message -----
> From: "skipp" <[EMAIL PROTECTED]>
> To: "Eric" <[EMAIL PROTECTED]>
> Sent: Thursday, May 11, 2006 1:44 PM
> Subject: Re: Hamtronics Repeater Kits
>
> > Hi back,
> > Funny you're having such trouble with your 224MHz Repeater.
> > I've run a number of Hamtronics Kit Repeaters and equipment
> > combinations through the years with nothing but great results.
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