I'm glad you mentioned that about channel 11 last week. During the 222
sprint I noticed a lot of noise in a certain direction. I put the TinySA
on the antenna and noticed I got new neighbors on channel 11 and 12.
That must have happened with a frequency move last year. They're on a
mountain about 20 miles from me, and I'm on a mountain as well. I guess
I'll have to build a bandpass filter to put in front of the transverter.
No pre-amps here.
73,
--Alex KR1ST
FN21fk
On 2021-04-18 12:47, Dave Olean wrote:
Don't forget that Tuesday will be the first activity night for 222
MHz. Well, not really the first, but at least an attempt to build some
local activity all over the country. I will be on looking for
contacts and using the ON4KST page along with HB9Q if there is
activity there as well. I encourage everyone who has 222 MHz to make
an appearance and we will see what happens. Conditions here in the NE
are pretty punky now with no tropo condx in sight anywhere, but the SE
always seems to have some tropo. This Tuesday, it will be slightly
good in the gulf area. As the warmer wx approaches, we can expect
better results on 222, so lets try every Tuesday evening.
I went up to the shack today to look into my Channel 11 TV overload
situation. When an antenna is aimed at 219 degrees, CH 11 is in the
pattern and overloaded something. I suspected the preamp. I had it
all working fine last fall, but the front end got wiped out by a
winter snow storm with static, and I swapped out the preamp with a
replacement. Now I had the noise and I suspected the preamp, so I
changed the preamp and put the old one back in after I repaired it. It
is an HP AT10135 GaAsFET. The snow static had blown the FET gate along
with one of the source bypass capacitors! After re building the front
end, I put it back in line, and that noise seems to be gone. I see
noise variations now as I rotate the beam, but the variation is
slight. It was 3 S units before! It looks like the overload is gone
and ,my LVA antenna now seems to hear OK with stations at 218 degrees
or so. The K1IIG beacon is on that heading, so it is a good test.
While I was doing these tests, my receive just died. It turns out the
transverter had gone in to transmit all by itself. I unplugged the
keying line and it remained in a transmit state. I brought it down to
my house and opened it up. I measured 1.5 ohms to gnd on the PTT
input. Poking around there made the problem go away. Now I see 13
volts there when un keyed. I suspected a bypass cap had gone bad, but
it seems fine. Heating and cooling it has no effect. I suspect I had
some "schmutz" causing the problem....most likely steel wool strand or
? Anyway, I will put everything back together so I will be ready for
Tuesday evening.
Remember APRIL 20 on 222.1 MHz CW, SSB, MSK144, FSK441, JT65B, FT8.
I will draw the line with modulated oscillators and spark rigs.
Dave K1WHS
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