Thanks Mike. We had plenty of separation and bandpass filters.
The suspicion is that the radio hasn't been smoked as a result of the
contest, but there is definitely a receive fault. I am trying to
determine where to look.
Listening to broadband white noise on 160m from local high voltage
power lines, the Main Rx S-meter registers s1, where as Sub Rx registers
s6-7, which is more like what I am used to. Looking at the cct diag, the
paths are common until a hybrid coupler and then the main Rx signal goes
into the 1st mixer. so the problem may be around here. I wondered if
anyone has experienced this before.
Mike K9MI wrote:
> Since the ARRL has the new "F" class (operating from an EOC) we have been
> operating from our EOC where the antennas for the 2 rigs we use are within
> about 40ft, and at the same height. Testing shows that around 3 watts is
> seen on the wattmeter, using one antenna hooked to a dummy load and watt
> meter. We use coaxial stubs and now you can see a very very small movement
> on the watt meter. So, we use the stubs every year, although the bandpass
> filter I'm sure would be better, more elegant way to approach the problem.
> Ice and Dunestar make these and Dunestar has an "all band" box, but I'm
> thinking it is around $600. We're just using 100 watts. I have not purchased
> it, but George of Inrad has written a book on how to tackle the problem of
> interstation interference. That is one of many things on my wish list.
> 73, Mike K9MI
> ---- Original Message -----
> From: "dsthill" <email@example.com>
> To: <firstname.lastname@example.org>; <email@example.com>
> Sent: Monday, December 11, 2006 15 28
> Subject: Re: [Yaesu] Ft1kMP loss of receive gain
>> Hi Chris
>> As someone who zapped an FT1kmpMK5 about a year ago, I think it's easier
>> than you think. I hope you were using bandpass filters on this rig. It's a
>> common mistake I think to not use them in some situations. I think though
>> a multi-transmitter setup, it's very important that each rig has necessary
>> I've actually measured 1 to 5 watts at the end of some of my coax cables
>> when transmitting on another antenna.
>> When I did my repair, it was just a single diode or a pair that were bad,
>> but it was the labour that was "expensive" - $200+ for labout against $5
>> Hope it's not that bad!!!
>> Dean - 8P6SH
>> -----Original Message-----
>> From: firstname.lastname@example.org [mailto:email@example.com]
>> Behalf Of G3SJJ
>> Sent: December 11, 2006 5:48 AM
>> To: firstname.lastname@example.org
>> Subject: [Yaesu] Ft1kMP loss of receive gain
>> I am noticing a receive loss of around 10-12 dB. I have checked Antenna
>> B and receive antenna inputs. They are the same.
>> What I do notice is around 2-4 s units difference in indicated signal
>> strength between main and sub Rx, which would indicate the problem is
>> after the 1st mixer.
>> We recently used the radio as a spotter in CQWW CW at G5W . Whilst it is
>> unlikely, we could have zapped the front end somewhere.
>> Anyone got any thoughts?
>> Chris G3SJJ
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