[UK-CONTEST] What is the best VHF Radio
Jiri Culak
Jiri.Culak at lwss.co.uk
Tue Sep 9 08:50:30 EDT 2008
It is difficult to judge radio by only one parameter.... Therefore the
question(s) might be:
What is best VHF radio for:
a) Weak signal modes (EME,MS,IONO,FAI etc.) with no strong signals - in
that case you might go for good LNA which will reduce theoretically
noise figure of your out of the box radio. 847 with MGF or CF300 device
will do that job.
b) for contesting where weak signal sensitivity with selectivity and IP3
stop bands, along with "being nice to others" and having clean TX with
little phase noise (if you will use PLL/DDS based radio)
c) for FM repeaters and satellite work - usually sensitivity and cross
band RX/TX means that wide band preamps puts thouse radios out of league
of contesting.
(FT736s are good radios overall....or lots of OP thinks, but that
depends too on point of view and what you want to do with them)
4x4 does not mean it's good off road, GTi means nothing to performace,
even both will do school runs :-D Radios are pretty much same, if you
want formula one or hard off roader, you modify what ou got or better,
built station yourself from components which are proven by time and
masses.
PS: One highlight... one un named contest station deep on EU was running
4cx15,000 PA and was driving it with CW only crystal oscillator with 1W
output, into few hundred watts 48V solid state brick, and nobody ever
complained or noticed from spurious emissions, on the other hand, I
remember having big problems with another station in OK1, 200km away but
in direct sight WEST of me, running IC706 with 200W overdriven PA with
switch mode supply, causing s9 noise 144-146MHz a FM modulated
overcompressed signal....
Jiri
Quick advise... get yourself cheap MML144/28 transverter, by pass
preamp, put hardline coax and have less than 1dB loss between antenna
and RX, and use HF rig to hear stuff...(847 will do) and let me know if
you noticed any difference, I am sure you will.
Subject: Re: [UK-CONTEST] What is the best VHF Radio
The sensitivity of the IC7400 is not bad - I reckon a Noise Figure of
about 3 dB, but I don't think this is an issue, as for serous use you
have to have a mast head preamp anyway.
John G3UUT
Darrell G0HVQ wrote:
> Interesting reading, speaking as a HF/VHF contester and keen VHF op.
>
> Whilst I am a fan of the IC7400, having owned one and used it in HF
and VHF
> contests for a couple of years, I only consider it 'adequate' on 2m
(and
> HF).
>
> On 2m, I have been fortunate to run it alongside an old Icom IC 251E
with
> Mutek front end in several 'lifts' - it doesn't have all the bells and
> whistles, but is significantly more sensitive than the 7400.
>
> A few people I've spoken to think highly of the 847 as a V/UHF radio.
>
> It'd be great if one of the big manufacturers produced a
high-performance
> V/UHF radio, but like Joh says I think those days are gone due to lack
of
> demand - you only had to listen to 2m yesterday during the biggest
contest
> of the year. I've got a reasonable station and struggled to make more
than
> 40 QSOs in 6 hours.
>
> I think next time I'll got for a higher-performance HF/6m radio and
get a
> decent transverter for 2m.
>
> 73
> Darrell G0HVQ
>
>
>
> ----- Original Message -----
> From: "John F Wilson" <UK-Contest at grebe.plus.com>
> To: "UK-Contest" <uk-contest at contesting.com>
> Sent: Monday, September 08, 2008 3:29 PM
> Subject: Re: [UK-CONTEST] What is the best VHF Radio
>
>
>
>> Neil,
>>
>> I reckon the IC7400 despite one or two issues, is hard to beat, on
all
>> round performance, strong signal handling and trasmit noise close to
>> carrier. The problem is that it only covers HF, 50 MHz and 144 MHz.
>> Its high time ICOM produced a DSP VHF/UHF rig as a successor to the
>> IC910 but I suspect they won't due to the smaller market than for HF
rigs.
>>
>> On your original point, my feeling is that with the attenuator in and
>> the preamp off, it was the transmitted signal that was at fault
unless
>> you just turned your preamp off by removing the supply to it without
>> switching it out of circuit in which case it might be that if the
signal
>> was strong enough it could still be driving the off amplifier device
>> into non-linearity.
>>
>> 73 John G3UUT
>>
>> Ian Burns wrote:
>>
>>> Neil,
>>>
>>> The Javornik II can be found here
>>>
>>> http://lea.hamradio.si/~s53ww/xvrt/xvrt.htm
>>>
>>> The page also shows some screen shots of the transverter o/p
indicating
>>> why you don't want to use it. With the PA turned off, depending on
the
>>> drive control setting (anything over about 1/4 is bad) the o/p has
>>> spurii about 45dB down from the main carrier. These spurs move in
and
>>> out with respect to the main carrier as the rig is tuned across the
band
>>> and are offset anywhere from zero to several hundred KHz from the
>>> carrier. Filtering is not an option.
>>>
>>> When you have seen how bad the TVTR o/p from the FT1000MP is you
won't
>>> want to use it to transvert to any band...
>>>
>>> As Jiri says a pad on the main o/p works well and is clean.
>>>
>>> 73
>>> Ian
>>>
>>>
>>> G3RIR wrote:
>>>
>>>
>>>> Ian,
>>>>
>>>> Thanks for the response. I have never heard of Javornik perhaps you
can
>>>> let
>>>> me have a link.
>>>>
>>>> I have an FT1000mp as well as my FT847 and have a DEM transverter
for
>>>> 432
>>>> which was used with the FT1000mp. I moved to the FT847 for
contesting on
>>>> 432
>>>> as there are not too many very strong signals on 432 from our NFD
>>>> location
>>>> (G3SDC/P on the Norfolk coast (JO02st)) and it is much more
convenient
>>>> and
>>>> smaller that the FT1000mp etc!!
>>>>
>>>> I have recently been active on 144 and that is where the FT847
might not
>>>> have a robust enough receiver. However I found only one signal
>>>> splattering
>>>> during the weekend from my home qth in IO92 so I am not blaming the
rx
>>>> just
>>>> yet.
>>>>
>>>> What did you find wrong with the FT1000mp transverter output? Could
it
>>>> be
>>>> cleaned up with filtering? When using the FT1000mp for a
transverter I
>>>> switch off the pa completely from inside the little top lid as this
is
>>>> safer
>>>> than someone accidentally running too much power from the pa into
an
>>>> attenuator.
>>>>
>>>> Neil, G3RIR
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: uk-contest-bounces at contesting.com
>>>> [mailto:uk-contest-bounces at contesting.com] On Behalf Of Ian Burns
>>>> Sent: 08 September 2008 09:13
>>>> To: uk-contest at contesting.com
>>>> Subject: Re: [UK-CONTEST] What is the best VHF Radio
>>>>
>>>> I can thoroughly recommend the FT100MP and Javornik II transverter
>>>> combination. The receiver is not totally bomb proof but is
noticeably
>>>> better than my FT847. We used the setup at G0FBB in the 2m trophy
this
>>>> weekend and had no real problems despite some very loud signals on
the
>>>> band.
>>>>
>>>> The only drawback of this combination is that the transverter
output of
>>>> the FT1000 can be too dirty to use on a crowded band. It's a fair
way
>>>> off the VHFCC recommendations of -100dBc... The main o/p is clean
enough
>>>> to use via a suitable attenuator though.
>>>>
>>>> 73
>>>> Ian.
>>>>
>>>> Dave wrote:
>>>>
>>>>
>>>>
>>>>> At 20:21 07/09/2008 +0100, G3RIR wrote:
>>>>>
>>>>> There is a useful comparison of HF Tcvrs here
>>>>> http://www.df9ic.de/tech/trxtest/trxtest.html
>>>>>
>>>>> 73 Dave G4RGK
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Earlier today I reported to a station on 144MHz that his signal
was
>>>>>> very
>>>>>> wide. I could hear splatter about 12kHz either side of his
signal.
>>>>>>
>>>>>> I turned off my mast-head pre-amp, switched in an attenuator and
>>>>>> turned
>>>>>>
>>>>>>
>>>>>>
>>>> my
>>>>
>>>>
>>>>
>>>>>> beam side on so that I only had s7 registered on my s-meter. The
>>>>>> splatter
>>>>>> was still noticeable.
>>>>>>
>>>>>> The station concerned said he was definitely not over-driving
>>>>>> anything.
>>>>>>
>>>>>>
>>>>>>
>>>> He
>>>>
>>>>
>>>>
>>>>>> asked what receiver I was using and on being told it was an FT847
he
>>>>>> suggested that it was my receiver at fault. This may of course be
the
>>>>>> problem but he wasn't the only loud signal on the band but was by
far
>>>>>> the
>>>>>> widest.
>>>>>>
>>>>>> What are the group members' views on the FT847 in handling such
>>>>>>
>>>>>>
>>>>>>
>>>> situations
>>>>
>>>>
>>>>
>>>>>> and indeed what is the best receiver around for 144 and 432?
>>>>>>
>>>>>> I am also interested to know what is the specified noise figure
for
>>>>>> the
>>>>>> FT847; of course the manual only refers to sensitivity!
>>>>>>
>>>>>> Neil, G3RIR
>>>>>>
>>>>>> _______________________________________________
>>>>>> UK-Contest mailing list
>>>>>> UK-Contest at contesting.com
>>>>>> http://lists.contesting.com/mailman/listinfo/uk-contest
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>>
>>>>>
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