[Premium-Rx] Fw: "Best Radios"

K0DAN k0dan at comcast.net
Sat Nov 10 21:59:43 EST 2007


Michael O'Beirne (G8MOB) has asked me to forward this to the reflector...he 
has sent his email it a few times previously, but due to unknown forces 
(spam filters, antivurs software, cosmic rays or black holes), he post never 
made it to the group. More food for thought on the ideal receivers and the 
search for the holy grail.

Regards,

Dan


FYI from G8MOB

----- Original Message ----- 
From: Michael O'Beirne
To: PAUL KLUWE
Sent: Wednesday, November 07, 2007 10:56 PM
Subject: "Best Radios"

Good evening guys

A lot of us are asking the wrong question.  No one receiver is "best" or 
ever will be.  Ought we not to be asking best for what mode and best for a 
particular operator?

How do you even define "best"?

On a data mode you probably measure on the Bit Error Rate.  Many automated 
commercial and military systems uses this for selecting the best channel and 
can track the diurnal changes in the MUF very successfully.  Audio quality 
is unlikely to be important.

For casual listening you may find audio quality supremely important (I do). 
You select on what your ears tell you.  Any receiver giving a total harmonic 
distortion in excess of 1% at the headphone socker is, for me, unacceptable. 
I have the test gear here to do the measurements, and the figures usually 
back up what my ears have already said

Any trace of digital hash is such bad news.  That rules out the original WJ 
HF1000 for me!

On this criterion, the very best audio quality is the little known Phase 
Track F1-2, as once used by the BBC and CBC for rebroastcast purposes.  But 
it's crystal controlled - though that's ideal if you want 9 pre-selected 
channels.  THD is under 0.5% from 50Hz to 3,500Hz.  Phase noise from the LO 
is almost non-existant

Next best for AM audio quality in my experience are
1.    Eddystone 1650 bareback (excellent synchro);
2.    RA1792 with the add-on Surrey Electronics ISB/DSB/AM demodulator using 
a phasing system;
3.    Plessey PR2280.

The Racal 3701 sounds very nice but in my view gives too much audio hiss - 
though you can reduce to acceptable limits that with an external audio 
attenuator and a good analogue audio filter.

If you want to listen to noisy AM in SSB mode, you will need a supremely 
good SSB filter.  Most conventional filters are too narrow and give rise to 
very poor phase distortion, which you can detect if you are at all musical. 
Old mechanical filters are the worse. I found the R390A sounded just 
horrible.   The 2.3kHz ham ones are also dreadful.  The 2.9kHz wide ITT 
crystal filter in the RA1792 is about ideal.

Particularly good filters are the phase compensated ones.  My experience of 
these are those sometimes installed in the Marconi H2540 and H2541, 
primarily for fast data point-to-point links where phase errors are a big 
no-no.  They sound fabulous on AM signals taken as SSB.  And so they should. 
The ex-factory UK price from Marconi in the 1990s was around £350 for the 
USB and over £1,200 for the LSB one, plus VAT of course.

The receiver portion of the military PRC320 SSB transceiver (made by 
Plessey) gives excellent receive quality on all modes.  You may know that 
the SL600 series of ICs were specifically designed for this receiver in the 
1960s.  The Philips  PRC2000 transceiver is as good or better.  It uses the 
complex Weaver third method phasing system of selectivity and has no 
distorting filters, yet gives a very acceptable shape factor.

Allied to this is an IF shift so that you can place the filter over the 
important part of the signal without affecting the tuning.  Too many older 
PR radios have none, though it is possible to build an add on unit fed from 
the IF output.

That's enough on audio quality.  What about "operability".  This is a highly 
personal business.  For me good operability demands one switch-one function. 
That eliminates most oriental black boxes.

The panel must be arranged neatly and logically.  No tiny panels - proper 19 
inch jobs - and not too crowded.  The USB switch must lie above the LSB 
switch.  The switches must be man sized, not the stupid tiny things Yaesu or 
Icom make.  I demand a quality push feel or click feel.

The knobs must feel right, and no concentric controls unless of dissimilar 
diameters.  I vote for the Raytheon knobs as used by General Dynamics and 
many others, and the Berco knobs found on the RA1772 series.  The Sifam ones 
on the RA1792 and 3701 series are nice too.

The colour of the panel is important for me.  Crowded black knobs on black 
panels defeat my eyes.  So no Jap kit!  Our Navy specify light battleship 
grey panels, and in my view it's a very calming colour.  RA17 panels are a 
delight.  I also like the older HP pale yellow panels.

Good analogue meters are important too.   Decent quality meters by 
Bach-Simpson, Honeywell, Sifam,  et al are important.  The meter on the 
HF1000 struck me as being very cheap and cheerful, and you'd think WJ really 
could do better.

The tuning feel is vital.  We UK types take for granted the super smooth 
finger tip weighted tuning on most old Eddystones and the SP600.  Most 
Collins receivers just feel so dead, and the R390 is indescribable in this 
context (though it's a very fine receiver in other areas).  But the very 
best tuning "feel" is on the RA1772 and RA3701.  if you undo the brake screw 
on the 3701 and give the knob a good flick, it will still be turning 15 
seconds or more later, though that is too free-running for me.

Allied to the tuning there should be a Bargraph either built in or as an 
slim 19 inch adaptor.  The best is still Racal's MA1105.  Think of a one 
line spectrum analyser of 104 LEDs.  Makes tuning a carrier a total sinch. 
Simplified versions are built in to the E1800 (I believe) primarily for 
tuning data signals.

The AGC feel is vital.  Pops at the start of a syllable or a CW character 
are not acceptable and will drive you mad, but are still common.  I can't 
speak for WJ, Harris, Cubic or similar American goodies, but so far the 
nicest sounding AGC I have encountered is on the Phasetrack F1-2 and RA1792.

So what's ideal?  Probably the Standard Radio CR91 panel with its Sifam 
meter but a bigger LED frequency display, Berco knobs, the audio quality of 
the F1-2, the IF selectivity of the 8711A, the build quality of the 
8718A/MFP.  Now you are getting somewhere.  Then throw in a tracking 
preselector using small relays (not diodes) and a reasonable IP (say over 
+25dBm at 20kHz signal spacing) and you are in with a start.

End of the wish list.  Where is this receiver?

73s
Michael
G8MOB 



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