[Boatanchors] HP 606 vs. 608

Wed Feb 11 23:23:35 EST 2009

Yeah Don, but you didnt mention one radio Id own.

Now the K-3 has me intrigued.

I regularly run IMD tests on my better boatanchors and with the MDS 
often in the -135 to -140 dB range low phase noise is very important to 
me.

You didnt specify an offset but the plot Im looking at is 114.8 dB at 10 
kHz, not good at all. At 500 Hz its -72dB...YUK! Id have to be out 
around 60 kHz offset before the phase noise meets the receiver floor in 
a R-390A or many of my front end conversions of other receivers.

Yeah, maybe Im an exception but I enjoy using something as old as a 1935 
HRO in a contest or digging for DX on 80/40M. My main HF rig is a highly 
modified TS-940 but when the going gets tuff an also highly modified 
75A4 that Ive had since 1965 is used. Nothing Ive ever owned or tried 
can beat it for "digability"

Carl
KM1H

----- Original Message ----- 
From: "Don Buska" <dbuska at wi.rr.com>
To: "Carl" <km1h at jeremy.mv.com>
Cc: <boatanchors at qth.net>
Sent: Wednesday, February 11, 2009 9:24 PM
Subject: Re: [Boatanchors] HP 606 vs. 608

> Hi Carl,
>
> I don't consider -114dbc/hz bad phase noise for the purpose it serves, 
> especially considering the use in working on old BA's.  Naturally a 
> non-synthesized oscillator is going to be much lower in phase noise 
> (Just don't tap the table, hi).  Are there better synthesized 
> generators, you bet and for those you'll pay for it.  However, I don't 
> use it to do receiver measurements that would be expected when running 
> comparisons on the latest and greatest products being produced today. 
> For working on old BA's and performing frequency setting, IF alignment 
> and general sensitivity measurements I'll take the 8656 any day of the 
> week.  It serves it purpose admirably and with great ease of use.
>
> "You probably wouldn't notice it since the IC-745 is in the same phase 
> noise class. Its one of those radios that comes up "Phase Noise 
> Limited" in IMD tests. ".  Sure and you will also run into this 
> performing measurements on the Yaesu FT-1000, FT-2000,  Elecraft K2, 
> etc.  These are ham rigs, not government spy radios, hi.
>
> 73
>
> Don N9OO
>
>
>
>
> Carl wrote:
>> The HP-8656 and 8656A have the 2nd worse phase noise in HP's history 
>> with the #1 position being the 8660/8660A. There is a good reason 
>> they are so cheap as no serious ham shop would have one. Many on Epay 
>> are on the 2nd or more rebound since they left commercial labs where 
>> the problems werent relevant to their use.
>>
>> You probably wouldnt notice it since the IC-745 is in the same phase 
>> noise class. Its one of those radios that comes up "Phase Noise 
>> Limited" in IMD tests.
>>
>> Before anyone makes a mistake in their choice I suggest joining the 
>> HP Yahoo forum, ask questions, and look in the files for several 
>> plots.
>>
>> hp_agilent_equipment at yahoogroups.com
>>
>> The non synthesized HP-8640B and its military HP-8640B Opt 323 aka 
>> AN/USM-323 variant are still the standard in the affordable category. 
>> The HP-8657A is acceptable for many uses but its price reflects its 
>> acceptability status.
>>
>> Carl
>> KM1H
>>
>>
>>
>>
>>
>> ----- Original Message ----- From: "Don Buska" <dbuska at wi.rr.com>
>> To: <boatanchors at qth.net>
>> Sent: Wednesday, February 11, 2009 4:07 PM
>> Subject: Re: [Boatanchors] HP 606 vs. 608
>>
>>
>>> I understand our love for the BA's, but for me I want my test gear 
>>> to be
>>> the "standard" in my lab.  Since the early part of this decade 
>>> (after
>>> the DOT COM bust) newer used test instruments have really taken a 
>>> big
>>> price hit.  With our latest economic problems this has only added to 
>>> the
>>> amount of equipment out there at very reasonable prices.   It may be
>>> time to move out that 1950/60's test gears and buy some 1980's 
>>> stuff.
>>>
>>> In my case I bought an HP 8656A Signal Generator off eBay a couple 
>>> of
>>> years back for around $300.  What it gives me is a modern 
>>> synthesized
>>> generator that does 100kHz (see below) to 990MHz with internal AM/FM
>>> modulation.  Using the internal frequency standard I only 
>>> experienced
>>> about a 1kc error max across the whole frequency spectrum.  Also, 
>>> even
>>> though it is rated to have a lower frequency limit of 100kc it will
>>> accept lower frequencies entry.  I just aligned my SX-115 50kc IF 
>>> using
>>> it and the frequency and output levels were spot on.  I used the HP
>>> 8656A and selected external AM modulation supplied by the output of 
>>> my
>>> HP 3325A function generator sweeping from 10Hz to 10KHz,  and then
>>> monitoring the IF output on an Advantest TR4171 spectrum analyzer 
>>> (the
>>> only SA I know of that also has a Hi-Z input channel).  Immediately 
>>> you
>>> can see what a difference it makes to fine tune IF alignments to get
>>> symmetrical sidebands on each side of the carrier.  I quickly found 
>>> out
>>> that peaking the IF's for the carrier frequency won't do that. 
>>> Actually
>>> I quickly discovered my cause of a noticeable difference between my
>>> signal levels under AM-USB and AM-LSB on my SX-115.  I would have 
>>> been
>>> head-scratching for days if all I had was an old RF generator and 
>>> VTVM.
>>> This is a perfect setup for performing stager tuning of IF's if that 
>>> is
>>> necessary aka HQ-170-180's.
>>>
>>> Bottom line is many of us are willing to invest thousands in our
>>> stations, but then only a couple hundred, if that much, in test 
>>> gear.
>>> Good modern RF generators can be had for well under $500 if you look 
>>> for
>>> them.  Sweeping audio generators for much less and good spectrum
>>> analyzers for a bit more.  Also, another excellent signal generator 
>>> is a
>>> transceiver.  My older Icom IC-745 has a transverter output which 
>>> simply
>>> operates the rig minus the final amplifier.  The RF output control 
>>> still
>>> works so I can generate an RF signal from 1.5MHz through 30MHz at a
>>> level up to 50mW.  I think IC-745's sell for around $300 these days. 
>>> A
>>> good signal generator that can also make QSO's, hi.  Plenty of the
>>> high-end solid-state function generators, with sweep, will go to 
>>> 20MHz
>>> and are great for IF alignment too.  Don't go to the surplus 
>>> equipment
>>> houses, keep your eyes open on eBay.
>>>
>>> BTW, I gave my two 608C's away a couple of years back.  I'm glad I 
>>> don't
>>> have to fool with those anymore.  I'm not getting any younger and if 
>>> I'm
>>> going to pull a muscle it will be on an BA transmitter and not my 
>>> test gear.
>>>
>>> 73 es take what you want and leave the rest.
>>>
>>> Don N9OO
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>>
>> 