[ARC5] Second Receiver Drift Test from KE6F SWAN 600R

Mon Nov 30 14:35:27 EST 2015

I do keep an eye on the ambient temperature with a laboratory standard electronic thermometer and keep an eye open for any shift that might result in an overall change in the results.  That's why I do the tests over the same time period each day and note the ambient for each test.  If there were a shift of more than a couple degrees I'd note that too.  The shop is insulated, but not heated.  The heat inside the radio cabinets is of course quite a bit warmer than the ambient, but that's part of the test to see how well the temperature compensation in the receiver's oscillators are dealing with the short an long term heat and heat soak.  Since all receivers have different enclosures and vent schemes that parameter is also part of the drift performance so taking internal case temperatures would not be of value when making comparisons of different receivers, but would of course be of value if one were making calculations for temperature compensation circuits in a specific radio.   That's another topic though 

	Thank you kindly for the comments though and it's fun doing this stuff and allows me to putter aorund with my test gear.

	73  Bob, KE6F

-----Original Message-----
From: Bill Cromwell <wrcromwell at gmail.com>
To: arc5 <arc5 at mailman.qth.net>
Sent: Mon, Nov 30, 2015 1:56 am
Subject: Re: [ARC5] Second  Receiver Drift Test from KE6F SWAN 600R

Hi Bob,

The first thing I noticed is your reported ambient temperature being 
different from the previous test. When you reported your previous test I 
did have a question about whether you monitored or attempted any strict 
control over the ambient temperature during the course of measurements. 
Tight control over the temperature might not be possible/reasonable but 
monitoring that factor is possible. In most ham shacks (including mine) 
the room temperature will vary by a few degrees depending on season, 
heating/cooling system cycling, etc. That is the kind of environment 
most radios will see so it only matters if we know how temperature 
changes relate to the results (operating frequency drift).

I have two shacks and in the garage some of the radios I have here show 
a small shift on the waterfall with electrical load changes on the 
circuit when my furnace blower kicks on and lowers the B+ slightly. 
There is a secondary slower shift as the tube heaters cool slightly. 
They go back the other way when the blower turns off. Battery operation 
or hard regulation of B+ and heater supplies eliminate that. Do you also 
monitor power line or power supply output voltages?

You probably don't want to redo the measurements to include additional 
factors and you should make all of the measurements under similar 
conditions - the same as you have been doing. I have been doing some 
experimental work to take advantage of passive solar heating here. I 
have been wandering around in rabbit holes while lowering energy use and 
that shows up on my energy bills. I have come to a point where I must 
deploy a system of temperature, light, and wind sensors and monitor all 
of those continuously with a computer if I hope to make further progress 
(Raspberry Pi and Arduinos are the heavy cavalry). For every "aha" 
moment new questions arise :)

Thanks for reporting the results your efforts and for taking the time to 
do the work.

73,

Bill  KU8H

On 11/30/2015 12:36 AM, Bob via ARC5 wrote:
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> Hi
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> 	Here is today's Receiver Drift Test on the SWAN 600R Custom
>
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> Tests were made in my shop at 56 degrees F
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> Signal source is an Agilent E4400B Signal generator with ovenized clock and a Rubidium calibration.  input signal level was kept at 500 microvolts to ensure a quiet signal environment. Tests taken on 10-29-15
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> 80 Meters
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> 4:00 pm	3.750000 MHz start run  Cold Start
> 4:20 pm	3.749998 MHz (-15 Hz change)
> 4:35 pm	3.749928 MHz (57 H change)
> 4:48 pm	3.749917 MHz (11 Hz change)
> 5:00 pm	3.749935 MHz (18 Hz change)
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> 40 Meters
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> 5:02 pm	7.150000 MHz start (one hour warm up during 80 meter run)
> 5:16 pm	7.149996 (-4 Hz change from start)
> 5:30	pm	7.150005 (+4 Hz change from start)
> 5:48 pm	7.150018 (13 Hz change)
> 6:00 pm	7.150037 (19 Hz change)
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> 20 Meters
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> 6:02	pm	14.200000 (Start two hours warm up accrued)
> 6:16 pm	14.200058 (58 Hz)
> 6:30 pm	14.200098 (40 Hz change)
> 6:48 pm	14.200134 (36 Hz change)
> 7:00 pm	14.200151 (23 Hz change)
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> 15 Meters
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> 7:05 pm	21.250000 MHz (Start three hours warm up accrued)
> 7:30 pm	21.250005 (5 Hz change)
> 7:48 pm	21.250020 (15 Hz change)
> 8:00 pm	21,250024 (4 Hz change)
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> 10 Meters
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> 8:03 pm	28.800000 MHz (Start four hours warm up accrued)
> 8:20 pm	28.800084 MHz (84 Hz change)
> 8:35 pm	28.800133 MHz (49 Hz change)
> 9:00 pm	28.800228 MHz (95 Hz change)
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> Once again I am somewhat surprised at the outcome.  I did my best to control the test methods.  The environment was somewhat colder than one might expect in a ham shack by perhaps 5-8 degrees, but all things considered, the SWAN 600R did quite well and represents a receiver that would do well in a modern SSB environment and perhaps even some RTTY stuff. perhaps the SWAN 600R's reputation as a drifty unit was based on the SWAN line of SSB transceivers where heat cycling was a major factor.
>
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> Comments invited.  I  Hope to get the Collins 75S3B done tomorrow and during the same time frame to keep the ambient temperature in the same range.  The first test on 80 Meters was started after a 5 minute tube warm up as was done in the NC303 test.  Once again I am not trying to gore anyone's favorite beast, just trying to sort out the myth from some reality.  Drop tests were not made as it's too damn hard to control that type of test.  The SWAN did exhibit some microphonics, but not enough to discourage its use.
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> 73  Bob, KE6F
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> NC303 Update: Minimum discernible signals taken but not listed earlier. Taken in narrow BW position.
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> 80 Meters MDS 40 nV
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> 40 Meters MDS 40 nV
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> 20 Meters MDS 48 nV
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> 15 Meters MDS 62 nV
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> 10 Meters MDS 100 nV
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