Explain Sherwood Charts.

[KA5ROW]

Explain the Sherwood charts: higher or lower numbers which is better for each scale?

I am basing High Low numbers by comparing the IC-7800 to other radios. But the IC-7800 doesn’t appear the best in every respect. And for 12K it should.


1. Noise Floor: High or Low
2. AGC Threshold: High or Low
3. 100KHz Blocking: High or Low
4. Sensitivity: I assume Lower is better
5. Lo Noise spacing: I assume Lower is better
6. Filter Ultimate DB: High or Lower
7. Dynamic Range Wide: I assume higher is better
8. Dynamic Range Narrow: A assume higher is better

By knowing what to look for I can make a better decision on future radios like the Orion II as to the IC-7600, or whatever. I am not a contester or ever will be just rag chew. Current rig is a Pro|||

http://www.sherweng.com/table.html

[W6RZ]

1. Noise Floor: High or Low

A lower number is better. Since the numbers are negative, -140 dBm is lower than -135 dBm. Unless you have a very quiet location and only work 10 or 6 meters, this specification is not very important. With a reasonable antenna, band noise will almost always be higher than the receiver noise floor. However, this number is part of the dynamic range calculation, so it's always included.

2. AGC Threshold: High or Low

Lower is better. Ideally, you want the AGC to engage on all signals, but typically this is not possible. A lower number means the AGC engages on weaker signals.

3. 100KHz Blocking: High or Low

Higher is better.

4. Sensitivity: I assume Lower is better

Yes, lower is better. This is just another way to measure item #1.

5. Lo Noise spacing: I assume Lower is better

Higher is better for the LO noise number (in dBc/Hz). The spacing is just what it's measured at (almost all the current rigs are measured at 10 kHz).

6. Filter Ultimate DB: High or Lower

Higher is better. This is a measurement of filter "blow-by" (strong signals leaking through the stop-band of the filter).

7. Dynamic Range Wide: I assume higher is better
8. Dynamic Range Narrow: A assume higher is better

Higher is better. The difference between the 20 kHz and 2 kHz number is mostly a function of receiver architecture. Receivers with narrow roofing filters (or SDR receivers) perform better at 2 kHz spacing, while receivers with a VHF (like 70 MHz) 1st IF will perform worse (because narrow roofing filters aren't available at 70 MHz). This specification is much more important for CW operation. For SSB operation, it's very likely that transmitter IMD products (splatter) from other folks on the band will be stronger than receiver IMD products.

[N0AZZ]

On all the lists published QST,Sherwood and the early one in EU the one with the very best receiver is a mid priced Transceiver not the $10-14,000 ones but a $4900 one. That being a Yaesu FTDX-5000 starting at $4900 then there is a "D" and a "MP" model. I had a IC-7700 and when my FTDX-5000MP came I compared them side by side for 60 days and sold the Icom.

I think that Yaesu will be updating there FTDX-9000's with the 5000's receivers for certain and Icom will have to do something or fall even farther down the performance lists.

In the long run Yaesu has started something that will benefit us all with better radios and lower prices with competition between the big 3. All with a full sized radio loaded with of the best features and performance with 200w std. The ability to run the transmitter in Class A mode makes for a very clean signal even when running a amp with the FTDX-5000.

[N8YX]

On all the lists published QST,Sherwood and the early one in EU the one with the very best receiver is a mid priced Transceiver not the $10-14,000 ones but a $4900 one. That being a Yaesu FTDX-5000 starting at $4900 then there is a "D" and a "MP" model. I had a IC-7700 and when my FTDX-5000MP came I compared them side by side for 60 days and sold the Icom.

You look at the TS-590 specs yet?

Darned hard to beat that kind of performance and it's ~$2K.

[WB2WIK]

The IC-7800 was, at one time, towards the very top of the Sherwood Labs list. But it's technologically old and it's slipped down the list quite a ways as newer designs have surpassed it.

The '65 Mustang 289 used to be way up high on lots of lists, in '65-66. It would be about forty pages back from the front of the list today...

[N0SYA]

1. Noise Floor: I find -135 or so to be ideal, more sense just makes for a noisier no signal condition. That being said for quiet band conditions, or work on the upper bands, a -140 or higher mds can be of use.

2. AGC Threshold: I prefer low, and there are two main types of agc, a agc with range meaning weak sigs are weak in audio and strong sigs are obviously stronger as far as audio volume - wich is the most common in amateur usage, and a "military" agc where there is very little audio volume output difference between stong and weak signals.

3. 100KHz Blocking: 120dB is fine, more is better. As stated previously, contest/dx/serious cw work thrives with higher figures here.

4. Sensitivity: See noise floor. Lower is better especially for higher bands, but there's a point of diminishing returns where the nf is far lower than the average noise present in the band in use.

5. Lo Noise spacing: Closer to the carrier dynamic range is highly desirable here. A low noise oscillator can mean clean audio reproduction where a noisier carrier will mean more distortion inherent in the recovered signal audio, all else being equal.

6. Filter Ultimate DB: Some if systems blow out with leakage before their filters do, and this is a shame. 80dB is acceptible for ost use.

7. Dynamic Range Wide: 90dB and higher is better, but if you never operate near storng off freq sigs you will be ok with less.

8. Dynamic Range Narrow: 70dB or so is acceptible for most uses, higher here is much better however.

Bottom line is how you favor one rig over another. One rig may have outstanding specs and the praise of the ham radio gods yet have tiring audio to you, or you simply dislike the ergonomics or user interface and so use a rig with lesser specs. So run whatever you like. The above are merely my thoughts on the subject.

[W6RZ]

For noise floor, I found these numbers on this page:

http://openhpsdr.org/wiki/index.php?...opment_History

     Band         Ext noise dB above KTB        Noise figure dB    dBm @ 500 Hz

      80                    38                        28               -119
      40                    33                        23               -124
      20                    28                        18               -129
      15                    23                        13               -134
      10                    18                         8               -139

The external noise numbers are for the minimum atmospheric noise on each band. By having a noise figure 10 dB below the atmospheric noise, only 0.46 dB is added to the external noise floor.

[N0AZZ]

You look at the TS-590 specs yet?

Darned hard to beat that kind of performance and it's ~$2K.

Bought one thought I might use it in my Motor Home and for field Day owned it for 6 weeks and sold it. It really wasn't that much better than my IC-7000 and not large enough for a base radio. It was not even in the same class as the Yaesu's but not the money either.

[M0GVZ]

Bought one thought I might use it in my Motor Home and for field Day owned it for 6 weeks and sold it. It really wasn't that much better than my IC-7000 and not large enough for a base radio. It was not even in the same class as the Yaesu's but not the money either.

I own a Icom 7000 and a TS590 and a TS480 and the Icom isn't even in the same league as the TS480 when it comes to receiver noise and nearby strong signal handling, let alone the TS590. My friend has a fully filtered up FT2000D, a K3 and a TS590 and both the K3 and TS590 beat the FT2000.

Perhaps if you'd had it longer and learned to use it....

[KA4DPO]

The FT-2000 is an old design. The TS-590 has amazing specs for the money. I don't own one but did play with one at HRO and it really is quite good radio for the price.