Traditional radio VS FlexRadio

[RocketNJ]

There are superhet SDRs, so you really have to distinguish between an all analog hardware radio vs SDR, which comes in many different flavors.

Correct. Yaesu FTdx-101D is an SDR receiver with IF filters in front of it. Same with the Elecraft K4HD (expected by end of year). Where you will see a benefit of those radios over straight SDRs is in a multi/multi or Field Day environment. Unfortunately (if you read the reviews) the ergonomics of the 101D are less than good (being kind).

I have a Flex 6600M I will be using at Field Day this year. The second station will be a 6600 and the third again will be a 7300. The 7300 will get nailed with overload but the two 6600s should be fine @ 100 watts due to the 7th order bandpass filters. The 7300 TX phase noise is not too good for a multi/multi configuration so we will make that station use antennas further away from the other two stations. Also the 7300 will not be allowed on the same band as the other two stations.

 

[prcguy]

Same as the Elecraft K3S sitting in front of me and that superhet design is partially responsible for the high performance a K3 is known for. The very first SDR radios ever designed in the 80s were superhet because of A/D frequency limitations. They had to downconvert most frequencies to be within the operational frequency range of the A/D converter.

Correct. Yaesu FTdx-101D is an SDR receiver with IF filters in front of it. Same with the Elecraft K4HD (expected by end of year). Where you will see a benefit of those radios over straight SDRs is in a multi/multi or Field Day environment. Unfortunately (if you read the reviews) the ergonomics of the 101D are less than good (being kind).

I have a Flex 6600M I will be using at Field Day this year. The second station will be a 6600 and the third again will be a 7300. The 7300 will get nailed with overload but the two 6600s should be fine @ 100 watts due to the 7th order bandpass filters. The 7300 TX phase noise is not too good for a multi/multi configuration so we will make that station use antennas further away from the other two stations. Also the 7300 will not be allowed on the same band as the other two stations.

 

[alcahuete]

I have a Flex 6600M I will be using at Field Day this year. The second station will be a 6600 and the third again will be a 7300. The 7300 will get nailed with overload but the two 6600s should be fine @ 100 watts due to the 7th order bandpass filters. The 7300 TX phase noise is not too good for a multi/multi configuration so we will make that station use antennas further away from the other two stations. Also the 7300 will not be allowed on the same band as the other two stations.

We have run 7300s and 7610s for Field Day and contests for several years. Never have overload issues. Heck, I run that combination at home @1500w each for contests and don't have overload issues. I use a bunch of external bandpass filters (like you should anyway), and you don't even know the other station is there.

 

[RocketNJ]

Keywords are external bandpass filters.

Without and the 7300 receiver is susceptible to overload and the TX phase noise is pretty ugly

 

[prcguy]

The 7300 TX phase noise might be a bit high for operating same band, same site on field day but its very good compared to many radios out there like the Icom 7600 or the Yaesu FTDX1200. The Yaesu is brutal to anyone +/- 5KHz either side of them and on a spectrum scope they stand out like a big Christmas tree.

All the 7300s I've heard seem very well behaved on tx with their signals tightly within the specified pass band when viewed on a spectrum scope.

Keywords are external bandpass filters.

Without and the 7300 receiver is susceptible to overload and the TX phase noise is pretty ugly

 

[alcahuete]

Keywords are external bandpass filters.

Correct...you know...like all the major contest stations and hams who know what they're doing use. I have been running external bandpass filters on my radios for 27 years in multi/multi contests venues.

At 100w, sure, the Flex would probably handle it fine at Field Day. But so does the 7300. I was just at an outing in the park not but a month ago, with my 7300, which is my usual field radio. There were 9 or 10 HF radios out there at once, and the only thing that interfered (raised the noise floor about 1.5 S-Units) was a WWII era RTTY transmitter on 40m USB, while I was on 15m USB. As soon as I put the external bandpass filters on, that very minor interference disappeared immediately.

So I honestly don't know where all this interference and overload talk comes from, but that's okay.

 

[RocketNJ]

LoL. Yes, Yaesu radios prior to the FTdx 100D and FTdx10 are horrible with third order IMD.

The Icom 7300 isn't terrible but same band, depending on antenna spacing, you can see the TX phase noise on another receiver. The Flex 6600M with 7th order bandpass filters is very good @ 100 watts for Field Day. I will be getting the new Flex Tuner Genius in a couple of weeks and thinking of selling my mint 1 month old HF Auto and investing in a set of good bandpass filters for here at home. I am just getting into SO2R so like alcahuete, I want to do it right

 

[jazzboypro]

Correct...you know...like all the major contest stations and hams who know what they're doing use. I have been running external bandpass filters on my radios for 27 years in multi/multi contests venues.

At 100w, sure, the Flex would probably handle it fine at Field Day. But so does the 7300. I was just at an outing in the park not but a month ago, with my 7300, which is my usual field radio. There were 9 or 10 HF radios out there at once, and the only thing that interfered (raised the noise floor about 1.5 S-Units) was a WWII era RTTY transmitter on 40m USB, while I was on 15m USB. As soon as I put the external bandpass filters on, that very minor interference disappeared immediately.

So I honestly don't know where all this interference and overload talk comes from, but that's okay.

Out of curiosity can you tell us what filters you are using ? it looks very interesting.

73
va2fcs

 

[alcahuete]

LoL. Yes, Yaesu radios prior to the FTdx 100D and FTdx10 are horrible with third order IMD.

The Icom 7300 isn't terrible but same band, depending on antenna spacing, you can see the TX phase noise on another receiver. The Flex 6600M with 7th order bandpass filters is very good @ 100 watts for Field Day. I will be getting the new Flex Tuner Genius in a couple of weeks and thinking of selling my mint 1 month old HF Auto and investing in a set of good bandpass filters for here at home. I am just getting into SO2R so like alcahuete, I want to do it right

You can't go wrong with that setup. No two ways about that. That will make a great SO2R setup! Not to get off topic, but how do you like your HF Auto?

Out of curiosity can you tell us what filters you are using ? it looks very interesting.

73
va2fcs

I use the Low Band Systems bandpass filters. You can get them from DX Engineering. They are not cheap by any stretch of the imagination, but they work incredibly well. On their own, they provide around 60 dB of rejection (mine all measured better than that), and if you use them with a multiplexer, to use a tri-band beam with 3 radios, for example, you get anywhere from 80 to 120 dB of rejection.

 

[RocketNJ]

HF Auto with W1TR's software works very well to track the radio's VFO frequency. The tuner does not have CAT or CI-V in.
I am going to sell it within a couple of weeks when the Tuner Genius arrives. It is about 3 weeks old so will take a hit when I sell it but needed an auto tuner to carry me over for a month or so when I sold the KPA1500 and moved to the Power Genius amp.

Just did about 7 hrs in the contest and everything is working well.