Filter Modification for Harris RF-590

[KE1GF]

Hey crew, I've been working on my RF-590 RX. I added on an aftermarket filter to it.



here's the lineup

AM: 3.2KC, 6.0KC, 9KC, 16KC
FM: 9KC, 16KC
USB: 3.2KC
LSB: 3.2kC
ISB: 3.2K (using the USB and LSB filters)
CW: 0.3KC, 1KC



There's a bit more to do than soldering in the filter and I haven't done a writeup yet.

I'll be working on one soon, the complicated thing is that Harris customizes the firmware. So I really can't be sure that the information I provide will be of any use.

-Bill 'GF

[WA1GFZ]

Very Cool Bill,
Where did you get the small filter? Racal uses the same blue filters.
I wonder if you have access to a couple good generators and a combiner.
A RMS volt meter would be the monitor. Also a generator is used to measure the the phase noise/ crud rejection. I will send you a copy of my EXCEL receiver score card
that I have for a number of premium receivers. It would be nice to have the data for the RF590. It is another great design. I am working on an SDR interface for a 455 KHz. IF which you may like to play with. I have a friend doing the drafting now and hope he wants to produce some boards.
Someone sent me a little data on the RF590 and the close in phase noise looked very good.  fc

[KE1GF]

Initally Bob Sherwood posted on his website that he had 10KC Mechs like what you see in the rig... When I called he was out of them, but he offered me a 9KC 15 pole (crystal or ceramic)? Instead.

I am really impressed with the filter, I tune about 4.5-5KC either side of a station and their carrier drops right off. I was skeptical about it's performance but Bob assured me that I wouldn't be disapointed. I'm not sure about other aspects of the filter's performance.

The impedence of the 9KC is a bit lower than the collins mechs so I had to play a bit with some resistors, not bad just had to poke around with the scope and get the levels correct.

The real pain was going through the 32 filter combinations, I documented though. That code from Prem-RX wasn't accurate.

-Bill 'GF

[Glenn NY4NC]

Awesome receiver Bill!!!... I've long lusted after one, never had the money when they were available. I see them going for around 2k these days... would love to add one to my collection. Did you get it on E-bay? or from one of the surplus houses like Murphy's, Toronto, etc..

Is that the receiver you're using with your class-E station?

[WA1GFZ]

Bill,
I put a Sherwood 8 khz filter in the 6830 my drafting friend has. I was also impressed with the performance of that little filter. The price was a bit high. It would be cool to find his supplier. I'm about to build a wide band hot rod rx to go with the the tight one. I want to stack two filter modules in the module slot like the other unit but forced to use mechanical filters that are shorter. I want a 16 KHz selection.

I don't know if you can use crystal filters in that radio. I think the 590A allowed crystal filters. Harris used the same crystal filters as Racal and there are a lot around
from the RA6790s. I don't see the holes for crystal filters in your board. Racal used a resistive divider ahead of the 16 kHz filter to drop the noise down a bit.

If your radio has a 455 Khz output you could do SDR. fc

[KE1GF]

Frank,
         I believe that the 16KC filter is in one of the IF modules, it is not on the A4 IF filter module. The radio has two options 16KC or 20KC for wide-band operation.

Yes, the 590A comes with some crystal filters by default, I believe that they are for SSB but I'm not sure about all the details.

Yes, the rig has 455 filtered and unfiltered outputs, I've used my NE602 based down converter and fed approx 11KC bandpass signal into my sound card and used some nice spectum analyzer software.

-Bill 'GF

[KE1GF]

Awesome receiver Bill!!!... I've long lusted after one, never had the money when they were available. I see them going for around 2k these days... would love to add one to my collection. Did you get it on E-bay? or from one of the surplus houses like Murphy's, Toronto, etc..

Is that the receiver you're using with your class-E station?

Glenn,
         Yes I have two RX's that I use for AM an R-390A (I have an external synch detector on it) and the Harris.
I purchased it from T S&S, cream of the crop condition, new VFDs, fully calibrated, baked in and it came with a warranty.

I selected the original preselector which is discontinued. But if it gives out, there is a new Harris filter which drops right in. I spoke quite extensively with the tech at T S&S and the said  performance is negligible between the two.
 
Of course I waited until the warranty expired before I performed surgery. luckily I ordered my (590) right before the price skyrocketed and they ran out of inventory. The people at T S&S are great!

-Bill 'GF

[WA1GFZ]

Bill,
Go to sdradio.org and download ver.99 sdr software. It will decode I/Q or single I input. Beware it is addictive and yes there is a spectrum display. I have a few other software packages if you need links. Just put the 11 KHz offset into ver.99 so CF is at zero on the display. It has 2 am modes one a sync detector. The SDR interface I'm working on will mate to your radio. All you would need to do is select the input attenuator for the correct level.
I blew a chance for a 2368 a while ago and still kicking myself.

[KE1GF]

Bill,
Go to sdradio.org and download ver.99 sdr software. It will decode I/Q or single I input. Beware it is addictive and yes there is a spectrum display. I have a few other software packages if you need links. Just put the 11 KHz offset into ver.99 so CF is at zero on the display. It has 2 am modes one a sync detector. The SDR interface I'm working on will mate to your radio. All you would need to do is select the input attenuator for the correct level.
I blew a chance for a 2368 a while ago and still kicking myself.

Frank
       Sounds neat, I'll have to read up and tinker when I get the chance. I dont want to leave you with the impression that I am not interested, I've just got a full plate right now

-Bill
 

[WA1GFZ]

Bill,
We should do final schematic review in a day or so then my drafting buddy will make the boards. Looks like about $20 for parts and about $20 to $30 for pc board cost.
I don't know what we will do when we  are done but we may make some express pcb cards. fc

[KE1GF]

Bill,
We should do final schematic review in a day or so then my drafting buddy will make the boards. Looks like about $20 for parts and about $20 to $30 for pc board cost.
I don't know what we will do when we  are done but we may make some express pcb cards. fc

Okay sounds good dude, give me the go ahead whenever and I'll put a check in the mail, with some green backs for you to ship it.

I'm going to try to finish my tuner tomorrow and see if I an antenna up for 160M this weekend. It'll be a ratty sounding ricebox with about 125 carrier... The parts are comming in for the new rig, but I still need to plant my duff in the chair and make some mods to the artwork.

Oh BTW did you notice that QIX has seen the light and designed a totem-pole driven E rig?

-Bill 'GF

[Fred k2dx]

I would like to see the RF 590 filter modification, could it be posted in the mod section? My RF 590 is my favorite receiver. I sometimes run the IF output to a Sherwood SE 3 mk II synchronous detector, that works nicely.
I would particularly like to see how the 9 kc filter was added.

[WA1GFZ]

Hi Bill,
Steve and I have had a few emails and I'm waiting to see what he did. His pictures only show the final and 2 coax cables coming it. I've had 1 inductor in the 160 meter rig for 10 years now.  I also notice his two phases are getting closer to each other.

I will be interested in the performance of the parts he is using. They sound better than the drivers I'm using now. The performance and price are changing all the time.

So tell us how does the Harris compare to your other rigs. It is a very nice receiver.
fc

 

 

[KE1GF]

Hi Bill,
Steve and I have had a few emails and I'm waiting to see what he did. His pictures only show the final and 2 coax cables coming it. I've had 1 inductor in the 160 meter rig for 10 years now.  I also notice his two phases are getting closer to each other.

I will be interested in the performance of the parts he is using. They sound better than the drivers I'm using now. The performance and price are changing all the time.

I personally from my own experimentation and experience believe that there are a few problems that I saw. Yes the IXYS drivers are very impressive. I ordered up a couple dosen similar drivers to experiment with, they have a higher ron/roff but they are very similar for about all other aspects.

Running with 50% DC instead of a sine wave should get a much better yeild out of the transistors. The only problem is that it becomes difficult running that many drains in parallel because the RF impedance becomes very low. Which can be dealt with as you know, but it makes things more complicated.

So tell us how does the Harris compare to your other rigs. It is a very nice receiver.
fc

I don't have words in my vocabulary to describe how pleased I am. Call me crazy or whatever. I get a sense of good karma when I operate it. Possibly you have similar feelings of passion about the things you enjoy. Some people will go their entire life never understanding this.

But all in all, it's just another rig. I don't or try not to let my material possessions define who I am.

-Bill 'GF

[w3jn]

The RF-590 is one of my favorite receivers ever.  Used one professionally, but haven't owned one (yet).

73 John

[WA1GFZ]

I think the RF590 is one of the best analog designs out there. I like the Racal AM demodulator  better though. Both designs use dual crystal filters in the first IF but I like the Harris IF set up a bit better. The first mixer goes to Racal though. I think the best analog set up is a combination of 590, 6830 and Cubic R3030 each design has its strong and weak points.  I've never driven the 590 and would love to put it on a torture rack and see what it will do.

[KE1GF]

Frank,
         I have to admit that you were totally right about people's rice boxes picking up phantom splatter and other garbage. A few hams were in a QSO and P&M'ing the other day about heavy splatter from another station. I couldn't figure out what they were talking about at all. I have to say though it wasn't really a scientific observation, but I was dumbfounded to say the least... 

[w3jn]

DDS synthesizers are the devil's creation 

[KE1GF]

DDS synthesizers are the devil's creation 

I'm starting to believe it!

Hey so what if it took Harris 6 dual modulus PLL's to get 1Hz resolution across 30MHz

[WA1GFZ]

Glad to know I'm not nuts. I have heard guys driving FT1000s complain about crud that wasn't there.
Bill, The synthesizer in the 590A is like the 6830 Fractional n. The multiloop done correctly is a good machine. The WJ8718 is an old one but quite clean. The R3030 cubic is fair but close in about 10 dB more phase noise than the 6830.

DDS is a crap generator. It is only useful applied correctly as part of a pll. even analog devices new top of the line part running 1 GHz is a crap generator. It micht be usable with 4 or 5 flip flops hanging off the output.
I have a frequency generation method I would like to try with a good FPGA designer.
A variable TTL clock.  One of those things that keep me awake at night cooking fat off brain cells.