Hmmmm. What to do with this old HP 606B signal generator...

[N2CHX]

I just got rid of a bunch of stuff. My daughter hooked me up with this guy that buys old electronics and antiques. Made a bit of $$ cuz I'm trying to downsize my collection of semi-useless junk. One thing I couldn't even give him for free was an old HP 606B precision signal generator. I've had it kicking around for years and years now since I rescued it from a building that had a roof that was about to collapse. It's in almost perfect shape and works quite nicely, so I have found. I never fired it up until today.

I also noticed that not only will it do 30 kHz to 65 mHz, it is capable of 100% AM modulation and +20 dBm into 50 ohms. That's not bad. I'm thinking add a simple homebrew broadband amp and I've got myself a nice QRP transmitter for CW or AM. Probably will have to add a low-pass audio filter for AM also, but anyway...

Ideas?

[N8YX]

What's the stability like?

[N2CHX]

What's the stability like?

It's actually well-known for its stability. I have yet to give it a good long test on that, but I will. Seems to be good so far. There is also an optional PLL you can get for this thing that locks it down nicely, from what I've read. Wonder if I could find one cheeeeeaaaap.

[N8YX]

Sounds like a good candidate for an FM transmitter, and as an exciter for a high-level AM rig.

What kind of drive power have you measured out of the thing into 50 ohms? If 500mw-1w, you could build a decent solid state PA from a pair of MRF433s (or equivalent) driving a pair of 2SC2879s. That arrangement ought to net you 75w FM and 100w PEP on AM, assuming forced air cooling.

[N2CHX]

Sounds like a good candidate for an FM transmitter, and as an exciter for a high-level AM rig.

What kind of drive power have you measured out of the thing into 50 ohms? If 500mw-1w, you could build a decent solid state PA from a pair of MRF433s (or equivalent) driving a pair of 2SC2879s. That arrangement ought to net you 75w FM and 100w PEP on AM, assuming forced air cooling.

It's +20 dBm into 50 ohms, which is 100 mW.

[N8YX]

It's +20 dBm into 50 ohms, which is 100 mW.

Three-stage amp called for:

Drive a 2N4427 with the generator and then the brick with the '4427. Cubic put all of the circuitry on one board (per a Motorola RF Applications note) and you could copy that setup.

A couple of their designs placed bandpass filtering ahead of the predriver with a switched low-pass filter arrangement after the final amplifier pair.

Or drive a pair of 12BY7As in push-pull into a pair of 4X150As with 300-450v on the screens.

Whatever you have parts for...

[N2CHX]

Three-stage amp called for:

Drive a 2N4427 with the generator and then the brick with the '4427. Cubic put all of the circuitry on one board (per a Motorola RF Applications note) and you could copy that setup.

A couple of their designs placed bandpass filtering ahead of the predriver with a switched low-pass filter arrangement after the final amplifier pair.

Or drive a pair of 12BY7As in push-pull into a pair of 4X150As with 300-450v on the screens.

Whatever you have parts for...

Interesting ideas. I think I will definitely save this box for such a project when I can afford to put the parts and time into it. The thing would be capable of transmitting on all the bands, through the full band. I'd have to be careful to make sure I didn't accidentally go out of band, but I've had rigs where that was a possibility before and it's no big deal... and I love CW too. AM would be fun. If it's stable enough, a mod to do FM on 6 meters would be an interesting idea as well. It's a big, badass box. I will put it back in storage for now and count it among the things I will use for a future project.

[N8YX]

I started an "Island homebrew transceiver" thread a while back, wherein each participant could design a module of the rig and when they were all coupled together you would have a working rig.

As soon as I get a few projects out of the way this summer I'm going to revisit that idea - from back to front. First out of the gate will be an AF PA module which features sidetone, muting and VOX controls. An internal header will allow fitting of an AF DSP module such as a BHI or SGC unit. I/O levels and control signals will be documented for anyone wishing to design their own variant and this theme will be carried through the remainder of the project.

Right now I'm leaning towards building something similar an FT-726 or 736 in execution. That is, an IF which can accept several RF modules. These could be remote-controlled or local to the host chassis.

That signal generator of yours might come in handy for aligning such a construct if you choose to duplicate it.

[N2CHX]

I started an "Island homebrew transceiver" thread a while back, wherein each participant could design a module of the rig and when they were all coupled together you would have a working rig.

As soon as I get a few projects out of the way this summer I'm going to revisit that idea - from back to front. First out of the gate will be an AF PA module which features sidetone, muting and VOX controls. An internal header will allow fitting of an AF DSP module such as a BHI or SGC unit. I/O levels and control signals will be documented for anyone wishing to design their own variant and this theme will be carried through the remainder of the project.

Right now I'm leaning towards building something similar an FT-726 or 736 in execution. That is, an IF which can accept several RF modules. These could be remote-controlled or local to the host chassis.

That signal generator of yours might come in handy for aligning such a construct if you choose to duplicate it.

That'd be really cool. I would love to build a QRP rig for PSK. I actually have an idea for a psk rig that would run off a Raspberry Pi and would not require a balanced modulator, nor would it use inverters for phase modulation. It's just an idea that I want to see if it will work. In theory, it would.

[mw0uzo]

I started an "Island homebrew transceiver" thread a while back, wherein each participant could design a module of the rig and when they were all coupled together you would have a working rig.

As soon as I get a few projects out of the way this summer I'm going to revisit that idea - from back to front. First out of the gate will be an AF PA module which features sidetone, muting and VOX controls. An internal header will allow fitting of an AF DSP module such as a BHI or SGC unit. I/O levels and control signals will be documented for anyone wishing to design their own variant and this theme will be carried through the remainder of the project.


I could make a PIC controller for controlling several cheap ad9850 dds modules and a 2x20 or 4x20 character lcd. That would make a superhet radio that would work on any band in any mode, given the appropriate bpfs and lpfs. A few weeks ago I got the code to control the 9850 working on a breadboard.

[mw0uzo]

I've also just got a piece of test equipment. A HP8922B gsm test set and spectrum analyser. Analyser works from 5Mhz to 1Ghz. Its also an RF gen from 10Mhz to 1Ghz.