VFO/ Sig Gen with HW-101


nz0tham@...
 

I have been thinking about trying to adapt my VFO/Sig Gen to use as a digital VFO with my Heathkit HW-101.  The HW-101 has a reverse tuning output of 5.5 to 5.0 mHz with 5.5 being the low end of each bands segment and 5.0 the top.  That looks to be easy to do with the QL VFO.  What I am looking to do is to use the QL VFO in place of the original analog VFO by feeding its output ( may need to be amplified) into the the rig mixer stages.  This can be accomplished easily by unplugging an RCA cable from the original VFO and plugging it into the QL VFO.  What I’m struggling with is how to display the actual frequency of each band on the QL readout instead of the 5.5 to 5.0 base frequency.  Reading through the manual I think I can use the iF offset to that but I’m not sure.  Or maybe it’s just not possible?  Any input greatly appreciated

73, Bill NZ0T


bojan.naglic
 

Hi Bill,

By choosing IF offset = -5.500 you get this:
display 0 kHz: output 5500 kHz
display 500 kHz: output 5000 kHz.

73 Bojan S53DZ


ajparent1/kb1gmx
 

It will need an amp as well.

Allison
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ajparent1/kb1gmx
 

I forgot...
With the D-VFO it may require a switch to "zero out" the frequency
error due to sideband selected and the heterodyne oscillators.

In some HW101s there is noticeable drift from the crystals in the
1st LO due to heating of the crystals.

Due to the heterodyne 1st LO crystals, the exact frequency for each
band will have error despite precise VFO.  You can try to net in the
crystals but their age and circuit used might not allow enough
tuning range for that.

Allison
-------------------------------
Please reply on list so we can share.
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nz0tham@...
 

Allison,

Thanks I do have a buffer/amp ready to go.  I had not thought about the LO crystal issue though, thanks for bringing that up.

73, Bill NZ0T


Justin Kelly
 

In the past I had considered using an Si-5351 variant to replace not only the VFO but the crystal oscillators too, the thinking was with a single reference being used everything would drift together. 

Justin 


Bill Collins
 

That sounds like a good idea. You could even GPS lock it

On 04/12/2022 4:39 PM freefuel@... wrote:


In the past I had considered using an Si-5351 variant to replace not only the VFO but the crystal oscillators too, the thinking was with a single reference being used everything would drift together.

Justin



Ronald Taylor
 

Bill, I have a VFO Sig Gen here and an HW-101. I built a little lowpass filter between the two and no amplifier. I’m getting over 2 volts sinusoids into the HW-101 in this configuration and it’s working well. Plenty of drive to get full transmit output too. So nothing fancy and no attempt at rig alignment yet. All I’ve done so far is to offset the IF offset a little bit from the -5,500 mark to compensate for the old crystal in use for the band I’m listening to. Crystal drift with temperature doesn’t seem to be as much an issue as simply how far off they are after a short warmup. And I’m sure it will be a little different for each band. Fun stuff though. 

Ron

On Tue, Apr 12, 2022 at 13:54 Bill Collins <photo@...> wrote:
That sounds like a good idea. You could even GPS lock it
> On 04/12/2022 4:39 PM freefuel@... wrote:
>

> In the past I had considered using an Si-5351 variant to replace not only the VFO but the crystal oscillators too, the thinking was with a single reference being used everything would drift together.
>
> Justin
>
>
>






nz0tham@...
 

Hi Ron,

Thanks for the info!  Are you set up so the correct frequency shows on the VFO readout and, if so, how did you set that up?

73, Bill NZ0T


Ronald Taylor
 

Yes, everything but the MHz part (just like on the dial) is displayed. I made it accurate or at least closer by adjusting the actual offset a little. 

Go to the IF offset menu. Click the encoder button to get the main menu then turn the encoder to get to IF Offset and then first set it to -005,500,000 and then go to the band of interest and tune in a known frequency. In my case it was 20 meters and the Maritime Mobile net on 14.300. Then note the difference between the readout and the known frequency and adjust the IF offset by that much. If you go the right direction it will be pretty close and if you go the wrong direction it will be twice as far off as it was before you adjusted it :-)
My final offset was -005,498,900. Your results are guaranteed to vary. 

Remember that it won’t be consistent when you change bands either because each of the Heterodyne crystals is off by its own amount. Also it won’t be correct if you change sidebands. The Hw-101 has an offset adjustment to compensate the internal VFO for that. 

Still fun though. 

73… Ron

On Tue, Apr 12, 2022 at 14:52 <nz0tham@...> wrote:
Hi Ron,

Thanks for the info!  Are you set up so the correct frequency shows on the VFO readout and, if so, how did you set that up?

73, Bill NZ0T


Rod Smith
 

That *does* sound fun and very satisfying.  

I wonder whether you’ve ever tried or considered trying a “huff ‘n’ puff” stabiliser on the original VFO?

73
Rod
G0VKX


nz0tham@...
 

I just happen to have a VFO/Sig Gen I built a few years ago so I thought it would be fun to try it with the HW-101.  I installed a 60M QL LPF in it yesterday and tried it with the HW-101 with no luck so far.  Either I have the wrong frequency set and/or I need to boost the output with a buffer amp I have here.

73, Bill NZ0T


Ronald Taylor
 

Bill, I built a homebrew version of the QL LPF and I had to remove 2 turns from each toroid to get it to pass the 5.0 - 5.5 MHz output of the VFO. I got over 2 volts pk-pk from mine and it works well with the HW-101. Hope that helps. 

Ron

On Sat, Apr 16, 2022 at 06:10 <nz0tham@...> wrote:
I just happen to have a VFO/Sig Gen I built a few years ago so I thought it would be fun to try it with the HW-101.  I installed a 60M QL LPF in it yesterday and tried it with the HW-101 with no luck so far.  Either I have the wrong frequency set and/or I need to boost the output with a buffer amp I have here.

73, Bill NZ0T


nz0tham@...
 

Hi Ron,

I tried it without the LPF with no difference.


Ronald Taylor
 

Do you have a scope to measure the voltage coming out of the VFO? Like I mentioned, I saw around 2 volts Pk-Pk at 50 ohms. The HW-101 is looking for a 50 ohm match (47 ohm resistor) at the interface point. And at least in my case the 2v signal seems to be plenty.

Ron 

On Sat, Apr 16, 2022 at 3:03 PM <nz0tham@...> wrote:
Hi Ron,

I tried it without the LPF with no difference.


nz0tham@...
 

Hi Ron,

All I have is a cheap little DOS Shell scope and it's showing about 2V Pk-Pk but no idea how accurate it is LOL.

Bill


Ronald Taylor
 

I think those DOS Shell scopes are only rated for audio work. I don’t know how you’re connecting the VFO to the HW-101. In my case, inside the radio I used a female-female RCA adaptor and an old audio cable to bring it out to plug in to the RCA Jack I had installed on the VFO. I noticed the radio’s RCA plug didn’t make firm contact with the adaptor I used and I had to squeeze the plug’s shell slightly to get good contact with the adaptor to get it working. 

Hope it’s something simple like that for you. I’m really enjoying operating the HW-101 with good stability. Tuning is fast on SSB because most hams stay on a 1 KHz resolution. I set tuning resolution to 1 KHz and just tune them right in. The exceptions are the ones that stay 500 Hz off, in which case I have to go to 100 Hz tuning. But there aren’t many of them. And of course tuning CW you need to be at 100 Hz resolution or lower. I have the CW filter in my rig and it was almost impossible to tune stations in with the internal VFO. Much easier with the QL VFO. 

Ron

On Sat, Apr 16, 2022 at 19:08 <nz0tham@...> wrote:
Hi Ron,

All I have is a cheap little DOS Shell scope and it's showing about 2V Pk-Pk but no idea how accurate it is LOL.

Bill


nz0tham@...
 

Hi Ron,

Sorry for being such a pain!  Would you mind giving me the exact settings you have in your VFO?  Maybe I'm not understanding how to configure it properly.  My cable and connectors check out fine BTW.

More simply -  please talk to me like I'm 5!

73, Bill NZ0T


Ronald Taylor
 

Not a pain Bill. I'll step you through the process I used. Hopefully it will get you there. 

1. click the encoder button once to get to the menu. Adjust the encoder to select "IF Offset". Click the left button to highlight the +/- symbol and use the encoder to select "-". Then click the left button as required to step to the next digit that needs changing and change it using the encoder. You want to change the IF Offset initially to "-005,500,000". When you get all the digits changed to what you want, use the left button to step one click past the last digit to the point where the display is there but no digits are underlined, and then click the encoder button. 

2. The displayed frequency will be something strange, probably, and will most likely have an error message "E" after the frequency. Adjust the encoder to get a display frequency all the way to down below 500 KHz (0,500,000). The error message will probably disappear after you get below 5.5 MHz. Your VFO will now display zero to 500 KHz as 0,000,000 to 0,500,000 just like the HW-101 VFO as you tune clockwise on the encoder. If you measure the VFO output signal it will be going backward from 5.5 MHz to 5.0 MHz as you tune clockwise on the encoder. 

3. The unit boots up on default to Preset Zero. I have my preset Zero set to "000,250,000  0 0" which brings it to 250 KHz, displayed as "0,250,000" . To set Preset Zero to a start frequency of your choice click the encoder button, then use the encoder to select menu item ""Preset 0". Then click the left button to get to each digit that needs changing. Change the digit by turning the encoder, then click the left button to advance to the next digit that needs changing. As above, click to one step past the last digit (1 Hz Digit) so that no digits are underlined, and click the encoder button to accept.

Note: it will tune above 500 KHz in this configuration but not below Zero KHz. Just as with the HW-101 VFO, the Band select MHz reading is added to the VFO KHz readings to get the final frequency on all bands. You probably still won't be exactly on the right frequency unless you do a complete rig alignment, and some of the old crystals may not come up on exactly the correct frequency even with alignment due to aging. I picked the band I will use most (20 meters) and adjusted the IF Offset slightly different from the -005,500,000 frequency to net the 20 meter band frequencies very closely. The great thing is that you will now be very stable in frequency compared to before and if netted, you can get most SSB users tuned in just tuning in 1 KHz steps. 

If you do all this and it still doesn't work, please make sure you are connecting the male RCA connector end of the short RG-174 coax coming from the circuit board, to your outboard VFO through whatever connector/adaptor arrangement needed to do so. This leaves the female RCA panel connector on the VFO housing open/unused. I have not heard any oscillator activity from the old VFO which I left running. 

Good luck Bill. If you are still having issues with it, please contact me with a private message and I'll share my phone number so we can discuss it a little quicker than we are at the moment. Best 73 ... Ron

On Sun, Apr 17, 2022 at 12:14 PM <nz0tham@...> wrote:
Hi Ron,

Sorry for being such a pain!  Would you mind giving me the exact settings you have in your VFO?  Maybe I'm not understanding how to configure it properly.  My cable and connectors check out fine BTW.

More simply -  please talk to me like I'm 5!

73, Bill NZ0T


Ronald Taylor
 

Bill, I misspoke on one item in the last note. Obviously, the HW-101 VFO dial tunes such that rotating the knob clockwise lowers the frequency  and CCW raises it, but the dial is labeled left to right as 0-500. Anyway, the displayed KHz digits on the QL VFO will be correct and CW rotation of the encoder will raise the frequency ... on all bands... 73 ...Ron


On Sun, Apr 17, 2022 at 2:57 PM Ronald Taylor via groups.io <wa7gil=gmail.com@groups.io> wrote:
Not a pain Bill. I'll step you through the process I used. Hopefully it will get you there. 

1. click the encoder button once to get to the menu. Adjust the encoder to select "IF Offset". Click the left button to highlight the +/- symbol and use the encoder to select "-". Then click the left button as required to step to the next digit that needs changing and change it using the encoder. You want to change the IF Offset initially to "-005,500,000". When you get all the digits changed to what you want, use the left button to step one click past the last digit to the point where the display is there but no digits are underlined, and then click the encoder button. 

2. The displayed frequency will be something strange, probably, and will most likely have an error message "E" after the frequency. Adjust the encoder to get a display frequency all the way to down below 500 KHz (0,500,000). The error message will probably disappear after you get below 5.5 MHz. Your VFO will now display zero to 500 KHz as 0,000,000 to 0,500,000 just like the HW-101 VFO as you tune clockwise on the encoder. If you measure the VFO output signal it will be going backward from 5.5 MHz to 5.0 MHz as you tune clockwise on the encoder. 

3. The unit boots up on default to Preset Zero. I have my preset Zero set to "000,250,000  0 0" which brings it to 250 KHz, displayed as "0,250,000" . To set Preset Zero to a start frequency of your choice click the encoder button, then use the encoder to select menu item ""Preset 0". Then click the left button to get to each digit that needs changing. Change the digit by turning the encoder, then click the left button to advance to the next digit that needs changing. As above, click to one step past the last digit (1 Hz Digit) so that no digits are underlined, and click the encoder button to accept.

Note: it will tune above 500 KHz in this configuration but not below Zero KHz. Just as with the HW-101 VFO, the Band select MHz reading is added to the VFO KHz readings to get the final frequency on all bands. You probably still won't be exactly on the right frequency unless you do a complete rig alignment, and some of the old crystals may not come up on exactly the correct frequency even with alignment due to aging. I picked the band I will use most (20 meters) and adjusted the IF Offset slightly different from the -005,500,000 frequency to net the 20 meter band frequencies very closely. The great thing is that you will now be very stable in frequency compared to before and if netted, you can get most SSB users tuned in just tuning in 1 KHz steps. 

If you do all this and it still doesn't work, please make sure you are connecting the male RCA connector end of the short RG-174 coax coming from the circuit board, to your outboard VFO through whatever connector/adaptor arrangement needed to do so. This leaves the female RCA panel connector on the VFO housing open/unused. I have not heard any oscillator activity from the old VFO which I left running. 

Good luck Bill. If you are still having issues with it, please contact me with a private message and I'll share my phone number so we can discuss it a little quicker than we are at the moment. Best 73 ... Ron

On Sun, Apr 17, 2022 at 12:14 PM <nz0tham@...> wrote:
Hi Ron,

Sorry for being such a pain!  Would you mind giving me the exact settings you have in your VFO?  Maybe I'm not understanding how to configure it properly.  My cable and connectors check out fine BTW.

More simply -  please talk to me like I'm 5!

73, Bill NZ0T