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Author Topic: "New" HW-8  (Read 5123 times)
KE7WAV
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Posts: 126




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« on: February 26, 2010, 09:16:35 PM »

So I just purchased and HW-8 and it should be here anyday now.

I was wondering what advice, info, etc. that those of you who have worked with them before might have for me. What obstacles should I know about? Or what ideas do you have that will help me with my new rig?

The HW-8 has an S-meter installed and a SO-239 jack in the back but those are the only mods the last owner knew of.

I downloaded and read the manual but real life experience and elmers always seems to help me a little better.

TNX es 73
KE7WAV
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WX7G
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Posts: 5975




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« Reply #1 on: February 27, 2010, 10:11:49 AM »

Being a direct conversion receiver it will receive a station on two spots on the dial. Make sure you have the station tuned on the upper spot and you will be on the correct frequency. It's a nice little rig.
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KE7WAV
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Posts: 126




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« Reply #2 on: March 01, 2010, 11:37:31 AM »

I've got it and I used it but the meter appears to be off a bit.  So I need to get a few tools to aligned it but it is worlds better than my old HW-7.
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WB6BYU
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Posts: 13147




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« Reply #3 on: March 01, 2010, 01:20:52 PM »

Quote from: KE7WAV
... the meter appears to be off a bit...

In what way?  Originally the meter was simply a relative output indicator, it isn't
calibrated at all.  (And, if it were, the scale wouldn't be linear in watts.)  You just
use it to adjust the loading control for maximum, that's it.  It measures RF voltage,
not power, so with a high impedance load (like a full wave loop) it will read higher,
and a lower impedance load (like the same loop fed through a quarter wave of
coax) it will read lower for the same output power.  Don't expect anything more
from it than that (unless you change out the power detector circuit.)  It isn't any
good for adjusting a tuner without modification, either.  (I added a power meter
to mine so the meter reads the difference between forward and reflected power.
Sort of...  It isn't perfect, but that way I can just tune everything for maximum
output, even if I don't know exactly what that is.)

The S-meter mod was basically to connect it to the receive audio in the same
manner - it just measures the audio voltage (on the top of the volume control
if the mod was done correctly.)  This gives you a relative indication of stronger
or weaker signals (depending somewhat on the tuning) but again isn't a precision
instrument.  I just estimate signal strength by ear by how far I have to turn down
the RF gain control.
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KE2EE
Member

Posts: 21




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« Reply #4 on: March 01, 2010, 04:44:23 PM »

I built a new HW-8 from Heathkit in 1979 as a Novice, a great little rig at the time. Some tips: you may notice the dial calibration off some. Adjust the trimmer screw on the main variable VFO cap at 7.00 mhz and adjust L9 (inside the large square coil cover)at 7.250 mhz on TX with dummy load. There is a blue pot near the T/R relay to adjust the keying delay. The other blue pot on the board adjusts sidetone level. I had no issues with my rig which would put out about 1.5 watts. I still have the radio and would like to get back into QRP this spring at the picnic table while camping.  
Any other detailed questions, my e-mail is good at QRZ.

Mike
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VE3WMB
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Posts: 286




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« Reply #5 on: March 02, 2010, 05:42:28 AM »

If you can manage to find a copy of "The HW-8 Handbook" by Mike Bryce, WB8VGE it is well worth it. This is a compilation of mods and fixes to common issues with the HW-7/HW-8 and HW-9 series of rigs.
I am not sure if it is still in print so I would suggest you drop Mike an email and see if he still has any copies or knows where you might get one.

For instance, my HW-8 was off the air for a number of years and when I went to use it I discovered an issue with "motorboating" on some of the higher bands. A quick look at the HW-8 Handbook indicated that this was a common problem with a simple solution of lifting the end of one choke and inserting a resistor in series with it .. this ended up doing the trick.

My HW turned 30 last year !

Michael VE3WMB
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KE7WAV
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Posts: 126




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« Reply #6 on: March 03, 2010, 11:44:47 AM »

I am sorry I meant to say my tuning dial.  I just need to align the rig but I don't have an RF etc at the moment but those are easy to homebrew.  I just had a QSO with a buddy and our freq was 7.120 bu tthe radio was showing 7.115, So I want to fix it!  Thank you all for the input.
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WB6BYU
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Posts: 13147




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« Reply #7 on: March 03, 2010, 02:50:31 PM »

And if you pack your spare socks inside the case to save room in your backpack, it
shifts the frequency by about 40 kHz.  Guess how I know that...
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VE3WMB
Member

Posts: 286




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« Reply #8 on: March 04, 2010, 06:33:59 AM »

You may find that it is hard to get an accurate reading off of the tuning dial of the HW-8 even after it is re-calibrated. In my experience having accuracy to 5Khz is doing pretty well.

I discovered that the tuning cap in my HW-8 is rather non-linear,
in fact when tuning up the band the frequency actually goes down at one point!  

If you don't mind making mods you might consider adding a Small Wonder Labs Freq-mite (www.smallwonderlabs.com) which will give you a readout of your frequency in Morse Code. Physically this would
only require only one small hole to add a momentary push-button switch.

W8RIF has documented this mod to his HW-8 at :
http://home.frognet.net/~mcfadden/wd8rif/hw8-freqmite.htm

Cheers,

Michael VE3WMB
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KE7WAV
Member

Posts: 126




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« Reply #9 on: March 04, 2010, 07:39:17 PM »

VE3WMB  Thanks for that link and info I think I may do that.  That was a great link and some good info!
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KE7WAV
Member

Posts: 126




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« Reply #10 on: March 04, 2010, 07:42:43 PM »

SOCKS IN THE CASE?Huh  Wow, I can only imagine.  That is great.  I will try to avoid that one next field day. hihi
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W8AAZ
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Posts: 335




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« Reply #11 on: March 17, 2010, 04:05:47 PM »

Like all things do not try to make too much out of it. You could modify it till forever if  you had the time and money.  But then it would not be an HW-8 and would have about zero resale value to a stranger. Best just maybe try some of the minor mods that are well known and agreed upon and do not change the appearance, just clear up some deficiencies, and before that try to get it tuned up to working correctly to begin with.  There are too many modern QRP rigs that can outrun it and that is where you should focus if you are thinking of throwing alot of money at it, to make it a silk purse from a sows ear. If it don't cut it, keep it as a backup or just for fun, like the old classic rigs are.
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W8AAZ
Member

Posts: 335




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« Reply #12 on: March 17, 2010, 04:09:53 PM »

As for dial calibration, you might be able to use a digital tuning HF rig in a jam to adjust it, like with the power turned to minimum into a dummy load on the dig. tuned rig, and a dummy antenna on the HW to bring signals down within reasonable non overload levels. Usually you do not adjust the slug and cap at the very ends of the tuning range, but at some point inside the range, at either end within the extremes. I had one and got it to tune within a couple KHZ as I recall, by back and forth and noting the errors each time till on average the errors were minimal. Especially in the QRP part of the band. Keeping in mind which side of the carrier freq is the correct one to tune to.
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AJ4MJ
Member

Posts: 48




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« Reply #13 on: March 26, 2010, 10:22:36 AM »

You can also build a crystal calibrator.  There was plans for one a few months back in QST.  Basically it's a 1mhz TTL can oscillator that you use counters to divide down to 25Khz.  Because of the nature of square waves, it will emit a harmonic every 25khz, so you can use these "known" positions to calibrate your dial.  

Some "deluxe" calibrators offer multiple divide-down outputs.  If you suspect that your dial is more than 25khz off, you could switch to a 100khz mode to eliminate that uncertainty.

I don't worry about frequency too much.  My Norcal 40A just has sharpie marks every 10Khz.  I have pre-tuned the radio to stay within the band edges (it only has 43Khz of range).  I just zero-beat to the other guy and log the QSO as my best guess or as "40M".

Welcome to QRP!

72 de AJ4MJ
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GW0NVNN1XIH
Member

Posts: 1




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« Reply #14 on: April 06, 2010, 02:53:16 PM »

I have done some of the mods from the HW-8 handbook First Edition 1994 and from the Second Edition 2003.  Also those that apeared in the GQRP handbook many years ago.

  The HW-8 has a classic look and works.  I use one with headphones or a speaker in my home office as a ham receiver.  
There are some mods which can help with performance and ease of use.  Without making aditional holes to the case.  These are:-

Stablise the vfo and hetrodyne crystal oscilators. Details in HW-8 Handbook
Change the frontend device eg 2N4416.
Use a heatsink on the PA device.
Change the PA device for either a 2SC2166 or 2SC5739.  This will increase the rf output depending on supply voltage.  I was able to obtain 3W-6W from 15m-80m
An internal battery pack.  They can be charged using extra pins in the 6 pin Molex power socket.

If you don't mind drilling holes:-
Wire antenna terminals.
2.1mm power connector.
3.5mm headphone socket.
switched white bright led for dial display.
Change the selectivity control for a 3pole 4way switch.  So you can build a batery meter,rf power meter, refected power meter,an audio wide and narrow filter all controlled from the same switch.
A switched 50 Ohm load.

Some to be done:-

Change the biasing around the MC1496 as described in the old ARRL Solid State Design Handbook.  This is to improve the dynamic range of the product detector.  Change the use from unbalanced inputs and outputs to balanced.

As has been mentioned if you want a better performing qrp rig there are many better out there to construct for the price.  There are only so many modifications you can do before you have to totally redesign the transceiver.  I use an FT817 on my travels. But as always.  If you can hear the stations stongly, have good propagation, a correctly working antenna and operating technique you will be able to work the stations.  Even with the HW-8.
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