The AM Forum

I am looking for someone who can do as the title to this message states and that is repair and align a HA-5 VFO.  The unit seems to be in very good condition inside and out but the fact remains it does not work.  I started to look into it using the manual and even went so far as to construct the load for aligning the unit and even with that I was unable to find any hint of a signal coming from the unit so I have know way of knowing whether the unit is not oscillating due to a bad tube or whether it is so far out of alignment to to oscillate.   I even tried wrapping a wire multiple times around the oscillator and using a frequency counter looking for a signal and still no joy.  So that is about as far as my skill set will allow me to progress.  If you one have the desire to help to a fellow ham, and have the time to do the work please contact me about undertaking what I am sure is not a great big job for a person with a tube background.

Tnx and 73
Kevin - KG0MN
kg0mn at arrl.org

 O.k Ill try to help my fellow ham and hope that some of the other guys will to. :)
Is the vfo compleatly dead?
Do the tubes light?
 Iam not shure but I think this vfo runs of the transmitter power supply.. youll need a vom and do you have a scope? quik thing to check the key jack on the vfo..if its open it cuts off the oscillator off!!!

Is the transmitter working?

No the HA- 5 has its own power supply.for starters make sure the switch on front is in the Cal position, not off.

dale/ka5who

The HA-5 is self powered with its own transformer and as you suggested I checked to insure that all tubes are working they are and I even happened to have a new 0A2 and the Oscillator tube as well and even when replacing them it made no difference.  Using the original manual I checked the voltages at all of the places on the schematic that a voltage point and using my trusty Heathkit VTVM the voltages are all with 5 to 7 percent of what they should be.  The keying circuit specifies 36 volt I think and it checked out at 41 volts.  The alignment procedure say to use a capacitor/resistor load in the 80-10 meter output jack so I made one up and tried to see if varying the core of would perhaps bring it back into oscillation but still no joy.  Here is the link to the manual http://bama.edebris.com/download/hallicra/ha5/ha5.djvu

One thing on the schematic confused me, it says to put the band selector in the 80 meter position, tuning indicator at 3700, calibrator off and the switch off and key down.   I am not sure which switch they want in the off position because if it is it can not be the band switch and it can't be the calibrator switch either.  A bit of a error perhaps.  The OA2 has the nice  gaseous blue color to it and I notice on key down it changes colors.  I do have a scope that I just recently purchased, it is a 100MHz but I was a bit apprehensive about when to attach the probe and also was not certain what I should look for.  Thanks for the help.  Oh and before I forget yes the transmitter is working.

Kevin

One thing on the schematic confused me, it says to put the band selector in the 80 meter position, tuning indicator at 3700, calibrator off and the switch off and key down.

It means just what it says.The cal,off switch should be in the off posistion.I  have  the same vfo. Connect a 2 or 3 ft piece of cable to the 75 meter out put on the back,put switch in cal position ,turn receiver on in cw or ssb mode and look for tone.I just tried mine like that the receiver is abt 6 or 8 ft away and it worked fine,how ever my portable  freq counter would not find it.you must have the cable in the back.you can even hold on to the end with your hand to strengthen the signal.

dale/ka5who

Dale - first off thanks for offering some vital information and suggestions.  I did as you instructed and came up as quite as a church mouse.  So am I to surmise that the oscillator is not working? 

well it could be the VFO or the Crystal Oscillator or the mixer or the amp.
Could be in the Band Switch. With the proper probe on that scope, you could probably track it down. It will certainly let you see the waveforms at each stage of the circuit. Was it working prier? or is it a new acquisition?

I picked it up off ebay and the fellow said and I quote "when I put it on the shelf a number of years back, I can't recall but I think it was working."


Scott - I know this is lot to ask but could you tell me where in the circuit I would need to hook the scope probe to to see if each of the sections are working?


Thanks
Kevin

I finally got out the nerve and hooked the scope up to the 80 meter crystal and it give a reading of 9.000 MHz on the scope if you tune to the 40,20 and 115 meter band on the VFO the frequency changes to 12.500 MHz.  So it must be an indication that the crystal are good for me to get a reading of the actual frequency.  Not certain what the next step is.

  Looks like you ought to see a 5.0 to 5.5 Mhz
signal from VFO in there as well.

/Dan

that is what I thought to Dam since I can not find hide nor hair of a 5.00 MHz signal does that mean the oscillator is not working?

sure
the output of the xtal osc (sounds like that’s working) is on pin 7 of the 6BA7 mixer
the VFO output (5.0-5.5 Mc) is on pin 2 of the 6BA7 (V2) (also pin 6 of V1, the 6U8 VFO)
the output of the mixer is switched through wafers A, B, and C of the band switch
to one of three double tuned transformers depending on the band, and should be seen
on pin 1 of the 6AQ5 amp (V3)
(be careful, there is 230 VDC on the band switch)

Hope this helps

I might add also that I would expect the VFO and the XTAL Osc to operate all the time
only the Mixer and the Amp are keyed on by the keying circuit

From what I can see there is nothing going on with pin 2 of V2 the 6BA7 or on pin 6 of V1.  My eyes are crossing from looking at this thing all day and so I am going to call it a night.  So I think I will sleep on it decide my next move.  Thanks to everyone that has offered advice it is what makes appreciate this hobby.  If nothing else I can do what everyone else does, list it on ebay and claim that I have no way of testing it so I am not sure if it works or not.  LOL

Kevin,
     Nice looking old vfo. It would go well with my HT-40. Let me know if you list it.

     Seriously, though, I wonder if there isn't a missing jumper wire, or some keying aspect that is being overlooked. My Heathkit HG-10 oscillator stage is keyed along with the transmitter and keying it is done through the bias voltage from my HW-16. I suspect the DX-60 was similar.
     I sure wouldn't give up on the project as you can learn a whole bunch about these things by hanging in there. Do you have a friend in the area or at your local club that still is interested in old boat anchors? Another seasoned pair of eyes would be helpful. There might even be a Hallicrafters e-mail reflector or website like AMfone where people REALLY familiar with your vfo could help. I'm in a HW-16 and Heathkit list that I check every day. Good luck.
     All the best.  73s,   Marty, KK4RF

I thought about it last night and I think I will check the tube pins that Scott told me to check once again, and then I think I will heat up the soldering iron and re-heat some of the joints that don't look very good. 

Marty did you see the HA-5 that is on ebay now?  http://www.ebay.com/itm/Hallicrafters-HA-5-Heterodyne-VFO-/200866269198?pt=US_Ham_Radio_Transmitters&hash=item2ec490080e  There are two bids and the second bid went from I think in the 80.00 dollar range up to 200.00.  Someone wants this thing bad.

I would even pull the 6BA7 out of the circuit and check the vfo output again
just to eliminate the possibility that the mixer tube is the problem
also make sure the plates of the tuning capacitor are not bent and shorting anywhere
confirm that there is 130 volts on pin 3 of the 6U8
and maybe somehow confirm the 6U8 is OK
A nice tube tester would be handy

checking the connections and touching up the solder joints is a real good idea
now the coil L1 could be way out of adjustment, the 500 pf  cap C6 limits the
BW of the VFO to 500 Mc and the vfo output will drop off rapidly above and below its
designed pass band, and the limits set by L1 and C2, so some tweaking might bring it around

Wow! I want one of these VFOs.  :D

THANKS PETE
WOW I want one too  !!!!

should of typed Kc not Mc sorry my bad !!! ROFLRH

Kevin,
     That VFO, I think, is a very good one and I've watched many of them get bid-up big time on E-Bay. I've submitted reasonable bids in the past and have been shot down. But that's OK, I watch out for bargains. I go to hamfests just to see if I can find some reasonable prices on boat anchor gear.
     I have a can of De-OxIt spray that I spray on the contacts of all the switches with visible contacts and make sure I work it in really well, just in case you've got some crud/corrosion on the contacts. I even sprayed De-OxIt into the tube socket pins and work the tube in and out of the sockets numerous times for the same reason. Perhaps that will help.
     I hope you get it working, Kevin, as you already have the entire set-up for a great vintage station. The HT-40, with controlled-carrier modulation, works great on 75 meter AM fone when I run it through my old Heathkit SB-201. I check into the Old Military Radio Net Saturday mornings early with it. Interestingly, my Dad had a SX-140 receiver which I used as my Novice receiver in the late 60s. It worked well for me on 40.
     73s,  Marty, KK4RF
     

I wish my father-in-law KG0EQ SK was still alive he would have this thing figured out in no time.  Besides his degree as an Electrical Engineer he also was one of the main designers and trouble shooters for Hallicrafters for a number of year.  I have been very lucky to have been given all of his Hallicrafters information and bookets as well as a very large collection of manuals for ham gear, so military and others that he worked on.  He made my wife a stereo console out of a prototype AM/FM radio that Hallicrafters never came to market with and the funny part is it still works perfectly and sound as good as my Bose radio does..  That radio is close to 55 years now.  It is hard to beat tubes for a completely and far pleasanter listening experience.

I pulled the tube as was suggested and it made no difference at all.  I have notice one thing that seems odd, using the test load that the manual has you make, if I use that and hook the scope probe to it all I get is a 60Hz signal. On pin 1 of the 6AQ5 amp (V3) I still have the 9.00MHz signal.  I am going to try and find someone on one of the local nets that knows his way around this type of tubed VFO and see if they can help me out.

What are the voltage readings on pins 3 and 6 of V1? 

Set an external receiver to SSB mode, tuned to 5.25 Mhz, with an antenna lead near V1.  Tune the HA-5 back and forth near the center of its range.  If the variable oscillator portion is operational you should hear it in the test receiver.

This is a nice VFO and certainly worth repairing.  I have one and it is far more stable than the typical external "crystal replacement" VFOs.

If you are seeing a pronounced 60 Hz signal on the output
you may want to replace the electrolytic capacitors in the power supply

if seen on the output it would be coming from the 235 VDC source and would be riding
on the regulated voltage as well

Being a rank novice at this and not having a full arsenal of test the best piece I have would be the Digital Hitachi scope I got off Ebay that did not work when I got it and just reattach a wire to the power plug and it has worked perfectly since.  I was assuming that since it was coming up between 60 hertz and 59.9 that it had to be a leaky cap.  I will see if I can find someone to check the tubes out this weekend and make certain they are working and go from there.

FB Kevin
let us know how you make out
That is a nice VFO & would like to see you get it working

Hi Brian,
I was looking at the specs.on this vfo its kind of cool; as we all can see there are two oscillators. A mixer & power amp.

I can walk you through this trouble shoot if you like.
Here some basic checks.
Test the tubes,
Check tube Voltages,
Clean the band switches,I use rubbing alcohol,
The signal pass`s through these switches. Ill bet there dirty also try moveing the knob when checking for output..

Also this thing is cathode keyed: Do a cold ohm check from the cathodes of mixer & amp.
if there is an open the vfo will NOT have an output!

I just repaired a globe 775 and one of the band switch wafers was bad.
Get back and lets get this vfo working.

73   Steve

Thanks to Keith - K0GNW the VFO is back in operating condition.  What we found out or I should say, what he found out is that there are two different schematics for Hallicrafters HA-5. Looking at the cathode of V1A - 1/2 6U8A on my schematic it has a R2 - 120 ohms resistor and C8 a .005 capacitor that comes off of the cathode of the tube on pin 7.  The schematic that Keith found has pin 7 of that tube going directly to ground.  By doing removing those components the oscillator came to life and he was able to align it exactly as it stated in the manual.

I know Keith reads this forum and I want to take this opportunity to thank him for being so patient when it came to me asking questions and learning more about how it operates.  Now I am left to get a microphone see how it sound on AM as well as CW.  I also want to thank every on the forum for the advice they gave me and the genuine way you made me feel at home.

Thanks to everyone and happy 2013 and may you find a prize boat anchor of your own liking.

Kevin Elliott - KG0MN

Good catch
thanks for that info
you know didn’t even think of it before
but there was an errata sheet that accompanied the original
manual that stated that after the instruction manual was printed
but prior to production certain minor electrical changes were made
in fact item #1 on that errata sheet deletes R2 and C8
nobody put two and two together and knew you had access to
original schematics   :)
Very glad to hear you got it working hope to hear you on the air someday 73

I thought I would come back and let you know that the HA-5 VFO was fixed and then combined with the HT-40 and SX-140 Receiver I was able to get WAS with the old gear a number of DX stations as well.  I also found another HA-5 VFO that is real nice shape but when I got it it has AC hum that over-riding everything, so I got a new 3-stage capacitor from Hayseed Hamfest and then fixed that issue and the cap is the same size as the original.  Was at hamfest in California a while back and picked up an HT-40K transmitter and since the transmitter and VFO are is such good shape I think I may pickup a Drake 2B or C for the listening portion.  I have even done a bit of AM on the HT-40 and got decent reports so this project is finished and I may sell this setup of Ebay to finance the next restoration project now that I have learned a few things.

Thanks again to all those that helped me initially.

Kevin -KGØMN