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THE AM BULLETIN BOARD => Technical Forum => Topic started by: ke7trp on April 01, 2010, 10:51:33 PM



Title: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 01, 2010, 10:51:33 PM
I picked up an EF Johnson 2 meter VFO.  ITs small. Only 2 meter.  Has Xtal cable with plug for front of transmitter.  Then we have two wires, white with Red stripe and one white with black stripe. 

Anyone have the manual or information on this unit?   I am going to hook it to the Globe 2 meter am rig and I dont know what voltages its expecting..

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 02, 2010, 07:33:43 AM
Clark,

Are you sure it doesn't also cover 6 meters?  The only Johnson VHF VFO with which I am familiar is the little one that matches the 6N2 transmitter.  I have one of these and I believe I also have the manual if this is the same VFO that you have found.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 02, 2010, 12:14:23 PM
We need a picture and/or model #.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 02, 2010, 01:04:43 PM
Its very rare.  It is very small. Only covers 2 meters.  Someone told me that it was for the mobile they made. 

I have traced the wires down. 

white with red stripe. Goes to big resistor and oa2.  This must be Plate voltage.   My Globe outputs 360. 

White,  Goes to Tube filiments and pilot bulb.  Globe outputs 6.3 AC. 

White with Black stripe,   Goes to Cathode of 6bh6.  Must be a keying line?  Should this be grounded during operation?

Shield.. This goes to the globe case ground pin.

I think I better figure out a resistor for that HV.  The Johnson 6 and 2 mobile VFO says 250 to 300 volts. I have a solid 360 under key. Any ideas as to what or how to lower this?

Sorry for the crappy pictures. I have the thing all apart tracing wires down.  I am wiring the octal socket so this thing plugs in the Globe. 

C



Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 02, 2010, 03:41:11 PM
It works..  I ended up putting the HV through my Eico resistor box  I turned the dial until I got a solid 148 volts DC at the OA2 under load.. The tube fired off around 200 volts in.  There is already a Big power resistor there so I left it alone.  250 IN, 148 solid at the oa2.    This worked out to be around 7K resistance.  I put this resistor in the transmitter on an unused pin and then updated the manual. I think 360 would have been just to much. It was showing 415 in tune mode. 

Its not very stable on the freq meter but the Power out is rock soldi 20 watts.  I think its going to be good to go once I get all the covers back on. The VFO is apart on the bench. 

Now.. What do I do with the cathode key wire?   Hook it to the dowkey with a Ground return?  The Dowkey keys up in tune and in operate.  The Globe has no relay inside and it has no provisions for keying up this VFO.

Since the B+ is not active in standby. It seems to me, that I can just ground this wire in the VFO and then rely on B+ to start the VFO up. 

Agreed?
C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 02, 2010, 06:20:28 PM
The signal is not strong enough.  Its very hard to find the peak. Its very hard to tune. I replaced the signal cable with a new 2 ft long piece thinking that would help. Its just not enough Drive out of the VFO.

The tube is good. The oa2 is good. If I put a counter on the output of the VFO, the signal is there on the counter. If I plug it into the Globe transmitter, I cant get a good enough peak on the osc meter.

Anyone have any suggestions? Maybe swap the 6BH6 out for another tube with more gain?

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 02, 2010, 07:26:49 PM
Clark,

The circuit you describe sounds like the 6N2 VFO less the switching for dual bands.  The manual is on Bama and it will be helpful for you.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 02, 2010, 07:45:13 PM
Yeah. I downloaded it last week. It was helpfull. 

I have it up and running.  All voltages check. The VFo outputs 8.222 like I set it for.  Its solid output.  When I remove the Xtal from the globe,  insert the cable to the VFO socket. There simply is no signal.  It wont kick the Globe over. At one point, i had it working but its now wont start the globe to oscilate.

I even changed the series Cap up and down and put a variable in. I cannot get it to lock and stay with the VFO.

Going to walk away from it for a while... and think about what it could be.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 02, 2010, 11:47:31 PM
Thanks for your reply..

I tried TWO VFOs. A Globe 6 and 2 and now this Johnson. Both output on 8mhz.  Both show this on the counter. I have an 8.222 xtal. The radio works fine with the xtal.

BOTH vfos do not show any OSC on the meter.. NO rise.  I have changed caps. At one point, I had it working.  But now nothing. I have checked or changed every cap in the VFOs.  I even replaced the cables.

For some reason. These VFos wont drive the old Globe transmitter.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 03, 2010, 07:02:43 AM
Clark,

Does your WRL transmitter need any circuit switchover or modification to work with a VFO instead of a crystal?  Generally the cathode RF choke is shorted to convert an oscillator over to buffer/doubler operation.

The cathode keying line in the Johnson VFO must be grounded for operation and also make sure that the "hot" side of the VFO output is fed to the proper side of the crystal socket.   

How long is the output cable from the VFO?  The WRL transmitter may be sensitive to excess capacitance from the cable length.

I use the similar Johnson 6N2 VFO with my 6N2 transmitter and it has no problem driving it.  The 6N2 uses one section of a 6U8 as an oscillator which acts as a buffer/doubler when driven by the VFO.  I have never tried any of the WRL/Globe VHF gear so I don't know anything about the exciter stage of your rig.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WU2D on April 03, 2010, 09:04:10 AM
Rodger is hitting the mark on this one - check that stuff out. A crystal oscillator circuit is not a happy and efficient amplifier or multiplier unless you do what he says (set it up for amplifier mode). Alternatively you can drive the P out of it with another stage like a class A amplifier like another 6AU6, 6BH6 or 6AG7 etc... and usually get the stage to multiply effectively.

Mike WU2D


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 02:20:43 AM
I need to scan the schematic so you guys can see this osc.  I have hooked teh VFO up to the transmitter again with my probe on the xtal socket. The VFO is showing 8222 right there at the socket. But I still cant get any OSC rise when tuning. I am sure this is something simple.

There is no switch to VFO mode.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 01:31:30 PM
GUys. Thanks alot for the help.  I am going to work on the thing today.  The Xtal socket is NOT grounded. The left side runs right to the tube pin and the right side goes to a 50 PF cap and then to another tube pin.  I was told this is cathode doubling or something along those lines...

I will look for a resistor!

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 02:45:46 PM
I spent some time with it on the bench again.

I set the VFOs output to 8.222 the same as my working Xtal.

I hook the VFO up and attempt to tune the osc. No bump on the needed.  Big bump on the xtal.

I have read the output of the VFO during the tune up. Its there.. 

The LEFT side xtal connection goes to Pin 8-9 on the schematic.  There is a 100K resistor on the schematic. Radio does not have one.

The right side xtal goes to a terminal strip. Then through a 50pf cap to pin 7 of the 5763 tube.

There isa 47K resistor from ground to Pin 7. But that resistor does not appear on the schematic. I jumped it out and the rig stopped working all together. No xtal or vfo.

Maybe I should try adding the 100K back in?  Maybe someone ripped it out..  Its clearly NOT in the radio

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 04, 2010, 02:56:30 PM
Maybe you should review the VFO circuit for the WRL 6 & 2 VFO (compare Johnson VFO to Globe VFO) that was designed to work  with the Hi-Bander.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 03:04:33 PM
I have the WRL VFO.. It does not work either. 

To review..

The transmitter works FB with the Xtal installed.

The Johnson VFO and the Globe both output on my counter right where I want them.

No Rise in OSC current with either VFO. 

I put the 100K in. No change at all. 

I retuned the slug. I got some output.. about 2 watts with the VFO working.  Counter was bouncing around the area that I need it to be on but not stable.

Anyone have any other ideas here?

Thanks for all the help. I am sure there is something simple that is preventing the VFOs From driving this osc arrangment.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 03:20:16 PM
Thanks for posting the schematic. I will sit down and compare.  Lots of different parts here. ...

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 03:22:33 PM
That 6 and 2 is very different.  None of the first half is even close to the hibander schematic. It would be a complete rebuild to get it to function like that. 

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 04, 2010, 03:46:38 PM
Clark,

When you get a chance, post the schematic of your transmitter (at least the oscillator/buffer/multiplier).

The 6N2 works well but I wouldn't want to rebuild your WRL to match it :)


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 04:08:20 PM
Yeah.. I am going to have to go buy a new scanner/printer.  Mine crapped out.  Let me take a photo of it real fast.


Try this...


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 04, 2010, 04:28:51 PM
Clark,

 
Make sure the hot side of the 6N2 VFO is connected to the side of the crystal socket going to the grid and temporarily short across L1 (use a short piece of wire tack soldered in place).

This should allow the oscillator stage to operate properly as a buffer for the VFO.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 04:44:45 PM
No change with L1 shorted.  Tuned up the rig with the xtal.  removed Xtal, Put VFO cable into Xtal socket, Shorted L1. No peak. I went across L1s terminals with a wire.  Also tried shorting L1 and the resistor after L1.  No peak on osc. Tuned it full around over and over.  Flipped the Xtal socket around. No change. 

Put xtal back in, Rig tuned right up.

Had Probe of Counter on the xtal socket. The VFO is showing 8.3 right there at the radio. When I unkey the VFo looses B+ and the signal goes away.  VFO appears to be working.  Radio will not show any OSC current with the VFO connected.

Any other ideas?

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 04, 2010, 04:55:49 PM
Clark,

What does your manual say about the frequency multiplication circuitry-specifically what is the proper frequency input to the first multiplier stage?  Is the VHF 62 doubling in the oscillator stage when it uses a crystal?  What does the manual say about using a VFO for drive?

The VFO should have plenty of drive but if the oscillator stage normally doubles it will be on the wrong frequency.

At this point a scope would also come in very handy.



Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 05:22:59 PM
The Xtal is 8.222  This gets me 18 times over.

It works FB with the xtal.  I have the matching Globe 6-2 VFO.  It does not work either. I just dont understand why it wont work. Maybe I need the manual for the Globe VFO... Anyone have it?

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 05:38:19 PM
Update..

Plugged the Globe VFO in and tried it out again.

Tuned rig up to full output power with Xtal. 

Put Freq probe on Globe VFO.  Shorted Key jack. It has a stable 8.222 right out.. nice and strong.

Put that into the Globe and BINGO!  I have osc rise.. nice and strong. 

But now I cant get the Buffer knob to tune.. No change in buffer current.. and as a result of that. There is no Final Grid current and no power.

When keyed up, The counter reads 21mhz...   I tuned L1 with no luck.  Shorted L1 and the osc current goes away.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: WQ9E on April 04, 2010, 05:41:43 PM
Clark,

But what does the manual say for output frequency from the first stage?

Did you try the Globe VFO with the choke in the cathode lead still shorted?  If neither VFO works then I would suspect the transmitter instead of the both VFOs.

How do the voltages look on the oscillator stage according to those called for in the manual?  Have you tried a replacement tube for this stage?


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 06:03:06 PM
In the manual to the transmitter.. It says.

XTAL or VFO. 8 to 9 MHZ. 

Then it says:

OSC control.  Tunes the oscilator plate to the third harmonic of the Xtal or VFO input.

BUFF control.  Tunes the buffer plateto the oscilater FREQ OR uses the Third harmonic of the oscilator to ouput FREQ.

I set the VFO to 8.0222 where I need it.  This matches the xtal. There is no Osc rise. Its like the VFO is not even plugged in.  Very odd. 

This vfo was marketed to sit next to this damn Transmitter.. It has to work.  What boggles the mind is why it works with an Xtal and no the vfo. 

I know the VFO is outputing.. The SX28 in the other room can hear the VFO 15 feet away as I tune it.  So I have confirmed this VFo to be working..

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 06:13:04 PM
Why is that a problem?  The VFo and the Xtal match on the input side.   

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 07:07:22 PM
I dont own a 6n2 vfo. 

I have a Johnson 2 meter VFO and a Gobe 6-2 VFO. 

I guess the 6n2 works like the others.  I wonder why globe sold this VFO to sit next to the Transmitter when its not compatible. 

I guess it wont work unless anyone has a simple solution.  I guess I will order more xtals.  The one I ordered is a full 8KC down from the net Frequency. Even with a trimmer, Its still 6 KC off before it unlocks.  Maybe I will have better luck with the next xtal

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 04, 2010, 07:32:41 PM
Thanks for the picture. Now I understand. This one is exactly like that but has no 6 meter.

The Globe Version that does have 2 meter and 6 meter is working FB.  I just looked at the output. The harmonics are low. It has an output filter.  Maybe its made to work with a different model Globe transmitter. 

I think we got to the bottom of this one!  Thanks to everyone who helped out.  I sure learned alot of oscilators. I have been reading books for days and days..  :(

Its just my luck that I buy the only 2 meter rig out there that wont work with these VFos.  I guess its time to order yet another xtal.  Maybe I will get closer this time.

I will sell off the Globe 6-2 VFO and the Johnson 2 meter VFO. If anyone wants either, Let me know. I will pass them on for the price I paid.  They are of no use to me now.

Clark


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 05, 2010, 03:04:31 AM
Thanks for the picture. Now I understand. This one is exactly like that but has no 6 meter.

The Globe Version that does have 2 meter and 6 meter is working FB.  I just looked at the output. The harmonics are low. It has an output filter.  Maybe its made to work with a different model Globe transmitter. 

I think we got to the bottom of this one!  Thanks to everyone who helped out.  I sure learned alot of oscilators. I have been reading books for days and days..  :(

Its just my luck that I buy the only 2 meter rig out there that wont work with these VFos.  I guess its time to order yet another xtal.  Maybe I will get closer this time.

I will sell off the Globe 6-2 VFO and the Johnson 2 meter VFO. If anyone wants either, Let me know. I will pass them on for the price I paid.  They are of no use to me now.

Clark

The Globe VFO manual says that the unit was primarily designed for use with the Globe Scout 680-A and the Globe Hi-Bander VHF-62 or any 6 and 2 meter transmitter with suitable multiplier stages.

In the Hi-Bander manual, page 7, Section 3-4, discusses "use with VFO". Page 8 discusses a modification to Hi-Bander transmitters with Serial Numbers beginning with IH, JH, and KH. It requires adding a 10 pf cap between the shield of the coax and the cold end pin of the crystal plug.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 05, 2010, 01:51:03 PM

It requires adding a 10 pf cap between the shield of the coax and the cold end pin of the crystal plug.


He might be able to do that to the Johnson VFO as well, but the harmonic levels may still be too low. It's worth a try though.

Even if it doesn't work with his Johnson, his Globe 6-2 VFO isn't working with the Hi-Bander either so try it on that one.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 10:42:24 AM
My manual does not mention anything about a modification for use with VFO.

I dont understand what you mean by Cold pin.  Are you saying a cap across the VFO output cable?

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 01:10:30 PM
This transmitter has no cold side.  Both leads go to the tube.  Sorry for not mentioning that.  I guess I will try the lead that goes tot the cathode.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 06, 2010, 01:42:07 PM
If you read the Hi-Bander manual, there is a section 3-4 on Page 7 that explains connector of VFO to the rig. Connect center conductor of VFO output cable to the XTAL socket hole nearest to the METER SWITCH. The shield braid of the cable connects to the remaining XTAL socket hole. Page 8 explains the modification I mentioned previously.

Complete manuals are wonderful additions to any rig  8)


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 02:28:51 PM
I have the manual.  Its from AG tennenbaum.  To bad it does not say anything about this.  I dont have a 10 PF cap.. I have a 20. I will try it in a few minutes after the 40 meter meter group.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 03:18:08 PM
Cap did not work. I tried 5 to 50 pf at the Xtal plug.  I unscrewed the shield from the Xtal plug. Put the cap inline. No rise in current on the osc. 

What a real pain the ass.  Two VFos and a radio.. hours of work. Damn thing wont oscilate.  Oh well. Going to toss it all in the Dumpster.  Thanks for the help guys. I learned alot.  I would wish leo was alive. I would smack his face for making a radio with a tripler in the first stage. What an A-hole. :-\

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 04:30:23 PM
There is no shield.  There are two wires. Black goes to Cathode on tube. Green goes to Grid.  Its not shielded anywhere. I can try it at the tube pin if you think that might help.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 06, 2010, 06:00:54 PM
Get the Globe VFO to work with the Hi-Bander first since it was designed to work with it. Put the Johnson aside until you get the other combo working. This way we all will be on the same page.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 06:21:45 PM
Its an RCA jack on the back of the VFO. I used an old Collins S line cable. Its coax.  Not sure of the type. Its the type of cable used to link the S lines together. someone cut the end off so I used it.

Its about 2 feet long. Maybe 3. 

The johnson had a piece of RG58 on it.  About 3 ft. 

What I was saying about no shield was about the Transmitter. The Xtal plug on the inside has two wires. No shield and no ground. Both pins are go to the OSC tube.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 06, 2010, 09:34:53 PM
tried 75 ohm and 50 ohm coax.  1 ft.  No osc current.  Measured it on the scope. Its a full 10.2 volts output of that VFO cable right into the radio. I can see the VFO signal right at the tube pin. 

It simply will not work.  Pull the VFO line out and put the Xtal in.  It works FB. Full power, Great sound.. Just off 8 damn KC.

To bad. The net starts in 30 minutes.  We all tried our best here. Thanks for all the time guys.

 I have now measured and checked every part in this radio and TWO VFOs.  Nothing at this point will get my 10 hours back. I am going to take it to the range tomorrow and pump the damn thing with lead. Maybe I can get some laughs out of it. I need to shoot my New PPS anyways. 

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Jim, W5JO on April 06, 2010, 09:41:22 PM
Did you feed the VFOs output into a counter to see what frequency they produced?  Use a scope probe (appropriate freq. response) and measre it.  I am curisous to see what you read.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 06, 2010, 11:48:30 PM
While looking at the front panel of the Hi-Bander, the center lead of the coax from the Globe VFO connects to the right pin (this pin connects to the grid). Take a short clip lead and just connect the coax shield to ground. Check and see if the two screws holding the crystal socket in place are at chassis ground, and, if so, connect the shield/short clip lead to one of them. You may or may not have to connect a 10 pf or so capacitor from the right pin (where you connected the center conductor of the coax) to the other pin of the crystal socket. Coax cable length from the VFO to the Hi-Bander probably should be around 2 feet or less.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 07, 2010, 07:50:05 PM
Pete. That made the stage a doubler.  16mhz out and then the buffer would not tune.

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 07, 2010, 08:15:07 PM
No reason for it to become a doubler unless L1, or more likely L2, is not adjusted properly.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 07, 2010, 08:20:26 PM
Both of these are adjusted perfect with the Xtal working.  Should I try to adjust them for the VFO?

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Pete, WA2CWA on April 07, 2010, 08:31:41 PM
The L1 adjustment was installed to reduce or eliminate CW chirp. However, to far in either direction would cause the oscillator to stop oscillating. L2, on the plate side of the 5763, should be roughly tuned to 25 mHz. Did you also include the 10 pf cap across the crystal socket pins although I don't see where that would make much difference?


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 07, 2010, 09:53:30 PM
Yes. I get osc, buffer, and final current. But the rig outputs on 23MHZ.  Low power. About 5 watts.  Tuned L1 and L2. No change. 

Put the xtal back in, Tuned rig up 20 watts out on 144.444. 

I dont understand why its going to 23. 

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 07, 2010, 10:27:18 PM
Yes.. Sorry

I did try the cap in series. No Osc dip.

I also tried pulling the RCA out so just the center was in.  I tried Grounding the shield with and without the cap and no ground at all.  I also tried to put the cap across the socket.

I have the Freq counter on a Probe.  It shows a solid 10 volts at 8.0222 where I need it.  ITs actualy stable. Same Freq as the Xtal. I backed the slug out and rotated it in.  I can get a peak but its not the right one. There is no activity on the osc meter with any other slug position.

I keep thinking the trouble is that both xtal socket wires go to the tube. Other schematics dont show this.  They show one grounded.
C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: ke7trp on April 07, 2010, 11:05:36 PM
I will take my WB reciever in the shop and tune around until I hear the third. 

C


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Jim, W5JO on April 07, 2010, 11:41:20 PM
Use the counter with the Oscope probe to read the frequency of each stage in the transmitter.


Title: Re: Info or manual needed. Johnson 2 meter VFO (mobile)
Post by: Jim, W5JO on April 08, 2010, 05:40:20 PM
Use the counter with the Oscope probe to read the frequency of each stage in the transmitter.

His transmitter is working with the 8.2Mc xtal so it’s not the radio, but as his manual states the oscillator tunes to the 3rd harmonic of that xtal or VFO.

Another idea would be to use a 10 meter rig that goes up high enough with some attenuation and use it instead of the VFO.

Clark, it wouldn’t hurt to try and reconfigure the input of that oscillator stage like the 6N2 with the grounds and see what happens. If it didn’t work at least it would rule that out.

But I am curious as to the frequency and RF voltage level is present at the grid of the first stage and the grid of the second stage.
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