Johnson Five Hundred

[k7iou]

I ran across one of these rare beauties and had several questions.
Current value? I only saw 1 on QRZ listed for $2500.
Known problems?
Eham had several listed in reviews and they seemed minor.
Any Five Hundred owners out there?
Earth calling Mars......CQ CQ de k7iou  

Took both units apart for examination & cleaning.
What do you think?
More picks below!

[N8ETQ]

  Nice Find!!

    Had a customer pass a couple 3 of those through my
place about this time last year. He had 1 with P. Sup. that
worked just fine. He asked me to check the other 2 out
with the supply, and they were also OK.

   then he asked me to lash up a supply Modulator
deck with cables so he could use one, I think he sold the
complete one at Dayton last year.

    Anyway, I lashed up the supply/Modulator and made
a complete set of cables for the guy and It worked out
real well. Here is a pix of the thing running of the HB supply.

GL  That's a Keeper!

/Dan

[WD8KDG]

One of those followed me home in late 2004. No cables, no key, RF section not too bad, PS/Mudulater was a WTF. Purchase price + repairs, some new iron & stuff came to over $3K.

So ifen every thing works on all bands, I understand current prices. Ifen it don't work YMMV.

Craig,

PS: The Junkston "500" is a good TX.

[W3GMS]

It appears the condition of that one is very good.  At least from the outside.  The price seems about right from what I see them selling for these days.  Actually the Johnson Desk KW's can be picked up for less than the Johnson 500's.  Whats nice, its a self contained transmitter with a separate P.S. / modulator.   Pick yourself out a good receiver and away you go with a first class AM station.   

I bought mine many years ago from a good friend and he was kind to me with the price.  $500.00 in mint condition but those situations seldom happen and this was 20 some years ago.  He was the same friend that wanted my HQ-170 in the worst way.  I did not have  a second one and told him I would find him one.  Nope, he wanted mine.  So he called me up and asked if I wanted a Collins KWS-1 and then said he would trade me his KWS1 for my HQ-170!  I put the receiver in the car so fast and it was a done deal about 30 minutes later!  As my luck runs very well on these kind of things, a friend called me up a few weeks after my 170 left and offered me his in the original box and just in pristine shape as a gift!   

Joe, W3GMS         

[N8ETQ]

   Yeah, there going for big bucks now a days, my
customer had a well equipped Junque box and we used
all of the Iron from it. A Clegg Zues mod and
plate xfmr. He even supplied a military FSK device
we stripped for the chassis.  Copied the original
layout right out of the manual.  Worked fine.

/Dan

[Pete, WA2CWA]

Back in the late 90's, saw two of these at a CB'ers house totally disassembled and parts laying all over the cellar floor. Some individual parts were being sold on ebay; the rest to the scrap-man.

[WQ9E]

I have had one many years and it has been quite reliable.  The only problem I found was with the "mechanical delay" relay which controls the external antenna relay.  It is supposed to provide a slight delay on PTT release to prevent hot switching but this delay appears to go away with age.  When this happens, if your gaps are properly adjusted, they will arc intermittently on PTT release.  If you follow the manual instructions to widen the gaps then the arc will be at the much maligned connectors on the back which work just fine if the relay is working as it should.  If you have the gap opened too wide and follow one of the websites that tells you to replace the connectors because of flash over then the arc will find a new place and that one might be expensive

The simple expedient of putting a small electrolytic cap and isolating diode across the mechanical delay relay coil will make the issue go away.

My Viking 500 cost $800 but that was 8 years ago.

[VE3AJM]

I've owned my 500 since 1994.

The tip jacks on both the RF deck and the modulator/PS were a problem in mine, as well as replacing the cabling between the two units. The cable was brittle. The tip jacks/plugs that carry the modulated B+ broke down/arced. So I replaced them with Millen HV connectors at both ends, and just replaced the other tip jacks/plugs with NOS Johnson units.

I built a platform for the PS/modulator to sit on, and put some good quality casters underneath. It makes it a lot easier to move around, rather than just trying to use those suicide handles on the sides of the chassis.

Al VE3AJM

[WA5VGO]

I hate to get off topic but I have a question for some of the owners out there.  Mine has a slight backwave when it is unkeyed on AM. It doesn't hurt anything and I've never been able to find anything wrong. I have made changes to insure that RY-302 releases last and the PA is perfectly neutralized. Is this normal, or do I need to keep looking?

73,
Darrell

[W3GMS]

I hate to get off topic but I have a question for some of the owners out there.  Mine has a slight backwave when it is unkeyed on AM. It doesn't hurt anything and I've never been able to find anything wrong. I have made changes to insure that RY-302 releases last and the PA is perfectly neutralized. Is this normal, or do I need to keep looking?

73,
Darrell

Darrell,
I have not been in mine in a long time, but if its like the later Ranger's with a keyer tube, there is a pot on the chassis for that tube that controls when the tube goes into conduction.  If its not set correctly, the VFO will be on the verge of running even when the transmitter is in the stby position.  The purpose of the tube is to control the CW keying but if its not set correctly the tube will drag a bit as its going out of conduction.
Joe, W3GMS 

[WQ9E]

Darrell,

As Joe stated the VFO is held on for a moment after  the key/PTT is released so that a transmitted chirp doesn't occur and if it isn't adjusted properly the VFO will stay keyed.  Do you just hear a weak back wave in your receiver from just the VFO (and not the entire RF chain) staying active.

It is the same circuit as used in the Ranger and Valiant.  If it can't be adjusted to release the VFO there are three capacitors in the circuit and if they become leaky they will cause the keyer to hang.  One is a .005 and the other two are .22 caps. I am looking at a crappy copy of the schematic on my computer and it looks like C150, C151, and C106 but without my original manual I am not absolutely sure on those part numbers.

[k7iou]

Wow, so many replies and great stories! I plan on building a platform with casters for the power supply. I experienced the suicide handles firsthand and good thing for carpeting! Almost broke my hand when we picked it up off the carpet and it did a 180. Whew!
Keep the Five Hundred stories coming!

[Opcom]

I submit a handy survey of spring and fall 2013 ebay prices.
By no means complete considering it takes about 2 days to do a full one as in this one's Fall section, and there's no five hundred in it, but it may help future inquiries.

[VE3AJM]

You can insert an approx 10H choke inline with the PA screen tip jacks. When you get the tx going I could notice the VR tube string on the PS/modulator igniting on voice peaks, limiting the modulating of the screen voltage. Adding the choke allows the screen to modulate  and no clamping action from the VRs.

Al VE3AJM

[WD8KDG]

You can insert an approx 10H choke inline with the PA screen tip jacks. When you get the tx going I could notice the VR tube string on the PS/modulator igniting on voice peaks, limiting the modulating of the screen voltage. Adding the choke allows the screen to modulate  and no clamping action from the VRs.

Al VE3AJM

Please pardon the question: No intent to hijack the thread.

Anyone else seeing color on the VR tubes in AM mode? I thunk they were for the SSB mode? With that, is your clamp tube adjustment & screen voltage correct. The screen voltage dropping resistors should be set around/just about 38K ohms.

Craig,

[WQ9E]

Craig,

I have never seen this in mine either and Johnson states explicitly in 8.,a., p22 that this should not happen.

If it were happening in mine I would check the unmodulated screen voltage to see if it is high already.

[k7iou]

More pictures!

[k7iou]

Has the audio & power supply mod.

[k7iou]

I noticed a missing shield? In the transmitter by the transformer.
Not sure it's suppose to have this one?
Anyone know the screw size for the upper cabinet on the power supply?
Thanks

[Dave K6XYZ]

My 500 has a shield installed on that tube.
Any tube socket of that type indicates that a shield is supposed to be installed.

A really nice looking 500!!
The original HV transformer was a dud and most were replaced by Johnson with the Thunderbolt transformer.
Yours looks original to me...ie...my Thunderbolt transformer looks different.
I can't see the part number right now.

edit....the wires to the rectifiers diodes come out of the top of the Thunderbolt transformer.

73

Dave

[W3RSW]

Nice rig.

Oh, I've been meaning to ask for years.

What's that little clip sticking out of the back of the plate tuning cap for?

I have a couple with the same clip.

[Opcom]

Does it use an external  plate supply? The transformer in the pic does not seem too big.

[k7iou]

Yes, it uses an external supply.

[W1KSZ]

Where do you guys find this stuff !!

It looks very clean and if I had it, it would be a definite keeper.

You got the "Holy Grail" of AM Transmitters and a side benefit, it
will keep the house from floating away in a flood !!

73, Dick

[k7iou]

Thanks Dick, P/S weighs in at a light 120#'s . I am afraid it will crack the concrete!