Globe King 500 & subbing 1N2637 for 866

[K4RT]

Any Globe King 500 owners here using 1N2637 solid state rectifiers in place of the 866 mercury vapor rectifiers? Do they fit beneath the modulator deck?  I found measurements for the SS unit on line and I think the spacing might be tight in the GK 500.  I'm not certain I want to replace the 866's with SS but if 1N2637's won't fit under there there's no point in considering them.  Also, if you're using 1N2637's what increase, if any, in the B+ do you see compared to 866's?

Happy new year!

Brad K4RT

[WD4LUR]

Brad,

I just looked up the 1N2637 and it claimed the overall height including the pins is 5.04 inches.
See https://www.radiomuseum.org/tubes/tube_1n2637.html

According to the RCA data sheet for the 866A, the overall height including pins is 6 9⁄16 inches. So, it looks like it should be okay.
Also, you have to take into account that the tube sockets for the 866A's are recessed below the chassis a little

Hope this helps.
Dan
WD4LUR

[Jim, W5JO]

Been using them for years.  I also disconnected the filament transformer for the rectifier tubes.  No problems at all.

[W7TFO]

I was going to save this till April:

The ultraviolet from the glow of MV rectifiers kills virus in the shack.

Thereby, solid state is unhealthy.

73DG

[KC2ZFA]

are the SSDI 7850 and SSDI 7927 sticks
similar to the 1N2637 ?

it was easy to find info for the 2637 but
nothing about the SSDI sticks that also
have “FAA TA10KV” in their label.

[w8khk]

I was going to save this till April:

The ultraviolet from the glow of MV rectifiers kills virus in the shack.

Thereby, solid state is unhealthy.

73DG

Why wait until April to help your fellow hams stay healthy?  Another often ignored issue when solid-stating the supply is the corona discharge released around the tube sockets due to the increased voltage.  That and NOT controlling the virus adds up to a very dangerous combination.  Hi HI!  Long Live the 866A and 872A!  Such a beautiful and healthy glow.  What's not to love?

[Jim, W5JO]

I was going to save this till April:

The ultraviolet from the glow of MV rectifiers kills virus in the shack.

Thereby, solid state is unhealthy.

73DG

Why wait until April to help your fellow hams stay healthy?  Another often ignored issue when solid-stating the supply is the corona discharge released around the tube sockets due to the increased voltage.  That and NOT controlling the virus adds up to a very dangerous combination.  Hi HI!  Long Live the 866A and 872A!  Such a beautiful and healthy glow.  What's not to love?

The voltage drop across those diodes takes care of most of that

[K4RT]

Thank you all for your replies.

Dan, thanks for posting that link. I saw that web page but until you mentioned it, I had forgotten that the 866 sockets are recessed. I was able to get behind there with a tape measure this morning and, as you and Jim already know, I found that there's sufficient room. I have seen the FAA designation ZFA mentioned but I'm not sure it's the same device. As an aside, after I posted, I found this data sheet which may be of interest:

https://www.kevinchant.com/uploads/7/1/0/8/7108231/international_rectifier_ss_replacements.pdf

When I bought my 500B it was in working order. However, after a period of non-use now it won't tune up properly and the 4-250 screen voltage is low even though the B+ is normal, so I will be examining the screen voltage branch to try to find a problem.

Brad K4RT

[Jim, W5JO]

When I bought my 500B it was in working order. However, after a period of non-use now it won't tune up properly and the 4-250 screen voltage is low even though the B+ is normal, so I will be examining the screen voltage branch to try to find a problem.

Brad K4RT

Check the 5Y3 and relay contacts in line with the screen.

[KC2ZFA]

Brad, I think the only difference between the 10 kV SSDI sticks and the 2637
is the current rating…250 mA for the 2637, unknown for the SSDI sticks.

It would be great if someone could shed some light on the 10 kV SSDI FAA sticks.

Peter

[Pete, WA2CWA]

Brad, I think the only difference between the 10 kV SSDI sticks and the 2637
is the current rating…250 mA for the 2637, unknown for the SSDI sticks.

It would be great if someone could shed some light on the 10 kV SSDI FAA sticks.

Peter

what do these SSDI things look like
google of ssdi just brings up social security info
ssdi is not triggering any brain cells

[WD4LUR]

I found this place to buy the SSDI 7919 TA10KV rectifiers, but couldn't find a data sheet.

https://www.xcqdjx.com/archive/Ssdi-7919-Replacement-Rectifier-Faa-Ta10kv-22/umw4535479827a3.html

Dan

[Jim, W5JO]

Some info for you.  

Note the 1N2637 are more than adequate for the GK 500

[KC2ZFA]

the attachment above disagrees with the kevinchant doc posted further
up when it comes to max output current.

as for the socsec rectifiers, the SSDI ones are a couple of millimeters
taller than the 2637.

[K4RT]

Check the 5Y3 and relay contacts in line with the screen.

Thanks Jim. The screen supply output was low so I replaced C25 and C26 a couple weeks ago and it's now 486 VDC, but at the 4-250 screen it's 159 VDC so something is pulling it down. Next, I'll take voltage readings at the relay, switch, and various components between C26 and the screen.

Peter, I haven't found a spec sheet for the SSDI rectifiers yet.

Brad

[Jim, W5JO]

The screen supply output was low so I replaced C25 and C26 a couple weeks ago and it's now 486 VDC, but at the 4-250 screen it's 159 VDC so something is pulling it down. Next, I'll take voltage readings at the relay, switch, and various components between C26 and the screen.

Brad
[/quote

Don't forget that the final tube may have a problem.  That happened to me recently and voltages weren't correct.  Turned out the tube had gone South.

Has the value of R24, the bleeder, changed?  The resistor R21 could have gone high, it gets pretty hot.  I replaced mine with a 2 watt.  And, of course, the meter resistor R22 should be a 2 watt also.

[K4RT]

Don't forget that the final tube may have a problem.  That happened to me recently and voltages weren't correct.  Turned out the tube had gone South.

Has the value of R24, the bleeder, changed?  The resistor R21 could have gone high, it gets pretty hot.  I replaced mine with a 2 watt.  And, of course, the meter resistor R22 should be a 2 watt also.

Thanks Jim. I noted on the RF deck schematic that R24 measured 49.7K, R21, a 56 ohm 1 W resistor, measured 58 ohms, and R22, a 22ohm 1W resistor, measured 24 ohms. The other components in the screen supply checked out but I'll go through that section again and take voltage measurements. I have a spare 4-250 and I'm seeing the same thing with the spare.

[Jim, W5JO]

Thanks Jim. I noted on the RF deck schematic that R24 measured 49.7K, R21, a 56 ohm 1 W resistor, measured 58 ohms, and R22, a 22ohm 1W resistor, measured 24 ohms. The other components in the screen supply checked out but I'll go through that section again and take voltage measurements. I have a spare 4-250 and I'm seeing the same thing with the spare.

Have you checked the resistance of the choke and found it ok?  The tube socket is OK?  If all else, relay contacts and such are ok then I would suspect the transformer.  When checking is the mode switch in tune or the CW or AM mode? 

[K4RT]

Have you checked the resistance of the choke and found it ok?  The tube socket is OK?  If all else, relay contacts and such are ok then I would suspect the transformer.  When checking is the mode switch in tune or the CW or AM mode? 

So far I have attempted tune up only in CW mode. The resistance of choke CH1 measured 553 ohms and no short to chassis indicated. I believe the tube socket and Relay 1 are ok but I will check them again.

[WBear2GCR]

I found this place to buy the SSDI 7919 TA10KV rectifiers, but couldn't find a data sheet.

https://www.xcqdjx.com/archive/Ssdi-7919-Replacement-Rectifier-Faa-Ta10kv-22/umw4535479827a3.html

Dan

The site appears to be "fishy".
Registered to Alibaba in China, and full of stuff, that I doubt exists.
Also, the address shown is apparently a Staples store?

The text on one description says something about "ebay mouseover" for the picture zoom... odd. 

Caveat Emptor.

Too bad.

                     _-_-bear

[WD4LUR]

Yeah, that is a shame!

[K4RT]

Peter, my search for data sheets for SSDI 7850 and SSDI 7927 rectifiers turned up nothing. So far I have found no cross reference to a known rectifier such as 1N. I was thinking these might be one-off products for an FAA contract for which few were made but searching an auction site they seem to be plentiful.

[Dave K6XYZ]

I found this place to buy the SSDI 7919 TA10KV rectifiers, but couldn't find a data sheet.

https://www.xcqdjx.com/archive/Ssdi-7919-Replacement-Rectifier-Faa-Ta10kv-22/umw4535479827a3.html

Dan

The site appears to be "fishy".
Registered to Alibaba in China, and full of stuff, that I doubt exists.
Also, the address shown is apparently a Staples store?

The text on one description says something about "ebay mouseover" for the picture zoom... odd. 

Caveat Emptor.

Too bad.

                     _-_-bear

Yeah....I've been looking at that since yesterday.
Don't think it is a Staples store.....they spell it as Staplees.
Google maps can't find it either because the address does not state a city....looks like the zip is bogus too.
Too bad....the 'price' is pretty good!!

I have SSDI FAA 7850 sticks in one of my Viking 500 tx.....but I don't have any idea what the ratings are other than 10kv.
They have been working fine for about 8 years and for the previous owner.

I looked at the Solid State Device Inc. (SSDI) website and this many years later is not showing any of the numbers we have been discussing or any 866/3B28 socket style device.
I also noticed the discrepancy in the current handling of the same diode on those two charts....weird.

[KC2ZFA]

250 vs 750…to separate the optimists from the pessimists 

you will need at least a resistive step-start to limit inrush current
if you don’t use a surge resistor.

[K4RT]

Do you test a 1N2637 in-circuit? Can a HV SS rectifier be checked to see if it is intact using a DMM?