Collins S-Line Mostly Returns

A load of Collins S-Line gear

After MUCH work and TLC by Chuck W9KR, the majority of both of my Collins S-Line stations was ready to pick up.

The 32s1 transmitter is only major piece left behind for final work, as it hasn’t been behaving as expected on each band.

On a temporary basis the RE (Round Emblem) late production transceiver – KWM-2/A with 321B5 Second VFO – and station components (30L1 Amp, 516F2 Power Supply and so on..) will be set up where my Flex-6600M runs. This will let me work the rig lunch hours and after work, as I would like to let the station run for a bit before hauling it out to Washington Island.

I’ll do the same with the 32s1/75s1/30L1/312B4/516F2 WE (Winged Emblem) station when the transmitter is done.

The work Chuck W9KR did is monumental. Recapped, Upgraded, New tubes as required, new parts as required, decades of dust & grime removed, New 572b tubes, in certain cases mouse infestations sign removed, tech bulletin upgrades, CCA upgrades, and a few Chuck W9KR upgrades – especially in improving the reliability of the 516F2 power supplies.

The gear arguably should work better than when new, should be reliable and should have all that great Collins sound.

Quietly I cannot say enough with the detective work and bench work of Chuck W9KR.  I realize that I have so much to learn just in order to fully understand all the goodness he baked into these radios.

Lots of Collins fun ahead for me working the airwaves with refreshed vintage gear!

73

Steve
K9ZW

Handling the Voltage Multiplier Issues with High Line Voltage and Vintage Radios

What is “normal” household line voltage?

What is acceptable to our Vintage Radios?

Without getting into a deep discussion the voltage delivered to the average American home has gone up since the pre-WWII’s 110vac, then post-war 117vac is now 120vac.

The current standards are:

Yet our old radios might be intended for less.

My two Collin’s S-Line Stations definitely were intended for a bit lower voltage than 120vac.

Inside the S-Line components voltage can be multiplied to produce Vacuum Tube level voltages by step-up transformers.

If the original design took say 110vac and upped it to 800vac, it is a 7.273 multiplier.  (The 800vac is just a value I picked, as there are several stepped-up voltages in use in a S-Line station.)

If modern power is suddenly say the maximum allowable of 120vac  plus 6% for 127.2vac, the 7.273 step-up transformer is pushing out 925vac, which may be above the maximum safe voltage for a particular application.  Even a 120vac line voltage will he 873vac after the step-up.

What the Collins designer originally really wanted was that 800vac voltage they designed for, which would mean we have to figure out a way to limit the line voltage to 110vac.

Well you cannot call up your power company, as ask them to “turn my voltage down for me, guys” That isn’t going to get you anywhere.

Here is the solution:

Actually what is in those boxes are these:

Medium Duty Variac Transformers where we can “dial down” the output voltage to that ideal 110vac area.

The capacity (2KVA) is sized to handle a 516F2 power supply and 30L1 amp, and the build quality is solid enough to do shack duty with ease.

I bought these from an eBay seller, though the identical units were also available on Amazon, with the 16% Amazon cut added to them of course.

Each S-Line setup is getting its own unit.  The third is for other projects.

73

Steve
K9ZW

Tubes and Spare Tubes – Collins Edition

As my two Collins S-Line stations received tremendous amounts of TLC at the hands of Chuck W9KR, the vacuum tubes were checked with any out of specification replaced.

I am planning to buy at least one complete backup set as reserves.

Tubes are not “forever” items, and a ham would not even have a chance of a quick repair if you didn’t have spares on hand.

One of decisions is to what depth should I put in spares?  Would one comprehensive set between the two stations be sufficient?  Or one comeplete set PER station?  Or greater depth of all or perhaps just certain tubes?

Be careful about how your suppliers ship your tubes. One box ordered looked like it was place-kicked at the USPS perhaps in an afterhours soccer match! Amazingly the tubes all survived and tested okay.

I am looking for advice on storing spare tubes, especially as some become rather rare and expensive. Any time-proven methods?

73

Steve
K9ZW

Digging Deeper – Collins S-Line work after Mice Tried to Move In

Some more great work by Chuck W9KR, this time on my Washington Island Collins Station where during my absence from the Island during the CCP-19 Virus “lockdowns” a mouse family tried to build their new home in my KWM-2A Transceiver.

Lots of shells (and poo)

Well packed during their brief residency

I get mice into the radio shack area regularly, and have traps set.  But traps are useless if you are are not there to clear them out, meaning the mice were second or third wave while we were absent from the island for the extended period of the initial virus lockdowns.

While I captured the mice easily once we could tend our mousetraps, it wasn’t until last year that I realized they had taken up residence and created their own warehouse of food inside the Collins gear.

Collins Progress Update 1

Some in progress pictures as Chuck W9KR does his magic on the Collins 32S1/75S1 station.

Digging in at W9KR’s very well equipped workbench

Testing found some weak and failed tubes, all which are being replaced. I had bought tube kits for some of the units, and others have been sourced. All told about 8-10 tubes across the equipment are being replaced.

After a prolonged period of increasing voltages controlled by a variac, good meter readings

Prolonged means a lot longer than I would have thought, a gentle process.

Disposition of radios (2) – Collins S-Line Station

Collins S-Line (32/75/312-4…) Station Loaded for Service Work

Over the last 12 years I’d accumulated enough Collins S-Line equipment to not only complete the 32s/75s station started when George W9EVT gave me a 75S1 receiver with a shopping list of what I needed to complete an operating S-Line station, but a second KWM-2A transceiver based station which I will come back to in another post.

The 32S/75S setup was never fully setup once collected and consists of:

• 32S1 – transmitter
• 75S1 – receiver
• 30L1 – amplifier
• 312B4 – remote VFO
• 516F2 – power supply
• 312B3 – speaker
• DL-1 – dummy load
• Matching SWR Meter
• SM-1 – microphone
• SM-2 – microphone
• Voice processor
• Digital frequency Display
• necessary interconnect cables, manuals, some spare tubes, and so on

At no one time has the entire station been in operation.

I reached out via the reflector to fellow members of the Collins Collectors Association asking for help checking over the gear, and more importantly helping me with some issues with the other S-Line station (the one that I will come back to in a later post).

Chuck W9KR reached out to me, as we are just over an hour apart, offing to help me out.

So the station made it way to Chuck’s QTH for review, tune-up and any catch-up work/mods.

We opened up the 30L1 amp to test the tubes, as replacing these tubes has become rather pricy. W9KR has awesomely kept tube testers that outshine a typical museum piece which were put to duty testing the four tubes.

All of the power tubes tested great, and digging a bit further we discovered this particular 30L1 had already had a power supply upgrade board and kit installed.

We spent some time with my describing how I wanted to end up with a robust station that I and others who didn’t have much of a chance to operate tube radios could work with learning these skills.

The station was left with Chuck W9KR to be systematically gone through. Planes are to bring in the KWM-2A station from Washington Island so Chuck can help me sort that station out as well.

73

Steve
K9ZW