It's not often that I find a piece of Heathkit gear in such pristine condition. I picked up this transistor tester from a friend, and it was CLEAN! I replaced the batteries, cleaned and lubricated the switches and controls, checked calibration, and it was ready to go to work. Here's a few pics...
Wow, this attenuator is back on the walk of shame. I've beat this thing relentlessly for years, but occasionally I'll set my workbench switch to the wrong position and light it up :-) . We'll, I did it again, a Heathkit SB-200 amp smacked right into the 1st 20dB pad and let the magic smoke out. She's repaired and back on the front lines. Here's a few pics....
This Heathkit amp had a few problems... it was running very hot at idle, it stopped passing RF on TX, and had a soft key that was getting rf into it and causing erratic operation. Here's what I found...
This is the 6 meter (50mHz) transverter that matches the Yaesu FT-101/B/E/EE/F etc lineage. I got this to match up with my FT-101E station. It had not been on the air in many, many years, but turned out to be a fairly easy resto. Here's a few pics...
Well, the IC-211 is back on my work bench. This time, the VFO fail and is stuck on the "power up" frequency. It has become increasingly sensitive to dust on the LED sources and optical receivers in the last year or two, perhaps the output of the LED sources is diminished a bit. I discovered alignment to be at fault as well. Check the videos...
It' back up and running fine. I operate it at about 1 watt out, into an old Vocom brick, for about 20watts to the feedline. With the feedline loss and antenna gain, my erp is around 395 watts. The pic below shows signals received today, so it's rx sensitivity is pretty good. Below that, you'll see my old Vocom amp, and lastly, a recent log snapshot. I just works my best 2m ft8 distance from NC, a bit over 1300 miles on a recent e-skip opening. Despite this gear being almost 50 years old, it's still making great contacts.
To preface this, this project spans a bit of time, so the videos might seem a little disconnected...
This is an Elkin 8-Tube mono-band amp, originally built in Elkin NC in the late 60's. It uses a link coupled input and output, is grid driven, and is biased in AB to AB2 territory. The tube complement is 8ea 1625 JAN surplus tubes from the late 1940's, and a pair of 0A2 cold-cathode, gas-discharge tubes for screen regulation. Bias regulation is via a series stack of zener diodes. Elkin amplifiers are extremely spectrally clean when properly set up. I think the cabinets were made by Hammond, but I'm not 100% sure on that. I was fortunate to have met and known Ray (the designer / builder), beginning sometime around 1974 and a few times over the following years.
Being grid driven, these require very low drive. I set this unit up on 29.000 mhz, though I've put these on 40 and 20 meters in previous years with a simple addition of inductance to the ends of the link coupling hi-z windings. The smaller, mobile versions (same design) had switchable tanks for 10, 15, and 20m.
A friend picked this up in a batch of gear in a purchase, and it needed some attention. Another friend recapped the amp and got it running for him, and I took the challenge of bringing it to peak power. Part way through the project, the owner did some major cleaning and cosmetic work, and I then resumed the repairs and updates.
The Elkin design morphed and improved over the years, partially due to design updates, and partially due to various parts availability to the designer/builder. This particular early version had lower plate transformer HV (around 700vac), though the screen in all of this ilk was regulated at 300vdc and the HV derived bias was around -70vdc fixed. Later models had an adjustable bias supply, HV transformer output of over 850vac, an adjustable solid state screen voltage regulator, etc. As a result, these early models typically topped out around 400 watts output when at saturation. They were like the Alpha Amp adds back in the past...they could take a brick on the key all day, effortlessly. Let's get started on this 55+ year old girl...
The power cord needed replacement due to some cuts or possibly doggie chew damage.
I subbed in some bias and screen voltages to test the amp at the correct voltages...
This 47 ohm resistor in the bias distribution had shot up to several hundred ohms and needed replacement.
