Thursday, August 28, 2025

Swan 350 #2

 This is another Swan 350 I got from an estate. Built around 1968, and surprisingly enough, it worked! I gave it s good cleaning, painted the cover, replaced a few caps, serviced the controls, etc. Someone added a sidebar reversal switch, but otherwise, it's pretty much original. I didn't document this one very good, but here's a few pics...
















Tuesday, August 19, 2025

4-Tube Elkin Repairs

 This is a 4-Tube Elkin amp a friend picked up at a hamfest. It was in need of a bit of repairs and some updates. The Elkin amps are grid driven, link coupled, push-pull Class Ab2 designs. Very clean spectrally, well made, and were regionally popular on CB in the 60's through the 80's. It was named for the town in was built in, Elkin NC. 

Some of the later mobile models were band switched for 40 through 10m, and the tank in input circuits of the fixed station amps were tapped. I ran a 12-tube version on 40m for many years, with 0 problems. 

Here's a batch of pics, some vids, and descriptions:



A few pics above of the finished amp...





An initial look under the chassis shows a bit of a mess...

The negative voltage pass transistor is literally bridged B to C... smh...

An attempt at screen regulation was also all fubar...

Another transistor was bolted in, collector grounded, and nothing else.

Incorrect tubes installed... One had literally melted the glass and started to implode.

Correct tubes installed, note size difference with the small tubes that it came in with...

Bleeder resistors incorrectly wired, and some were bad.

Filter caps were shot...

Keying circuit for contact closure output was incorrectly wired and kinda hanging in the wind...

Delay cap blown open...

2 Plate caps were broken free of the aluminum tank coil. That stuff has to be soldered with a combination aluminum rod. 

New filter caps in...



New bias regulators installed and wired correctly...




Replacing bias caps...

Plate choke replaced...



Split Plate tune cap needs padding...

Spot drilled and smoothed for variable 150v screen supply...

Dual Filament switch installed to enable use of 6v or 12v tubes...

Variable screen supply installed...

Split input coil adjust and sealed...

Split plate tune cap padded properly...


A number of new parts installed :-)

Swan 500C Restoration

 This is an old Swan from a local SK's estate. It had been out of service since it died in 1998 (according to notes inside the cabinet). It was pretty grungy. I gave it a good cleaning, serviced all of the controls and switches, recapped it, changed a handful of out of spec resistors, replaced the RF choke in the PA, and replaced one of the shorted tubes in the PA. The cases got a new coat of paint, too. She's back up and running, and looking good! Here's a few pics...