Category Archives: Repair

Hallicrafters S-38B

Finished the <a href=””>Hallicrafters S-38B</a>; it’s seen some daily use in my office at work. This is my first run-in with the AC-DC power issue and I found a way to route the power cord ‘HOT’ through the switch to eliminate (unless the house wiring at the socket is reversed) shocks from a faulty cabinet insulator.


I snagged three Astron power supplies recently from a listing on Craigslist. It was quite an inexpensive buy, but they were heavily abused and needed some repair, so overall, it won’t work out to a huge profit, but it gives me an opportunity to apply some skill and come out on top.

The previous user, I’m told, was a car-stereo seller and used the Astrons in a large display of car stereos.

From the group, there was a 35-amp RS-35A which, after testing, appeared to be in fine shape; only the fuse was out of order – the previous user had replaced the 8A ceramic fuse with a 10A glass, 3AG fuse – both incorrect and unsafe. The large value would allow more current to be drawn than what it was designed for; ceramic fuses are more resistant to breaking given the high current. Replaced the fuse, tested the supply for regulation under load and it’s now powering my FT-897D.

The two others, both RS-50A models were substantially abused and showed signs of having been run well over-current and for longer than the 50% duty-cycle.

But both still provided regulated voltage!

Both had incorrect fuses – replaced both with correct 10A, ceramic fuses. One had a 20A, 32V fuse (on the 120V primary!). Both had burned wires and the large filter caps (100,000uf in one and two 51,000uf in the other) were toasted.

Astron supplies replacement parts, so I’ve already repaired and tested the newer model with the single 100,000uf cap. Now waiting for two 64,000uf caps to repair the other. I had to make replacement 13.8-volt ‘common’ cables with black, 10ga wire. That ought-a hold ’em.

Heathkit HW-101 Refurb

How a Club Loaner Rig Becomes New Again.

This seemed like an extensive redo, but was not, because many of the boards went mostly untouched. It began with a redo of the HP-23 power supply with an HP-23RL board from The Heathkit Shop. And it ended with replacement of two of the Carrier Oscillator crystals, which with age had changed too much to adjust with serial or parallel capacitance.

For kits anyway, this was the pinnacle – the tip-top. No one would ever make a 20-vacuum tube transceiver again.

I purchased the rig and power supply for $75 from a W5FC
club sale of some old gear. The radio worked, having been gone through by the venerable OM, Don (W9VE).
However, a few issues cropped up, including an un-nulled carrier and a significant difference in
USB and LSB – USB is very muddy sounding and power output was low; LSB was completely normal and contacts
on 40m were made every time the rig was powered up!
In addition, CW output was almost nil with the CW filter in. Both the USB and CW issues pointed to the
center frequency of those two modes being outside the filter passband. Still, it was quite a buy, since
the HP-23B power supply can be found for well over $75 all the time on eBay.

The Old Front Panel was Dirty.
The front panel was dirty and worn from about 35 years of use and storage.
The new panel was found on eBay for about $11 and makes the old boatanchor look new.

The rig has stickers from the Heathkit factory where apparently it had been shipped to correct some
problems. These stickers date the rig’s assembly at before 1972. The rig works well with a Turner mic
(also from the same W5FC sale) and a later, fortunate fined was a brand new Electro-Voice 719 microphone
with the box, instructions, and (blank) registration card for $9.99 on eBay.

I chose to only do invisible or ‘functional’ mods which didn’t significantly alter the radio. But here are a list of Service Bulletins and the most popular (and necessary) Mods.

HP-23B Recap
Replaced most the electronic parts with the HP-23RL board from The Heathkit Shop.

Subsequently found an SB-600 speaker, with an additional HP-23A inside for cheap. This had been
originally built by WB8LOL – now K5LOL, Thomas, who’d built it originally built the unit in Detroit. He,
and the rig, found their way to Texas and via K5BJI (Mike Goidl), I obtained the supply.

Parts Sources

As a result of all the research, I’ve found some superb resources for part. Here are a few.

  • McMaster-Carr – superb online catalog and search tool
    • 9540K33 7/8″ x 5/8″ w/washers – feet for HD-10
    • 9540K56 25/32″ x 9/16″ w/washers – feet for HW-101 – fits #6 machine screw
  • Elliots Hardware – great stock of fasters (McMaster-Carr Numbers)
    • 90054A148 – #6 1/2″ Hex Washer sheet metal screw
    • 90054A146 – #6 3/8″ Hex Washer sheet metal screw
    • 90053A144 – #6 1/4″ Sheet Metal – for RF Cage
  • Ralphs Electronics
    • Amphenol 2-pin, Mic Plug –
    • Amphenol 2-pin, Panel Jack –
    • Type 86-3-24 – strain relief cover –
    • Type 86-CP11- 11-pin Plug –
    • Type 78-S11 – 11-pin Socket –
    • Panel Mount of 78-S11 requires –
    • Plain Cover –
  • Leeds Radio in New York.
    • (78-S11)
    • (86-CP11)

Current Status

There appear to always be a few items remaining to do, but the HW-101 operates properly now and
I’ve had two contacts so far: first on 20m (WA7ND) and the USB appears to work, but the Electro-Voice
mic connector shorted out temporarily ending that QSO. Secondly, on 80m with KC9MOS and the
ElectroVoice mic cord appeared to be working again for the duration. I’ll continue to be looking
for bad out-of-spec parts that might show up in performance, but the rig is working nicely!

Completed Appearance Improvements
  • Replaced the front panel with a fresh, clean one.
  • Replaced the rubber feet – McMaster-Carr 9540K56 is a perfect fit for the HW-101
  • Replaced some missing cabinet screws.
Completed Functional Mods and Improvements
  • Improved the power supply with a re-cap via the HP-23RL board, cleaning up some poor assembly and soldering.
  • Converted to handle Low-Z headphones – external speaker now mutes properly with “modern” 32-ohm headphones.
  • Improved the CW operation by increasing drive to the VOX relay
  • Killed most of the CW side-tone audio on key-up by dumping sidetone to ground.
  • Some mods had already been done, including the meter zeroing issue and some TX/RX improvements.
  • Replaced the poorly soldered Amphenol MIC jack.
  • Rebuilt the old power cord to supply 120V AC to the Power Switch on the HW-101
Final Completed Items – December 2008
  • Replace the USB and CW carrier oscillator crystals – bringing the CW and USB right back into IF passband, probably within 100hz or so.
  • Replace the old RCA RF Out jack with a BNC connector. The BNC is better than either the old RCA or a ‘UHF’ connector, plus the single-hole, bulkhead mount BNC didn’t require enlarging the hole.
  • Actually found a nearly broken output connection while replacing the RCA antenna connector – fixed.
  • Decided to not add a volume control to the side-tone. Maybe at a later date.
  • Replaced the grotty old 1/4 inch headphone jack.
  • Replace the Carrier Null pot with a new 200 ohm trimpot
Continuing Updates – May 2009
  • Swapped the 6EA8 Speech Amplifier (V1) with the 6GH8A which is a higher output version.

Tragedy Strikes!

My 25-year-old Weller WTCP gave out.

I was repairing one of the two Astron RS-50A power supplies I picked up recently and when I swapped the tips to get more heat out to the massive transformer center-tap… nothing. No clicking. The neon light was on, but no heat was home. It was a terrible discovery.

I’d had that old iron since Mostek. I think I bought it at some employee discount. Lots of projects from the old days and from recently were completed with that good ol’ tool.

So, my choices were to buy a replacement soldering pencil from Fry’s for $69.99, or just get a new one; the WES51 is not much more and is ESD and has a variable heat control. So I sprung for the new iron. But now: what to do – part out my old friend? Can’t let that 2A transformer go to waste. But I can’t hack apart an old friend. Aw, heck, went right back to Fry’s and snagged a TC-201A pencil to go with it. Now it’s the garage soldering iron. I think we have soldering covered here at the house.

A $10 Scope

My B+K 1435 Oscilloscope went down over Thanksgiving weekend. Really, it went down – it fell against my chair (I shouldn’t keep it propped up like that, I guess). However – the “A” channel input went bad. I took it all apart – screws everywhere on the carpet.

I was so close to parting it out then W5AAN (Ginger) urged me to keep trying on fixing it. Turns out these old scopes are old-school. The traces are nice & wide and the parts aren’t surface mount (SMT). I wound up fixing a total of three problems with it.

The pot for the “A” channel vertical positioning had two broken traces right near the pot. I was able to easily scrape and short ’em with a bit of component lead wire. Soldered those on and it worked just great.

Got it all back together and found that now the “B” channel didn’t work. Well by this time, I know where everything is – opened it back up and the lead to the center conductor on the BNC connector had broken. Soldered THAT back into place and now the scope works great.

It works so well I’m considering buying some new Gel batteries for it – it’s a portable model and while it was all apart, I tested the charge circuit to be working.

Perseverance. My $10 scope soldiers on…