Ham Radio


Hallicrafters SX-28A

I just acquired a nice Hallicrafters SX-28A. I picked this one up because I had an SX-28 some years ago and it ended up “displaced” when I loaned it to someone who didn’t have the courtesy to hang onto it.

This radio is in pretty good condition but does need some cleaning and minor restoration. I haven’t powered it up yet, but I suspect it will also need some of the capacitors replaced.

One thing I will likely need is a band-switch knob, which is slightly cracked and the sides are angled forward. It also needs a bottom panel to the case that’s missing, but I should be able to fabricate that.

Unfortunately, I don’t have enough time to do a full restoration of this radio, which is really what I’d like. If you know of anyone in the Midwest that does this kind of work and is familiar with the SX-28A, please let me know. Otherwise, I might be inclined to ship it a bit farther if needed.

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Russian R-158

Here is a recently acquired Russian R-158. It’s a 30 to 80 MHz FM (5 KHz deviation) radio with 25 KHz steps. It seems to work just fine and is apparently in pretty good condition. From what I understand, these were used in the field by the Russians in their war with Afghanistan.

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SEM-52S German Radio

A recent addition to my collection is this German SEM-52S VHF FM radio. It’s a 1980s/1990s synthesized 6 channel squad radio that covers 46 to 58 MHz in 25 KHz steps and produces 1W.

Harder to obtain than it’s SEM-52A predecessor, the improvements the “S” offered were field selectable frequencies for the 6 preset channels using a set of rotary switches just under one of the covers, and the ability to run off of 8 AA batteries.

This one’s in pretty good condition, although the plastic battery case insert that holds the AA batteries did have some damage from leaky batteries that caused most of the metal battery contacts to fall off. No problem, I simply wired in a set of 8 AA rechargeable batteries into the plastic insert and it was off and running.

I have it setup for 51 MHz, which is the common cold-war radio collectors frequency and 52.525 MHz, the standard 6 Meter calling frequency, along with a couple more 6 Meter simpex channels and 2 common military frequencies. The first contact on it with W8NSA about 10 miles away went fine. I did have to adjust the reference frequency trim a bit to get it right on frequency, but nothing else other than the battery pack needed attention.

It appears that I need to loose a few pounds before I can clip the chest strap on the case without cutting off circulation. I believe, however, that I’m really going to like this radio.

I am still looking for any operator or service manuals for this radio in any language — electronic or printed. If you can help, please contact me.

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H-250 to SEM-52S

For those interested in the SEM-52S, I just received an NF-7 connector for it and added an H-250 handset to it. It took me a bit to figure out how to connect it up as I found some of the information on-line confusing. So, here’s what I have that works fine.

NF-7  Use       H-250 Color
A     Speaker+  White 
  (1K chip resistor between A & B)
B     Speaker-  Black
C     Mic+      Red
D     PTT       Green
E     ?
F     8V
G     Ground    Mic Shield

I believe the colors are pretty standard for the H-250 handsets, but I suggest checking first if you’re going to do this.

Also note the 1K chip resistor I put across A and B on the NF-7 connector for the SEM-52S (right side in picture). This seems to be necessary to get the audio to switch to the headset. Apparently the .9K or so resistance of the handset didn’t do it.

If you have any more information on the handset connector for the SEM-52S and how the various connections really should be used, please pass it on to me by E-Mail (cscott@n8dnx.org) or on the “armyradios” Yahoo Group. If you have an original equipment handset for an SEM-52S for sale (very good condition only), contact me!

D-104 From My Youth

Here’s one of my favorite radio related items. It’s the classic Astatic D-104 microphone I bought when I was a kid. In fact, I remember having my mother drive me to the store to pick this up because I couldn’t drive yet. That makes this microphone nearly 50 years old, which gives you some insight into how old I am.

I haven’t used it for some time because this D-104 has it’s original crystal element and I never did install a buffer amp in it to make it compatible with modern transceivers. That was until recently when I happen to run into an unused buffer amp board made specifically for this type of microphone at the Traverse City swap. This past weekend I installed the buffer amp and fired it up. My first contact with it in years was breaking into a pile-up for a special event station in Sweden on my first try (at 100W, so I was happy).

Not only is this microphone still in perfect condition, but the red felt covers are the ones I made for it the very night I bought it. Needless to say, it has special status in my “Shack”.

My Pair of Perfect PRC-6 Portables
Now Available

These are PRC-6 "Banana" radios built originally in the 1950’s. The two I have were remanufactured in 1968 and have been in the boxes since then. The picture shows one with one of the NOS (new old stock) H33 handsets that were typically used with these radios. As you can tell, these radios are pristine. I have the two radios including original boxes, crystals, antennas, handsets, test sets, manuals, inverter power supplies (internal) and batteries.

The PRC-6, originally introduced around 1952 is a 47 to 55 MHz crystal controlled FM "hand held" radio that was used mostly for short-haul (<1 Mile) communications in the field. The ones I have use tubes and the various voltages those required. later variants were multi-channel and some solid-state. This model, though, is the classic Banana radio.

I’ve tested both of these radios and aligned them to spec. They both sound very good, other than the bit of whine in there from using the inverter supplies rather than just batteries. They both put out about 350 mW, which is just above spec and receive on both of them is well below 1 uV.

I would sell these, but only together as a pair and with all of the associated materials. I will not sell them to someone who’s going to beat them up in military field simulations or who will separate the two from each other. Expect to hand over close to a kilo-buck to get the pair–I am not motivated to sell them. You will have to convince me that you deserve to have them and that you will properly care for them.

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MEL PRC-2000

This is a PRC-2000 made by MEL in England that covers 1.6-30 MHz. I love this radio. It’s relatively heavy for a "manpack" unit, but operationally it’s a dream. This radio is what’s called a "TRF" (Tuned Radio Frequency) receiver. That means it has no IF and does no receive mixing. All the receiver stages down to the detector operate at the RX frequency. This makes it a rather unusual design, but seems to give this radio some excellent characteristics.

Not being able to get a remote control handset for this radio, I modified a standard Klansman handset with a 10 position thumb wheel switch for selection of the 10 memories from the handset. A quick project, but a major addition to use of the radio.

With the 10 AH battery pack I built for this radio, it can run all day and even more if I don’t do much transmitting. This pack is an earlier one I built, but it clearly shows how well a 13 cell pack fits this radio. It’s 13 cells because the radio is nominal 15V and doesn’t like running down below 13V.

No, this radio is not for sale (unless you REALLY, REALLY want it).

Heights Aluminum Tower

Someone asked me to provide them with old Heights Tower documentation, so I thought I’d post it here.

Thought I’d also post a picture of my tower and some of the antennas. It’s not as high as I’d like it to be, but I have lot limitations that keep me from going higher.

This is a Heights aluminum tower with (from the bottom up) a single 6M element, scanner beam and 220 Mhz beam on left side mount with a discone on the top, another discone on the next side-mount, an inverted V (currently a BWD-90), Mosley PRO-67B beam, small UHF beam (barely visible), pair each of 2M and UHF circular polarized beams with elevation rotor, and on the top a Diamond X500 vertical.

It all works pretty well, but I still need a few more antennas. I do usually have an HF vertical at the back of the yard but need to replace the cable going out there that was cut when the sprinkler system was installed. There’s some things that need a bit of minor maintenance now, but since I last put this up (it’s on a motorized hinge base), one tree has grown to the point that I will have to sacrifice the X500 to bring the tower down. Such is life!

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Heights Tower Docs