Manager


Manager - NA4M
Manager Notes

Reviews For: BC-348 WWII MW/SW Receiver

Category: Receivers: non-amateur adaptable for ham use

eMail Subscription

Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted.
Review Summary For : BC-348 WWII MW/SW Receiver
Reviews: 8MSRP: 348
Description:
Businesslike wartime reciever used in planes and on the ground, recieves most
of the MW and SW bands in switchable ranges, has a BFO for CW work and an
xtal filter that's very nice for CW and even listening to AM SW broadcasts.
Product is not in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0083.8
K3HVG Rating: 2022-01-25
Very nice usable and collectable military radio Time Owned: more than 12 months.
After some 80+ years, the BC-348's are still on the air in numerous locations. They can be made to function with minimal work, with the proper documentation. The late WWII J, N, and Q models are the cost-cutting versions, identifiable by the lack of antenna trimmer control. The J, N, and Q models use single-ended tubes. The selectivity issue can be easily fixed via use of either a BC-453 or Navy ARC-5/R-23 low-frequency receivers, loose coupled to the BC-348's IF strip. By now, each and every BC-348 should have been fully re-capped and resistors checked. Once done, they are good for another 30-40 years! I use them with the ART-13 transmitters, here. No issues in crowded conditions.
N8FVJ Rating: 2021-04-03
Fine AM Broadcast Receiver Time Owned: 3 to 6 months.
The BC-348 was my first SWL receiver in 1965. I recently acquired another BC348R.

The new to me BC-348R has a new custom CNC machined front panel, S meter and an AC power supply installed by the previous owner. The inside appears like new.

I replaced all paper and paper oil capacitors. Interesting that the original were still in good condition without excessive leakage.

The existing AC power supply had a SS bridge rectifier, 1HY choke and a dual section 50uF can type capacitor for a CLC filter. It also used a 500 ohm resistor on the output to drop voltage to 230 volts DC. The design produces low level hum due to poor filtering.

I replaced the 1N4007 rectifiers with low noise UF4007. The filter cap was replaced with a JJ dual 100uF can cap rated at 500 volts. The 500 ohm resistor was removed and the choke was replaced with a Hammond 30HY @ 40ma choke with a DCR of 595 ohms. The new power supply produces 235 volts @ .06mv ripple and the receiver is hum free.

Next was an alignment. Although not far off alignment, it is critical that an alignment is performed with the crystal filter in circuit. Once completed, the receiver only drops about 1 S unit with the crystal filter in line.

These BC-348 were built to use a 1-5 ohm antenna. The antenna trimmer capacitor in the BC-348R series is vague in operation (no sharp peak). I installed a 9 to 1 unun at the antenna input. Sensitivity went up and the variable antenna capacitor has a sharp tuning peak at about 50% value at all frequencies.

Further performance can be obtained replacing the 6K7s with 6S7 tubes. The dual RF front end will require a slight peaking of the trimmer capacitors to realize the slightly lower noise floor and hotter front-end with the 6S7 tubes. The IF section does not require any tweaking after changing from the 6K7 to 6S7.

One reviewer mentioned receiver is rated a three (3). The rebuilt receiver hears about 95+% of a Collins R-388 on 75 meter AM phone. It also out hears any of the Hallicrafters S series of receivers (possible S-71 exception) and it should due to it has a dual RF front-end and a blocking Dynamic Range of 87. I doubt the Hallicrafters S series of receivers rate a DR of 60. The BC-348 is at least a 4.8 rated receiver.

Per another site, the BC-348R receiver was measured at a MDS of -137, 20kHz Blocking range at 106dB and a two tone Dynamic Range (20kHz) at 87dB. For a 'boat anchor' receiver designed in 1936, this is good performance. Definitely not a Collins R-390, but quite acceptable for SWL service and Ham 75/40 meter AM.

Note- this review is 5 years old, but an update changed date to 2021.

KM1H Rating: 2019-11-03
More nostalgia and military set collector hype than performance Time Owned: more than 12 months.
Back in the 50's when they were very common at surplus stores (Almost none of those remain) they were a cheap entry level set for the new ham or others on a tight budget. Most were missing the dynamotor, the original optional AC supply very scarce, so a homebrew supply had to be built. Most of the ones Ive worked on were real hack jobs.

There were several models and manufacturers and not all have held up well over the years as paper caps in sealed cans are still paper caps and should be replaced if original performance is the object. Same with many carbon resistors.

Thousands were left behind in Europe and Pacific nations after WW2 was over and since they were far better than pre war local production they became highly desirable. Today it is often nostalgia IMO.

They tune only up to 20M or 17M at a stretch but performance is way down on 17. The crystal filter is at 915 kc and marginal on CW but better than nothing.

Performance on 80/40/30 CW is decent but not up to most mid range ham receivers of the 50's which can often be found at less cost than a 348 which has reached collector status . On 20 the tuning rate is poor and sensitivity down as expected with the late 1930's tubes used.

In 1955-56 I operated a couple at other homes which convinced me to buy a good used Hammarlund HQ-129X which Ive never regretted and have another these days. They, a HQ-140X, NC-173, NC-240D, SX-25, SX-71, plus a few others are often less cost than a 348, do more, and work better.

Carl
IZ2EAS Rating: 2018-05-12
My first "real" short wave radio Time Owned: more than 12 months.
I was a teenager in 1980 when, after having spent two years listening to the short waves using a domestic 5-tubes receiver, I decided it was time to make the big jump and get my first “real” receiver!

With the constancy of the drop of water that digs the rock, I convinced a friend of mine (who was a SWL too) to sell me his BC348R; he had a brand new Grundig Satellit 2100, so he did not need that old, bulky, heavy metal box any longer (well, that was my point).

Guys, that was a dream come true ! A real receiver, at last. The receiver had been modified by its first owner: he introduced – in place of the dynamotor - a small board with the second conversion (915 kHz to 85 kHz) – made using only tubes. An absolutely well done job, which increased the total number of tubes to 11, guaranteeing very high sensitivity and selectivity! He added also a nice looking S-meter. The power supply and the audio amplifier (which also used tubes) were built in an separate box.

I spent countless hours in front of my BC348R; at that time the tropical bands – my favorite hunting ground – were very active, with stations from Asia appearing in the afternoon, followed by Africa in the evening and then – in the deep of the night/early morning – by stations from Central and South America. Sure it was hard to get a QSL card or a confirmation letter from them, but it was good fun nevertheless.

The BC348R performed flawlessly; the “black beauties” of death (the black/brown capacitors that tended to leak) had been replaced by the first owner, I replaced a power resistor in the second conversion once, but never had to replace a single tube despite the heavy usage.

Needless to say, I never wanted to part from it; when I relocated from my home town to Milano, it followed me. My SWL friend - who I think soon repented of having sold it to me - tried repeatedly to buy it back, without success. And even if now I use SDRs and modern equipment for the “serious” job, the BC348R has been the first radio to enter my shack, and it will be the last to leave it !

KZ4B Rating: 2016-03-15
One of the very best pre-WW 2 Receivers ever! Time Owned: more than 12 months.
About thirty years ago, I stumbled on a mint, un-modified BC-348R for only $85.00 because no one else at the little Greenville, S.C. Ham-fest was interested in buying it. As a Novice and early General Class Ham (circa 1959), I had struggled with a Hallicrafters S-53A and would have given my "eye-teeth" for a BC-348 (or similar receiver) if I could have found one at an affordable price.

With some difficulty I was able to locate an original B-17 shock-mount with "stock" power connector (from an aircraft "bone-yard" in an Arizona desert). This aircraft mount was essential to allow use of the "stock" power connector as it plugs into the BOTTOM of the receiver.

Wanting to keep the BC-348 receiver completely original to the degree possible--I home-brewed a 28 Volts Alternating Current (at nominal 8 Amps max.) to replace the original 28 VDC aircraft power supply. This allows powering the receiver's 28 Volt (indirectly-heated--so no ac hum) filaments at roughly 4 Amps without re-wiring for 6 or 12 VAC as is commonly done. In addition, roughly 4 Amps is available via a small (100+ VA) 28 VAC to 120 VAC "control power" transformer with silicon diode voltage doubler/filter for the receiver's B+/Plate Voltage. The 100 VA+ Control Power Transformer (wired backwards to step the voltage UP) is mounted along with rectifier/filter components on the "stripped down" original (28 VDC Input/Hi-Voltage DC Output) Dynamotor Base which plugs into the INTERIOR of receiver.

My BC-348R was marked at the Audio Output Jack "Wired for 600 Ohms". I therefore located an original "LS" Series Aircraft Loudspeaker (With built-in 600/3.2 Ohm (Impedance Transformer) and mil-spec. 600 Ohm Earphones. I have also located an LC Type Narrow 600 Ohm Input/Output Audio CW Filter that was supplied on many aircraft to supplement the BC-348's Crystal IF Filter.

A JAN (Joint Army/Navy) design policy required that all "tactical" super-heterodyne receivers have two (RF) radio frequency amplifier stages--not because the extra amplification/gain was needed--but because the extra RF Filtering was needed to prevent "Local Oscillator Leakage" which could allow Enemy Radio Direction Finders to detect the presence of potentially hostile radio receivers. While enemy detection is not a concern today, improved "Image Rejection" associated with two RF Amplifiers and somewhat analogous to modern "Multi-conversion" and narrow crystal/mechanical "Roofing Filter" designs is beneficial in today's operating environment.

Do Not Re-Cap these receivers unless a genuinely faulty component is found as the normally leaky foil/paper capacitors are individually packaged in metal oil-filed enclosures--so they tend to last indefinitely. The plastic-encased mica capacitors (as I have personally found) are less reliable--but I still wouldn't replace them unless found to be individually bad.

This 1936 vintage RCA-designed receiver is reliable, stable, compact, light weight, mechanically well-engineered, and absolutely state-of-the-art for it's time. The BC-348 Receiver coupled with the Collins-designed ATC/ART13 Transmitter as employed in the magnificent B-29 Bomber were so advanced that the USSR copied both for service in tactical and other aircraft well into the early 1980's! Don't take my word for it--the Russians knew a good thing when they copied the BC-348 virtually nut-for nut and bolt-for bolt. They even standardized on our vacuum tubes and other internal components to the degree that they are directly interchangeable with our (USA) communications gear. Nuff Said!
K5UOS Rating: 2012-06-01
Great for a 70 year old receiver Time Owned: 0 to 3 months.
I finished restoring to BC-348-Q models in May of 2012. Both we purchased on EBAY for approx. $100 each. The 2nd was going to be for parts but was repairable.

The first RX had a partial conversion that was never completed. The PS was poorly designed but there was no additional modifications. I purchased a suitable Hammond transformer and choke and built a +220VDC power supply using a 5Y3 rectifier. I found many sources of information on the net including some by Pete, AC7ZL.

I traced all the wiring expecting errors but all harnesses were stock and the only changes were associated with the PS connections. The terminal strip from the original RX was gone and I built a new one using a piece of fiberglass and solder lugs. I used the AVC/MVC switch for on-off. The original Jackson like PL-P103 plug had been partially dismantled to use two pins for AC plug. I removed the rest of the PL-P103 innards and mounted a 3 prong socket in the remaining frame. I also removed the large filter capacitor.

I checked all the resistors and capacitors and all were within tolerance. After converting the botched PS conversion I tested the PS and finding no issues installed the tubes. The receiver powered up and received well on all bands. I did a quick realignment of the IF using 915MHz. The receiver was out of alignment for 915MHz but I doubt it had been adjusted to the crystal band pass.
I also changed the low Z audio out to the high Z to match my LS-3 speaker. The alignment and the speaker matching was a marked improvement.

The PS - I used choke input and increased the filter cap to 60uF. I also included a 1000uF/63VDC cap with negative lead to the floating B- and positive lead to ground. The result is an almost hum free audio.

I learned that CW/SSB was not possible with the RX in the AVC setting. I use MVC setting which gives surprisingly good audio on SSB. The crystal filter and IF are not quite aligned which I will fix on an upcoming weekend. The IF and filter in the 2nd receiver are better aligned and there is a slightly better filter response in the 2nd rig.

I had issues with the anti-backlash gears and tuning which was cured with a slight shift in the large tuning capacitor. There is a QST article describing the 30 second fix. The tuning is now amazingly smooth.

The 2nd rig was not modified much more than the 1st. But some fool broke up the beautiful wire harness for some dumb reason. I had to install another power supply including a fuse and do some rewiring. I still have to go in replace some ugly cloth wire which, if you know the tech manual and the beautiful way the rig wiring is color coded, just does not match the original design. I did my resistance and capacitor check and was amazed that the components were also within tolerance. After replacing on tube the receiver operated almost perfect on all bands. I had to clean the BFO switch. Though I have the 2nd rig electrically checked and running really well, I have not checked the alignment yet but have been working on the cosmetics of the panels and cabinets.

I bought the rigs because my dad, W1KPS(SK) had several surplus military receivers back in the 50’s and 60’s. One was a BC-342 and at least one other a BC- 348. These are 100% fun to restore. Pete and many others have a lot of useful information for restoration of the BC-348 on the web. There are numerous QST and CQ articles or modification manuals to help. Off course the original receiver manuals are so awesomely detailed you will learn all about your receiver in short order.

If you are deciding to purchase BC-348 to restore and have a basic understanding of receivers I think you will be very happy. It is certainly not a SOTA receiver but the look, the feel and amazing quality of this 70 year old receiver will be lots of fun.

73, Don K5UOS
SWL377 Rating: 2006-08-21
Great history, OK performance Time Owned: more than 12 months.
I like to imagine that my BC 348 flew in a B 17G over Germany in WW II, but I have no proof that it actually served in combat. Mine has a postwar civilian AC PS sited in an external speaker cabinet and an outboard audio amp to give loudspeaker volume. The original dynamotor was removed. I found dial accuracy to be outstanding on all bands. HF sensitivity is OK, not as good as my Hammarlund HQ 180 but good enough for normal listening. It is also a noisier rcvr than my Hammarlund. Stability my my BC 348 is good enough for decent SSB copy without frequent retuning even on 20 meters. I use the BFO for SSB demod and it works fine. I listen to HF USB marine comms in the 8 MHz band with the BC 348 and it does just fine once it has warmed up and stabilized. Sensitivity on LF is decent, I could hears some distant NDBs that are hard to hear in my area. On my set the XTAL FLTR acts only as a high low sensitivity switch and accomplishes nothing useful in narrowing bandwidth and maintaining decent sensitivity in the center of the filter response curve. Maybe it needs work but I cannot find any bad components in that section. I love having a rcvr with such a rich heritage, but I wouldn't depend on it for any serious DXing when I have my HQ 180 at hand. To be fair, it was designed much earlier and withstood a lot of abuse. My BC 348 hasn't had any mods other than the PS and 99% of the caps and resistors are orginal. I love the looks of the set, especially the Art Deco bezel over the main tuning dial. It is pretty amazing that it can deliver the goods over 60 years after it left the production line. I wish it covered BCB. If it did I'd put it in the living room. The BC 348 has looks good enough for a family room while the better performing surplus aircraft HF rcvrs (like my ARR 15)look like they belong in a ham shack or military airplane. BC 348s are still plentiful and not horribly expensive ($60-$150 at most swaps depending on cndx). I suggest buying one while they are still affordable. As a side note, I once saw a 100% solid state BC 348 owned by the late Command Set collector, Henry Engstrom. It looked VERY professional inside, with fiberglass PC boards etc. It didnt work and Henry had no documents on the conversion. I often wonder who has it now and if they restored it to operation.
AC7ZL Rating: 2006-07-31
Fun to play with Time Owned: 3 to 6 months.
A while back I was fortunate to stumble across a BC-348-Q at a hamfest. I am partial to vintage electronics and boatanchors, and the BC-348-Q has a certain aesthetic charm to it---maybe it's the "military" look, the illuminated, shuttered dial face, or the tuner crank that requires nearly 100 turns from lock to lock! Whatever the reason, I purchased the radio and took it home.

I'm no old timer, but from what I gather, the BC-348 series of radios enjoyed some popularity as convert-to-ham-use surplus following WWII. For this reason, finding an unmodified BC-348 is somewhat difficult. The radio was originally designed to be powered from a 28 volt DC supply. An internal dynamotor produced the 220 volts for the radio's plates. For these reasons, at the very lease, most BC-348's have been rewired for a 6 volt filament string, and often contain homebrew power supplies mounted in the dynamotor bay.

My own radio contained wiring errors, a bad tube, several weak tubes, and a full set of dried out capacitors. I also found several fractured carbon resistors which lead me to repopulate the entire chassis with new caps and resistors. My radio came with neither a dynamotor nor power supply, so I built and installed my own supply.

Repairing equipment like this is made much easier with proper documentation. Schematics are available at the BAMA site, but the best scans I found were available at www.jamminpower.com/main/bc348.jsp .Note that there are several siblings in the BC-348 family, denoted by a letter extension. In my case, the radio is a BC-348-Q, originally built under contract by Wells Gardner. The revision letter is important, because there can be significant wiring differences from one radio to the next.

The radio offers 6 bands of coverage, from 200 khz to about 18 mhz. The AM broadcast band, unfortunately, is omitted. This probably has to do with the fact that the set uses a 915khz IF. The dial features a shutter mechanism that selectively occludes the tuning dial during band changes, such that only the frequencies associated with the selected band are visible. Mechanically, tuning is very precise. A worm gear drives a zero-backlash gear-train with such reduction that the dial crank has to be turned nearly a hundred times to get from one end of the tuning scale to the other. In addition, the set features an adjustable BFO and crystal filter for CW work.

While the set has great character and I do not for a second regret any effort that went into restoring it to operation, its use as an everyday ham receiver is questionable. Sensitivity seems good. Selectivity is not all that great (though I've been told that this may be due to leaky caps in the IF cans.) Even if it was better, the resolution of the dial markings are such that, at best, you will never know more than your approximate frequency.

Tracking on my set leaves much to be desired. The low band tracks fairly well, but the other bands do not. Without going into excessive detail, alignment adjustments are fairly limited, which leads me to postulate that some of the caps inside of the rf compartments may have drifted. Digging that far into the radio is doable, but something of a mechanical nightmare, and something that I will likely avoid for now.

Some writers have complained about the amount of volume that the radio's audio amp (6K6) will produce. In fact, one of the common radio modifications found is the insertion of additional amplifier stages. This criticism is not entirely fair, in my opinion. A headset of proper impedance will produce more than enough volume for ear damage. If you want to drive a speaker, make sure to use a matching transformer, and if that's not good enough, add a stage of outboard amplification.

The crystal filter, by the way, has significant attentuation when it's switched in. One trick that I discovered to improve the radio's performance was to measure the actual resonant frequency of the filter crystal, then align the IF cans in the set to the measured frequency. For example, my crystal resonated at 914 khz, so I aligned the IF path to 914 khz. The radio works fine and the filter works much better.

For day-to-day useability, selectivity, dial resolution, and features I'd rate this set a 3. On the other hand, a fellow ham noted that the BC-348 was not designed for stellar performance. Rather, it was designed to "...work ok while you were being shot at." It certainly does. Moreover, for charm, charisma, and historical appeal, the radio scores a 5. It is easy to troubleshoot and repair, and it is my expectation that this 60-year-old radio will still be functional in another 60 years. Therefore my composite score is a 4.
Pete, AC7ZL
www.hpfriedrichs.com