Wartime Civilian Radio LW conversion

[coopzone]

Hello,

Does anyone have details of the simpler long wave conversion. I believe consisting of a couple of extra coils and a switch on the rear of the radio?

Ideally has anyone reverse engineered this mod and has the circuit?

I have the "Bush" conversion details from the cd-rom (Above) but was hoping for a simple version to try.

Thanks

Derek

[G6Tanuki]

I vaguely recall that some LW conversions simply added a pair of large-value preset mica trimmers across the standard MW coils.

There was, after all, only 200KHz carrying LW content-of-interest to UK residents so it was easy to peak things up for this, and the signal strength on 200KHz was generally high enough that issues of optimising L/C ratios were irrelevant.

[David G4EBT]

Can't help with the circuitry, but they often fall victim to conversion to Bluetooth, with the original on-off switch on the rear used to operate the Bluetooth device. I guess that if you convert yours to Long Wave, you could replace the original unswitched volume control with a switched one, and use the original on/off toggle switch on the rear as the LW switch. I'm surprised that more haven't been converted either by enthusiasts over the years, or by original owners back in the mid 1940s.

The one at this youtube link appears to have had a Long Wave conversion as a valve radio, with an additional knob on the front panel. It's not in very good shape (delaminated plywood on top panel and the knobs and speaker fabric aren't original). Ironically, it may in fact still work as a valve radio, but they fetch far more if converted to Bluetooth. (typically £200).

https://www.youtube.com/watch?v=Xop5d8XvbLA

(You'll hear inaccuracies in the dialogue on youtube, but that's not a topic for discussion, has no relevance to this thread and doesn't help Derek in his quest for LW info).

[coopzone]

That would do if anyone has details?

I came across this idea on a transistor radio - as you say it just had a switch for radio 4 and no tuning as such.

Derek

[Ed_Dinning]

Hi, from memory of one of Chas Milers publications, I seem to think a pair of wearite P coils were used with a simple switch on the rear of the chassis, maybe even fixed trimmers to give LW Light only?

Ed

[Mike. Watterson]

Yet a decent bluetooth adaptor is about £6, and inferior to direct 3.5mm cable, or even the £2 USB to Audio with a £2 USB adaptor for phones/tablets with no headphone socket.
A switched socket across the volume control.

Is the BT conversion phenomenon because almost every "BT speaker" sold today is garbage, having a 2" to 3" speaker driven by a headphone amp in bridge mode?

[Station X]

I deconverted mine as I didn't like the switch disfiguring the back panel.

I may still have the coils somewhere and will look for them if someone can post a pic of what they look like.

[coopzone]

Hi station X,

I can't find any pictures of what they look like - but hopefully someone will have one.

Thanks for looking.

Derek

[Graham G3ZVT]

Originally Posted by coopzone

I came across this idea on a transistor radio - as you say it just had a switch for radio 4 and no tuning as such.

My very first post to the forum was about such a set. An Emerson Vanguard 888 made for the UK market.

[Glowing Bits!]

Mine has a LW converer half way up the back panel, it looks primitive but sort of works (in a fashion).
It appears to be an air core coil with a flat mica capacitor followed by a multi-wired switch, it does nothing more than shift the frequency. The only downside to all this is that it is hard to align anything properly, it's mainly to bring in R4 LW only.
If a pic is needed of the converter, feel free to ask and I' ll take the back off it to photograph.

Regards, Rick.

[coopzone]

Hi Rick,

I would very much appreciate a photo or two showing as much detail as possible. If at all possible the connections to the chassis/radio.

Thanks in advance, and have a great new year!

Derek

[martin_m0nxp]

Going a bit off-topic here, but I personally think the Bluetooth additions (or, if you must, conversions) aren't such a bad thing - in fact I'm currently adding it to a radio I'm working on now. There's next to no content left on AM, and to make matters worse there's so much electrical noise in most households now (mine included) that even using low-power AM modulators isn't a perfect solution (and legally dubious).

Adding the function to receive Bluetooth audio (ideally by re-purposing the band switch to avoid cosmetic changes) gives the radio a useful purpose. It also avoids any potential safety issues as there's no external connection to any internal electronics.

You can't really quote sound quality as a reason not to use Bluetooth either - the more modern codecs (which all modern phones and a lot of receiver modules support) give sound quality comparable to lossless compression. Given the reduction in bandwidth and added distortion the valve output stage adds you'd never tell the difference between Bluetooth and a cable.

Like everything though there are good and bad ways of doing it. Personally I'm aiming to leave all original circuitry present, even if disconnected, so the mod could be fully reversed, and making no changes to the appearance of the radio. I'm also leaving the MW band fully functional.

[Glowing Bits!]

I have taken a few pictures of the board, the capacitor is not used, there are 6 wires exiting the coil, the red wire in pic 3 goes to v1 grid, the grey wire goes to the original MW coil by the tuning gang, I can't remember where the other 4 wires go to, they're under the chassis somewhere.
Sorry for the late reply, I've got a severe (and damn annoying) cold at the moment, everything is on a go-slow.
Rick.

[Phil G4SPZ]

I had a GEC-built Civilian Set which had the long wave mod. It consisted of two additional coils, one in parallel with the aerial coil and one in parallel with the local oscillator coil, switched in and out by a two-pole toggle switch on the rear panel. It actually worked very well once restored. Radio 4 (198kHz) appeared roughly half-way round the dial, with some coverage either side.

I don't have the set any longer, as I donated it to the Cable Museum in Porthcurno for their WWII display cabinet - to replace the 1946-vintage set they originally had in there!