Redifon R153.

[gm0ekm cecil]

I have been trying, without any success, to find any info relating to the Redifon R153 communications receiver. the set is identical in appearance to the R50M. The R153 forms part of my wireless museum.
Any ideas anyone?

Cecil.

[gm0ekm cecil]

Does anyone know the frequency bands of the Redifon R50M, I think my R153 may differ.

[Darren-UK]

A quick Google told me the R50M is 13.5-26 kHz, 95 kHz to 32 MHz, AM. That's from this site.

[gm0ekm cecil]

R153 frequency bands are:-

A=15.5. to 32 Mc/s B = 7.5 to 16 Mc/s. C = 3.8 to 8 Mc/s. D = 1.5 to 4Mc/s. E = 95 Kc/s to 250Kc/s. F = 48 to 100 Kc/s. G= 25 Kc/s to 50 Kc/s.
H = 13.5 to 26 Kc/s.

I suspect that explains the difference in the two types.

Regards.
Cecil.

[gm0ekm cecil]

Unusual to find any reference to this particular set on the www, I wonder what particular purpose this type was designed and used for.

[gm0ekm cecil]

Redifon R153 photo's.

[Dave757]

Hi

What a lovely set. I wonder if the Serial number PPM1 suggests
a pre production model. This could be borne out by the model number
also being engraved rather than printed on the plate.

Kind regards

Dave

[HamishBoxer]

That indeed is a lovely set and i will second that it is a pre production model.

[G8BBZ]

Hi Cecil,
Nice pics - thank you.
I see that there is a toggle switch on the front panel - below and left of the bandswitch - which is not present on the R50. What is the function of this switch? - I just cannot read the legend on the photo.
It also looks like the audio output transformer is located on the chassis immediately behind the front panel on the left side adjacent to the output valve. This was the original location in the R50 but the output transformer was relocated to the separate power supply chassis very early on (from ser.No.50 maybe) so if this set has the transformer in the original location it may infer that it is very early. Have you found any date codes on any of the components?
I am not sure about that strange serial number. The R153, like the R186 and R50B, was a variant of the production R50 rather than a separate product line in its own right. As such I see no reason why it would have gone through a pre-production stage. Also, the nicely engraved label looks a bit 'posh' for pre-production.
A fascinating bit of kit in exceptional condition.
cheers
Peter G8BBZ

[gm0ekm cecil]

The toggle is the on/off switch on the R153 for the noise suppressor. I'll check for any component date etc. later on, at present the building housing my collection is hired out for a series of workshops (not radio related) A bit of a mystery why this receiver doesn't cover the 500KHz segment.
Cecil --- GM0EKM.

[turretslug]

Judging by the 6U device on the left of the first picture (RA17?), the Redifon must be one big radio. Good to see the trim tools still present- if only that was more often the case! A set capable of hearing Grimeton on 17.2kHz, too- presumably Shetland almost counts as "local" for this transmission.

[agus_h_y]

Hi All

Im interested in this Thread, especially talking about Redifon Receiver. I just bought Redifon R150 serial 290 from local antique seller here in Jakarta (Indonesia).

Now i m in the middle restoring this receiver. Re Caps and some Re resistors already done. IF1 and IF2 transformer is open circuited (big headache). S meter is burn.

The interesting thing is, this receiver is very mysterious, there is no information at all on the NET. If you have any story about this receiver i ll be very happy to learn.

The schematic i use now, is from Redifon model R50 even only 80% similar.

Again thank you for whatever you have, i will post the pictures, but i must learned first how to do it.

Best Regards from Jakarta

Agus (yb0djh)

[AC/HL]

Hi Agus, and Welcome,
This should help you: https://www.vintage-radio.net/forum/...ad.php?t=77650

[G8BBZ]

Hi Agus,
I believe the R150 was a "cut down" version of the R50M.
I think you have no coverage below 550kHz, a single frequency IF on 465kHz and the mains power supply in the receiver chassis. It would be very good if you can post some photos - I have never seen one of these receivers.
As to what they were used for - don't know. Obviously not a marine application as all the LF/MF coverage has been omitted. There were a number of variants of the R50 produced in the 1950's, presumably to satisfy a particular customer requirement or market opportunity.
Good luck with the restoration.
cheers
Peter G8BBZ

[agus_h_y]

Hi Peter.

Thank you for the response of Redifon R150 s/n270. Thats true, the R150 is the cut down version of R50M. There is no selector to band below 550 khz, instead at the band selector, there is the duplicate band ABCDE but in Crystal Osc Mode not VFO. Inside the VFO Cage there is the Crystal socket.

Correct, only 465 KHz IF line. No 110 KHz IF.

PSU build in, Audio output transformer already in. There is a Jack at rear panel for speaker. On the right side of rear panel, there is a jack with many plug in, i think that is for muting or something.

There is Jack designated to IF Out at front panel. I follow the route, the connection is connected to the last IF Transformer.

Now busy with so many damage. Primary of IF 1, IF 2 need to be re-wounded. S meter was burned out. Some wiring was open by rat bites. Audio Potentiometer was open circuited.

Will updated on coming progress.
Agus / YB0DJH

[G8BBZ]

HI agus,
Many thanks for posting the pictures of the R150.
I was not aware of the crystal control option on this receiver - very interesting. Also the IF output - this is a common feature but normally appears as a a socket on the rear chassis of the receiver, not on the front panel. Having said that, the hole in the front panel for the IF output looks as though it might be a modification rather than factory fitted,
The IF output was usually fitted for use with an external FSK Demodulator for use with teleprinter traffic. That and the crystal control option makes me think that the receiver may have been used in some sort of HF point-to-point teleprinter service as was common in aviation, press and similar services at the time.
Any chance of a picture of the Crystal oscillator unit?
cheers
Peter G8BBZ

[agus_h_y]

Originally Posted by AC/HL

This should help you: https://www.vintage-radio.net/forum/...ad.php?t=77650

Hi Bill,
Thanks for your help. I cannot find such kind of service in BVWS, maybe I missed the web navigational.

Anyway, I will try to build RFC winder, at this moment I fix the other part of radio, such as meter, AF filter etc.

Originally Posted by G8BBZ

Any chance of a picture of the Crystal oscillator unit?

Hi Peter
Here is the picture of Redifon R150 With Xtal Socket. At the rightmost there is a Xtal Socket. Osc tube is ECC33.

The bottom side all IF can was removed.

BR

Agus

[agus_h_y]

Hi All

Updating my progress on Redifon R150 restoration. I managed to fix the IF Transformers and radio works fine on Band E and F. Band A-B-C-D silent and later i found the Local oscillator is not oscillating.

Local Oscillator using ECC33 / 6SN7GT dual triode. I will attach the hand writing schematic latter on. Last night i try to make schematic from radio, i suspect there are some "changes" on radio and i will try to restore it back to original schematic, and some component i cannot identified what is the original value.

Very frustrating to make oscillator starts, without any reference. Anyone knows about the schematic of R150, especially in Local oscillator section it will be appreciated if you would share it to me.

Thank You Very Much

Agus

[G8BBZ]

Hi Agus,
I am guessing here, but it seems likely that the variable frequency local oscillator would be the same as the circuit in the R50 (using the same oscillator coils at least), which used the L65/6J5 as the local oscillator valve. I guess the move to the ECC33/6SN7 in your R150 was to provide a second triode for the Xtal oscillator function without needing to find space on the chassis for another valve..
So if you have the circuit for the R50 then I think it is likely that this will be the variable local oscillator circuit for the R150 also.
hope this helps
cheers
Peter G8BBZ

[agus_h_y]

Hi Peter

Thanks for responding my post.
Finally i fixed the Local Oscillator, the culprits were the 3 (three) caps. First capacitor is the coupling to Oscillator Coils, second and third caps is the bypass from first plate and second plate of triode.

The oscillator finally i can configure it out as Butler Oscillator, so the both Triode is working for oscillating function. When in XTAL mode, the XTAL is connected from cathode to cathode. It is a clever configuration. When in VFO mode, they used plate tune oscillator.

So now band BCD is working, the remaining bands are easy, because i know for sure RF coils are open circuited due to copper corrosion inside the wax. I don't know why.

Pfew....

Thank you
Agus.