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admin - Monday, December 19, 2011 at 03:46:49
Manufacturer: Grundig. Model 3028; “Marlborough”

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Photo. submitted by maitu: Dec. 2011.
Comments by Al.(Skywave): Dec. 2011
admin - Monday, December 19, 2011 at 03:46:32
Manufacturer: Grundig. Model 3028; “Marlborough”

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Photo. submitted by maitu: Dec. 2011.
Comments by Al.(Skywave): Dec. 2011
admin - Monday, December 19, 2011 at 03:41:09
Manufacturer: Grundig. Model 3028; “Marlborough”
Photo. shows unit after restoration.

► Brief spec.:
MW/LW/SW/VHF + gram.
Multiple speakers + tone ctrl.
Valve line-up: ECC85, ECH81, EF89, EABC80, EL84, EM84 + metal rect.

► Maintenance notes:
May need dropper for 230v.a.c. input: check mains xfmr.
Check mains wiring; may need redo for 3-core.
Recorded faults: U/S EL84 & intermit. o/c pri. on O/P xfmr.
EM84 can be faulty.

► Collector's note:
Three variants: German: 3028/hi-fi; export: 3028/3D; UK: 3028

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Photo. submitted by maitu: Dec. 2011.
Comments by Al.(Skywave): Dec. 2011
admin - Saturday, December 17, 2011 at 17:28:52
shown with wronge wave chang switch
admin - Friday, December 16, 2011 at 14:27:58
Tektronix 465 oscilloscope.
A member of the 455/465/475 highly-compact portable 'scopes from Tek., dating from the late 1960's to mid 1970's.

With so much known about these venerable models - and so much info. available on the 'Net - there seems little point in describing their spec. etc. in detail.
A 'scope is a useful adjunct to any electronics workshop, and Tek. have always been market leaders in this field. When properly set-up and calibrated, a Tek. 'scope takes a lot of beating on sheer performance!

► Collector's and repair's notes.
Tek. 'scopes of the 455 / 465 / 475 family frequently become available on the second-hand market, although occasionally as "Not working, spares only". The 475 has the highest spec. and it more than adequate for most domestic broadcast set repairs. The repair of a Tek. 'scope in this family is most decidedly not a trivial affair, and the prior acquisition of the appropriate manual is a must! Plenty of time, patience and precision tools are required.

Common faults include 'sticky' shift controls, inaccurate or non-functioning Y-input attenuator positions, no or 'unshiftable' trace, various time-base failures. Many of these faults can be fixed by very careful cleaning of switch contacts and location and replacement of failed components. All the small-signal transistors are located in sockets which helps and despite the Tek. unique part numbers for these, many of them can be replaced by 'conventional' types; for example, the power-switcher for the HV transformer can be replaced by a metal-case 2N3055. Unfortunately, however, there are a number of Tek. hybrid 'specials' in these models, and although they can be obtained, they can be expensive. The EHT multiplier and HV transformer have been known to fail and replacements for these can be difficult to obtain. Note that some parts from one model, such as the HV transformer, is different in the 455 and 475, so a direct swap cannot be done for diagnostic purposes. If in doubt, refer to the manual(s) - or ask me!

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Photo. and comment by Al. (Skywave): Dec. 16, 2011.
member - Friday, December 16, 2011 at 11:32:36
Murphy B40D Receiver.
The updated version of the original B40 receiver, this receiver is enabled for wide and narrow FSK reception and is also fitted with a Local Osc. trim control on the right hand panel.
The receiver shown is from HMS Ark Royal and is well used, however it's all workie workie with all of it's original components though an overhaul is due at some point. The tuning gearbox has some backlash due to heavy wear, it is still usable and is a good performer. In the FSK positions I have re aligned the BFO trimmers for upper and lower sideband reception in both wide and narrow modes for amature band SWL.

Lawrence 16/12/2011.
admin - Thursday, December 15, 2011 at 17:51:47
Eddystone 830/7. Vintage: 1962-1973.
Gen. coverage comms. receiver. 300 kc/s - 30 Mc/s in 9 bands. A double s/het. with both local oscs. tunable: 1st. IF: 1250-1450 kc/s; 2nd. IF: 100 kc/s. (incremental tuning). Uses 15 miniature valves (B7G / B9A); silicon diodes in PSU.
The design incorporates a wide-range of user-controls to cope with the various conditions of reception found on the HF bands - and this was reflected in the price when they were originally available as new. Little expense was spared in the design of this receiver and it was aimed at the professional market ~ as well as the more-affluent members of the Radio Amateur fraternity!

Their are variants of this model in existence: the 830/7 is the commonest found. The general reference is "the 830", with the /number defining the particular variant.

► Collector's note.
Always in great demand when these sets do appear on the S/H market, and when they do, they are usually in excellent condition. I have known of some examples to sell for over £700 when changing hands!
The variants are few and far between, although the 830/4 is found occasionally in North America.

►Maintenance note.
Not wishing to state the obvious, but apart from routine C & R replacement, anything more serious by way of maintenance should only be undertaken with the manufacturer's manual and with a thorough understanding of the various frequency conversion processes. However, having said that, in my experience, the main reasons for maintenance is simply to check that the model under test meets its published spec. - which on account of the design and the care these receivers usually get - often requires little adjustment.

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Photo. & comment by Al. (Skywave): Dec. 15, 2011
admin - Thursday, December 15, 2011 at 17:09:27
The main reason I added this photo. is simply because this receiver is so common, that a photo. of what it looks like inside may be of interest to collectors and repairers alike.
Al. / Dec. 15, 2011
admin - Thursday, December 15, 2011 at 17:07:22
Eddystone 940. Vintage 1962-1970.
Gen. coverage comms. receiver: 480 kc/s - 30 Mc/s in 5 bands:
480 - 1030 kc/s; 1.03 - 2.4 Mc/s; 2.4 Mc/s - 5.4 Mc/s; 5.4 - 12.7 Mc/s; 12.7 - 30.0 Mc/s.
2 RF stages; 2 IF stages (470 kc/s); crystal filter; variable selectivity; S-meter; BFO.

► Collector's notes.
A very popular comms. receiver and always in great demand on the S/H market. Frequently found in enthusiasts' collections.
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Photo. submitted by Al.(Skywave): Dec.15, 2011.
admin - Thursday, December 15, 2011 at 16:49:20
Eddystone manufactured a variant of the Mk.II, the EC10A2. There were several sub-variants of this: basically. the arrangements for mounting (rack, bench, etc.) The significant difference in the A2 model (compared to the 'ordinary' model) is that the 'A2 series constitute a set of receivers for marine applications with a fixed channel (crystal-controlled) at the distress & call freq., 2182 kHz.

► Collector's note.
An uncommon set, but one does appear on the S/H market now and again, albeit infrequently.

► Maintenance note.
The I.F. is changed to 720 kHz in this model.

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Comment added by Al.(Skywave): Dec. 15, 2011