XV50 on 70MHz
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I have been very pleased with My K2 which I purchased at Dayton back in
2005. So pleased, that I have persuaded a few others to take the plunge and build K2s, here in the UK. I have been looking at the feasibility of building an Elecraft XV50 for the 70MHz band to use with my K2. Interest in this band is mushrooming in Europe with new countries gaining 70MHz allocations almost on a monthly basis. ( http://www.70mhz.org ) The modifications required would seem to be fairly straightforward but I have no illusions to be an RF design engineer! The Mitsubishi RA30H0608M power module would be a drop in replacement for the M57735 (using the XV144s biasing circuit). There would need to be a few L and C value changes in the TX LPF and the mixer BPF too. The LO would have to be changed to 42MHz (from 22MHz). I am a bit confused on the choice of driver SGA7489 in the XV50, ERA-5 in the XV144 and back to the SGA7489 in the XV222. Presumably the SGA7489 would be OK at 70MHz? Has anyone on the list already done all of the above? I have no wish to re-invent the wheel. I would be pleased to hear of the component values required. There does not appear to be anything specific in the archive. Whilst I am aware that Elecrafts core market is in the US and Canada, I think they are missing an opportunity to create a successful new product for a very minimum of R&D effort. I think an Elecraft XV70 would do well in Europe as there is a lack of any competition for equipment on this rapidly expanding band. The XV series have very flexible interfacing and I am sure would prove a popular way for stations to get on the band with their existing HF transceiver. It may even encourage a few more European VHF hams to go on and build a K2 as well! 73 Allan GM4ZUK _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In message <002301c6a658$c88685f0$6401a8c0@allan8100>, Allan Duncan
<[hidden email]> writes snip >Whilst I am aware that Elecraft’s core market is in the US and Canada, I >think they are missing an opportunity to create a successful new product for >a very minimum of R&D effort. I think an Elecraft “XV70” would do well in >Europe as there is a lack of any competition for equipment on this rapidly >expanding band. The XV series have very flexible interfacing and I am sure >would prove a popular way for stations to get on the band with their >existing HF transceiver. > >It may even encourage a few more European VHF hams to go on and build a K2 >as well! Totally agree with Allan's post above. I am currently 'modding' my old 6m transverter back to 4m, but would buy an XV70 without hesitation. Trev G3ZYY -- Trevor Day UKSMG #217 www.uksmg.org _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Allan G Duncan
Yep Allan... I'm here ..
ready to build a 70 mhz transverter if there is one from Elecraft ( with components included ) !!! hope cu from Jean louis 3A/F5NHJ.. if needed.. K2 #5371 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Allan G Duncan
I have been so pleased with my XV50 that I have just started using on
6m, that I would jump at the chance to buy an XV70 to be QRV on 70MHz. Please Elecraft, think seriously about producing one. 73 de Chris, G4BUE On 13 Jul 2006 at 9:45, Allan Duncan wrote: > I have been very pleased with My K2 which I purchased at Dayton back > in > 2005. So pleased, that I have persuaded a few others to take the > plunge and > build K2s, here in the UK. > > I have been looking at the feasibility of building an Elecraft XV50 > for the > 70MHz band to use with my K2. Interest in this band is mushrooming > in > Europe with new countries gaining 70MHz allocations almost on a > monthly > basis. ( http://www.70mhz.org ) > > The modifications required would seem to be fairly straightforward > but I > have no illusions to be an RF design engineer! > > The Mitsubishi RA30H0608M power module would be a drop in > replacement for > the M57735 (using the XV144s biasing circuit). There would need to > be a few > L and C value changes in the TX LPF and the mixer BPF too. The LO > would have > to be changed to 42MHz (from 22MHz). I am a bit confused on the > choice of > driver SGA7489 in the XV50, ERA-5 in the XV144 and back to the > SGA7489 in > the XV222. Presumably the SGA7489 would be OK at 70MHz? > > Has anyone on the list already done all of the above? I have no > wish to > re-invent the wheel. I would be pleased to hear of the component > values > required. There does not appear to be anything specific in the > archive. > > Whilst I am aware that Elecrafts core market is in the US and > Canada, I > think they are missing an opportunity to create a successful new > product for > a very minimum of R&D effort. I think an Elecraft XV70 would do > well in > Europe as there is a lack of any competition for equipment on this > rapidly > expanding band. The XV series have very flexible interfacing and I > am sure > would prove a popular way for stations to get on the band with > their > existing HF transceiver. > > It may even encourage a few more European VHF hams to go on and > build a K2 > as well! > > 73 > > Allan > GM4ZUK > > > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi...
Please : Give us the XV70 !!! Looking all around the world 4 mts transverter is a dream, Monaco, Portugal (+ Azores ) and other countries are open now on 4 mts.. When we found a dealer there is no more this, no more that, we have to wait til October etc. At the end of the story it is a 6 in 4 old box transveter or something like "golden box" looking with the money and time invested. Seriously a XVx0 looks better no..? 73 to all jean louis K2 #5371 http://perso.wanadoo.fr/f5nhj/ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Allan G Duncan
I am working on it. My plan is to make as few changes as possible while maintaining adequate performance. This will be a compromise but should make it easier to modify existing units.
I will put the instructions on my web pages (www.mike-willis.com) when ready. I have done the design work but I am now waiting for some parts to arrive before testing the modifications. The longest lead item is the 42MHz crystal. The most expensive new part will be the power module, though not for new builds as Elecraft are now using a MosFET module that covers 70MHz already. Mike |
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In reply to this post by Trevor Day
I too would be interested in buying an XV70, or a XV50 kit and applying mods as part of my build.
-- 73, M0XDF, K3 #174
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I am making good progress. I managed to find an XV50 locally to do a trial conversion. I will end up with two but perhaps someone will want one of them. It has taken 5 hours because I was also writing the documentation which will be on my web pages.
So far, I have managed to get the receive side working. I have converted the LO to operate at ~42 MHz with a 3rd overtone crystal and inductive tuning. My LO is actually 41MHz as I only had a crystal for that frequency. I have re-tuned the LO filter and see a nice clean signal on my scope. To bring the converter into band I only changed the resonator and input/output capacitors in the mixer band pass filter. The coils should really change too but will be very tricky to remove. Currently as a result the filter is a little lossy and not very sharp. I have not yet modified the front end preamplifier, I found it almost tunes with minimum C1. It works well enough to allow me to receive signals on the band, limited by band noise. I will look at improving the preamplifier but so far have left it alone to avoid the risk of damaging the FET. Conversion gain, 70.25MHz to 29.25MHz is 24 dB. Later in the week I will start to pay attention to the transmitter side and replacing the PA module and low pass filters. Mike |
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Well, I'd be doing this on a new unbuilt XV50, so if changing coils is good and someone can document what that change is ...
I'm quite capable of assembly, but not of design.
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In reply to this post by Allan G Duncan
Hi I converted an XV50 to 70MHz at the end of 2006 and have used it (with my K2) on SSB and CW during a few of the RSGB 70MHz contests in 2007. I have been very pleased with the performance of that combination - particularly on CW. I have access to a modern spectrum analyser - both the two tone TX IMD and spurious performance were similar to an unmodified XV50. I purchased replacement L's and C's from Mouser in the USA. The L's are made by a company called Xicon and are identical to those originally fitted. I suspect that Mouser supply Elecraft themselves with the L's in their transverter designs. Unfortunately, since I purchased mine, the minimum order quantity for these has been increased from 1 to 10,000 from Mouser (www.mouser.com) and I have been unable to find another supplier anywhere. The XV50 2nd harmonic trap (C58, C59 and L3) will need to be removed for 70MHz. If I get a chance this evening, I will post my component values I used to modify my XV50 to 70MHz. 73 Allan GM4ZUK _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by M0XDF
Specifying them is easy, getting them is more difficult. The problem is the part numbers used by Elecraft do not relate to something you can actually order. We need to find out what the actual part numbers are and order the coils with the next lower inductance.
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We could try asking Elecraft for the part number of those components - I
think they are a little busy right now, but give it a month or two On 8/1/08 09:31, "AD6XY - Mike" <[hidden email]> sent: > > Specifying them is easy, getting them is more difficult. The problem is the > part numbers used by Elecraft do not relate to something you can actually > order. We need to find out what the actual part numbers are and order the > coils with the next lower inductance. > > > > M0XDF wrote: >> >> Well, I'd be doing this on a new unbuilt XV50, so if changing coils is >> good and someone can document what that change is ... >> >> I'm quite capable of assembly, but not of design. >> >> >> AD6XY - Mike wrote: >>> >>> The coils should really change too but will be very tricky to remove. >>> Currently as a result the filter is a little lossy and not very sharp. >>> >> >> -- I never did a day's work in my life; it was all fun. -Thomas Edison _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Allan G Duncan
Allan and all,
I have seen the high minimum order problem when attempting to purchase parts that were listed on an older parts list. There is usually an alternative. As a generalization, situations where the minimum order quantity from Mouser (or DigiKey) has increased to a huge number has been created by a change to RoHS compliant parts. You are likely trying to purchase a non-RoHS version. Normally the same part in a RoHS compliant version is offered *but* has a different part number - scanning the product pages will often reveal the equivalent part that is available with a minimum quantity of one. 73, Don W3FPR Allan Duncan wrote: > > Unfortunately, since I purchased mine, the minimum order quantity for these > has been increased from 1 to 10,000 from Mouser (www.mouser.com) and I have > been unable to find another supplier anywhere. > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Allan G Duncan
Thanks Allan,
I have managed now to get to an output of about 0 dBm from the driver stage. I have not got the power module in as I doubt it will work on 70MHz. I will replace it with one that does. The 0 dBm is a little disappointing but I know why and am working on fixing that. The harmonic trap you mention is actually a low pass filter. I have modified it for 42MHz. I have also modified the low pass filter at the output. The band pass filter is currently half modified, the same coils but different Capacitors. When I completely finish the modification, I will post a link to a web page with the full details. If it is ppossible to maintain performance with the original coils, it is a much better option than buying 10,000 to replace 3 of them. I am interested in your component values, especially for the LNA Mike http://www.mike-willis.com/XV70_Pt1.htm
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In reply to this post by M0XDF
I have now completed my modification by installing the replacement power module. The changes required to fit the new module are very simple, it is just a matter of removing 2 links and one inductor and installing one link and two resistors, plus the module.
Power output of 20W was achieved immediately for -20 dBm input. The power will easily go beyond 30W but the heatsinking is not adequate even for 20W so I recommend keeping it to 10W or less. If the gain is too high, the resistor supplying the driver stage could usefully be changed to the same value as in the XV144. My receiver noise figure measurement attempts were thwarted by our local 70 MHz beacon. However, setting the measurement bandwidth to 100kHz allowed me to measure the noise figure at 69MHz which was ~1.5 dB. This could no doubt be improved by replacing L1, but is good enough for 70MHz already. I have not done a 2 tone test yet, I will try this later. The results should be as good as the XV50 and 10W is will below the maximum output. Mike PS - Can anyone make an appropriate XV70 indicator for the front? |
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