Dave Richards AA7EE

December 30, 2014

New Source Of Resonators For 40M

Yesterday, Joel KB6QVI, tipped me off to a new source for ceramic resonators that look as if they should be a godsend for anyone building a simple QRP rig for the phone portion of 40M (such as VK3YE’s Beach 40) – that’s if they perform according to specifications.  A while back, we both bought some Murata resonators with a specified frequency of 7.2MHz, only to find that the very highest frequency they would oscillate at was 7.15MHz. Cecil K5NWA runs an online parts site called The Parts Place, and is listing a 7.28MHz resonator. The description says,

“Tunes over a wide frequency range. With 100 pf capacitor a shift of 7036KHz – 7284KHz is expected – will verify when parts arrive, do not use the center pin.

Note that for a lower top frequency, put a fixed small polystyrene capacitor in parallel with the adjustable capacitor, which can be made smaller.”

Joel and I ordered 20 each, and Patrick W9PDS said that he was going to purchase some as well. When Joel first found them, there were 167 available – there are now 127* as I write this.  They are 30 cents apiece, 22 cents if you buy 10 or more, so it would seem worth picking up a few for the parts bin, as resonators that are usable in the upper portion of 40m don’t come along too often. The last time we found good ones was from hamshop.cz, and they have been out of stock for months now.

Please note that we haven’t yet received ours and don’t know whether they will resonate reliably within a usable range of frequencies but for home-brewers, this is worth a try while they’re available. If they are indeed usable, let’s hope that Cecil is able to get more in once the current lot is sold out. Incidentally, Cecil’s site is easy to use. I received e-mail status updates to verify that the order had been received, then another one to verify that payment had been received, and another one to notify that the order had been approved – all in short order. I assume that there will be another when the order has shipped. With a business like this, being run by an individual ham, this level of notification already surpasses what I would expect.

My soldering iron hasn’t been seeing much action lately, but Joel is an inspiration at the workbench; I have lost track of the sheer number of projects he has put together since I have known him. Doubtless he will verify that these are usable for ham applications once his arrive and I’ll post the results here once that happens. If I happen to put one of mine into a test circuit, I’ll let you know what happens with that too

Here’s the link once again (opens in a new window), and thank you to Joel for bringing this to our attention.

*As of 16:25 UTC (8:25am PST), there are now just 88 available.

NOTE – Steve G1KQKH, in the comments below, noted that this same resonator is available from Mouser. Check the comments section for his link to UK Mouser. If you’re in the US, the link is here (opens in a new window).

8 Comments »

  1. Dave, and others the main source of these might be Mouser?

    http://uk.mouser.com/Passive-Components/Frequency-Control-Timing-Devices/Resonators/_/N-6zu9h?P=1z0wmulZ1z0z5h6

    73 Steve

    G1KQH

    Comment by Steve — December 30, 2014 @ 8:40 pm | Reply

    • Thanks for the tip Steve. I think these must be a fairly new product line. I don’t remember seeing them on Mouser a few months ago.

      Dave
      AA7EE

      Comment by AA7EE — December 31, 2014 @ 1:39 am | Reply

  2. I’m currently using a different model of Murata resonator in my Beach40 – ZTA73728MT. The old one is rated at 7.3728 and I can get 7170 – 7410 out of it. I plan on taking this new find from Dave & Joel and installing it with a switch to hopefully let me cover 7036 – all the way up to 7410. This will be an easy & fun mod to make!
    W9PDS

    Comment by Patrick Skerrett (@W9PDS) — December 31, 2014 @ 1:22 am | Reply

    • I didn’t know about the 7.3728 one Patrick – thanks!

      Dave
      AA7EE

      Comment by AA7EE — December 31, 2014 @ 1:38 am | Reply

  3. Correction on the model # of the 7.3728 resonator. You can search for it on Mouser by – 520-ZTA7.3728MT. 73s

    Comment by Patrick Skerrett (@W9PDS) — December 31, 2014 @ 2:05 am | Reply

  4. There is quite a high shipping rate I have found with Mouser if the order value is under £50 here in the UK, makes a 100 resonators double their value! The best way is to club together and order in bulk from them. You never know you might fancy a few other items at the same time?

    Saying that I have always found their service quick and very good!

    It will be interesting to see what pulling range you all achieve?

    73 Steve

    G1KQH

    http://g1kqh.blogspot.co.uk/

    Comment by Steve — December 31, 2014 @ 10:57 am | Reply

    • Steve – not sure how it is in the UK, but with Mouser in the US, for small orders, you can request that they be sent via regular First Class Post Office mail. It is not offered as an option on the website, but if you note it in the comments, they will do it. I usually make a quick phone call after placing the order to verify that it will be sent via regular mail. I’d be interested to know if Mouser UK do that too.

      I think I have a test circuit for resonators around here somewhere. I’ll slip one of the new ones into it and see what happens. Will report back. No doubt Joel will test his too,

      Dave
      AA7EE

      Comment by AA7EE — December 31, 2014 @ 4:05 pm | Reply

  5. Dave, Count yourselves lucky over there, as the only options Mouser seem to offer here are £10 postage, or buy over £50s worth of goodies and shipping is free! Many other suppliers do this now here in the UK, some not quite as high as this amount may I add! Most of these sort of companies are geared up to serve big industry, not small fry penny pinching Amateurs. Saying that Non of them refuse your money anymore like RS used to. Normally I hang fire for a while because there is always something else I will need to stick on the account to make it up to the free barrier..

    73 Steve

    G1KQH

    Comment by Steve — December 31, 2014 @ 4:37 pm | Reply


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