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The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi all I have built a small QRP TX using tubes/valves for 500kc/s, it fits on the palm of the hand, sans PSU. Because finding Xtals for the band seems impossible I use two rocks and mix them, then VXO them onto frequency. 6.500-6.000 are pretty standard frequencies the difference equals 500kc/s (I have my 472 xtals ready ... :-). The tube line up is 12AX7 oscs - 6AU6 mix driver - 6CL6 PA. This line up gives 4Watts RF at the antenna socket. Its a fun rig for local use, strictly retro no solid state down to cathode keying using a relay. Recently used the second pair of contacts on the relay to key the osc cathode to eliminate the leaking through of carrier during RX. The effect on keying quality is minimal which came as pleasant surprise. Two way contacts have mainly been local but beacon reports using Opera have come from near EU counties namely PA0 land. This rig line up has been use in two other Tx's one 160/80m CW AM (choke mode with another 6CL6) (FM) FSK worked most of the UK on AM (3.615) and a 10m CW - FSK only version that uses a third O/T xtal but at full power I get chirp (work still to do). Both these rigs dispensed with the 6AU6 stage. For a full retro style the use of none usable old style frequency crystals with internals removed and a modern xtal fitted inside the cases is a possibility but don't expect this to give rugged reliability if used in a "Power" oscillator design. If the older Xtal is of the plate variety and can be dissembled, raising the frequency can be achieved by edge "grinding" the slab i.e a light polishing. Skill is needed as the edge must be kept square for it to work and there is always the risk of fracturing or just stopping the xtal from vibrating by this technique. Please report success or lack of it. Tubes are here to stay! [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [77.238.189.21 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (m0fmt[at]yahoo.co.uk) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 0c28add2673aaa1c8f62f1695e18ff8b Subject: Re: LF: FT-241A xtals? Content-Type: multipart/alternative; boundary="131296447-1251172271-1355825158=:3315" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_FONT_BIG, HTML_MESSAGE,TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-ma04.r1000.mx.aol.com ; domain : yahoo.co.uk DKIM : fail x-aol-sid: 3039ac1d600c50d0407d0ff1 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --131296447-1251172271-1355825158=:3315 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi all=0A=A0=0AI have built a small QRP TX using tubes/valves for 500kc/s, = it fits on the palm of the hand, sans PSU. Because finding Xtals for the ba= nd seems impossible I use two rocks and mix them, then VXO them onto freque= ncy. 6.500-6.000 are pretty standard frequencies the difference equals 500k= c/s (I have my 472 xtals ready ... :-). The tube line up is 12AX7 oscs - 6A= U6 mix driver - 6CL6 PA. This line up gives 4Watts RF at the antenna socket= . Its a fun rig for local use, strictly retro no solid state down to cathod= e keying using a relay. Recently used the second pair of contacts on the re= lay to key the osc cathode to eliminate the leaking through of carrier duri= ng RX.=A0The effect on keying quality is minimal which came as pleasant sur= prise. Two way contacts have mainly been local but beacon reports using Ope= ra=A0have come from near EU counties=A0namely PA0 land.=A0=0A=A0=0AThis rig= line up has been use in two other Tx's one 160/80m CW AM (choke mode with = another=A06CL6)=A0(FM) FSK worked most of the UK on AM (3.615) and a 10m CW= - FSK only version that uses a third O/T xtal but at full power I get chir= p (work still to do).=A0Both these rigs dispensed with the 6AU6 stage.=0AFo= r a full retro style the use of none usable old style frequency crystals wi= th internals removed and a modern xtal fitted inside the cases is a possibi= lity but don't expect this to give rugged=A0reliability if used in a "Power= " oscillator design. If the older Xtal is of the plate variety and can be d= issembled, raising the frequency can be achieved by edge "grinding" the sla= b i.e a light polishing. Skill is needed as the edge must be kept=A0square = for it to work and there is always the risk of fracturing or just stopping = the xtal from vibrating by this technique.=A0=0APlease report success or la= ck of it. Tubes are here to stay!=0A=0A73 es GL Pete M0FMT IO91UX=0A=0A=0A>= ________________________________=0A> From: Dimitrios Tsifakis =0A>To: rsgb_lf_group@blacksheep.org =0A>Sent: Tuesday, 18 December= 2012, 8:41=0A>Subject: Re: LF: FT-241A xtals?=0A> =0A>I am glad you found= the eBay seller and your project is about to be=0A>revived. A VFO, as Davi= d G4DMP mentioned before, is also another valid=0A>option. It shouldn't be = too hard to make a VFO stable enough for 472=0A>kc, even if it is a valve o= ne! As a test, I built a VFO for 7 Mc using=0A>a 6C4 oscillator and a 6AG7 = as a BA - it was perfectly good for CW=0A>work.=0A>=0A>I hope we can exchan= ge more technical information about both projects=0A>here. Maybe this will = be a source of inspration for others that have=0A>considered the possibilit= y of using valves for a 472 kc transmitter.=0A>=0A>73, Dimitris VK1SV=0A>= =0A>=0A>2012/12/18=A0 :=0A>> What a coincidence Dimitros!= =0A>>=0A>> After answering to your posting I did a search on Ebay for FT-24= 1 crystals=0A>> and found the same seller - an order has already been made = :)=0A>>=0A>> Many thanks for bringing up this subject - I had lost hope alr= eady.=0A>>=0A>>=0A>>=0A>> Paul-Henrik, OH1LSQ=0A>>=0A>>=0A>> Quoting Dimitr= ios Tsifakis :=0A>>=0A>>> Hi Paul-Henrik,=0A>>>=0A>>>>= Yes, the same thought has been on my mind for a long time now. The=0A>>>> = problem=0A>>>> is that fundamental X-tals for this frequency band are nearl= y=0A>>>> unobtainable.=0A>>>> I have even tried to custom order some new on= es for me and a couple of=0A>>>> friends but never succeeded - the quantiti= es would need to be much larger=0A>>>> for this type of crystals. (They use= a different kind of cut as compared=0A>>>> to=0A>>>> crystals for say 3500= kHz which can still be ordered custom fairly easily)=0A>>>>=0A>>>> Hopefull= y people with a stash of suitable vintage X-tals will wake up=0A>>>> when= =0A>>>> the new band opens for real and put some up for sale if they don't = want=0A>>>> to=0A>>>> use them themselves.=0A>>>=0A>>>=0A>>> I bought a few= crystals from this ebay seller:=0A>>>=0A>>>=0A>>> http://www.ebay.com.au/i= tm/FT-241-CRYSTALS-Many-to-choose-from-You-pick-/260897401407?pt=3DLH_Defau= ltDomain_0&hash=3Ditem3cbeb26a3f&_uhb=3D1#ht_4373wt_1188=0A>>>=0A>>> There = seem to be a few left. They are sold as-is, but I found that the=0A>>> majo= rity of the ones I bought worked OK. There may be other sellers on=0A>>> eB= ay.=0A>>>=0A>>>> I'd say go for it - I have built a couple of "MO-PA" trans= mitters for=0A>>>> 80/160m, they are really pleasant and rewarding projects= with a distinct=0A>>>> sound of their own. This is especially true if you = also key the=0A>>>> oscillator.=0A>>>=0A>>>=0A>>> I have built recently a s= imilar transmitter for 40 m, using a 6CL6 and=0A>>> an 807. When I keyed th= e oscillator together with the PA, I couldn't=0A>>> get it to behave proper= ly, so I added a switch to leave the oscillator=0A>>> on and key only the c= athode of the PA. I only key the oscillator when=0A>>> I want to draw some = attention with the home-brew sound!=0A>>>=0A>>> In general, I have had diff= iculty sourcing a HV transformer suitable=0A>>> for an 807. In the past, I = found that one can build a voltage doubler=0A>>> or quadrupler, with modern= electrolytics, it is a viable alternative.=0A>>> The 6.3 V for the filamen= ts I found I can get from a 6 V transformer.=0A>>> Hint: it's easy to add e= xtra turns on a toroid type transformer :-)=0A>>>=0A>>> 73, Dimitris VK1SV= =0A>>=0A>>=0A>>=0A>>=0A>>=0A>=0A>=0A>=0A>=A0 --131296447-1251172271-1355825158=:3315 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi all
=
 
I have built a small QRP TX using tubes/valves for 500kc/s, it = fits on the palm of the hand, sans P= SU. Because finding Xtals for the band seems impossible I use two rocks and mix them, then VXO them onto frequency. 6.500-6.000 are pretty standard frequenci= es the difference equals 500kc/s (I have my 472 xtals ready ... :-). The tube line up is 12AX7 oscs - 6AU6 mix driver - 6CL6 PA. Thi= s line up gives 4Watts RF at the antenna socket. Its a fun rig for local us= e, strictly retro no solid state down to cathode keying using a relay. Recently used the second= pair of contacts on the relay to key the osc cathode to eliminate the leaking through of carrier during= RX. The effect on keying quality is minimal which came as pleasant su= rprise. Two way contacts have mainly been local but beacon reports using Op= era have come from near EU counties namely PA0 land. =
 
This rig line up has been us= e in two other Tx's one 160/8= 0m CW AM (choke mode with another 6CL6) (FM) FSK worked most of the UK on AM (3.615) and a 10m= CW - FSK only version that u= ses a third O/T xtal but at = full power I get chirp (work still to do). Both these rigs dispensed with the 6AU6 stage.
For a full retro style the use of none usable old style frequency crystals with intern= als removed and a modern xtal fitted inside the cases is a possibility but don't expect this to give rugged reliability if used = in a "Power" oscillator design. If the older Xtal is of the plate varie= ty and can be dissembled, rais= ing the frequency can be achieved by edge "grinding" the slab i.e a light p= olishing. Skill is needed as the edge must = be kept square for it to work and there is always the risk of fracturi= ng or just stopping the xtal= from vibrating by this technique. 
Please report success or l= ack of it. Tubes are here to stay!
 
73 es = GL Pete M0FMT IO91UX
From: Dimitrios Tsifakis <dtsifakis@gmail.com>
To: rsgb_lf_group@blacksheep.org
= Sent: Tuesday, 18 Decembe= r 2012, 8:41
Subject: = Re: LF: FT-241A xtals?
<= /font>

I am glad you found the eBay seller and your project is a= bout to be
revived. A VFO= , as David G4DMP mentioned b= efore, is also another valid
option. It shouldn't be too hard to make a = VFO stable enough for 472kc, even if it is a valve one! As a test, I built a VFO for 7 = Mc using
a 6C4 oscillator and a 6AG7 as a BA - it was perfectly g= ood for CW
work.

I hope we can exchange more technical information about= both projects
here. Maybe this will be a source of inspration for others that have
considered th= e possibility of using valves for a 472 kc transmitter.

73, Dimitris VK1SV

2012/12/18  <phl@netikka.fi>:
> What a coincidence <= span id=3D"misspell-31" class=3D"mark">Dimitros!
>
> Aft= er answering to your posting I did a search on Ebay for FT-241 crystals
> and found the same sell= er - an order has already been made :)
>
> Many thanks for brin= ging up this subject - I had lost hope already.
>
>
>
= > Paul-Henrik, OH1LSQ
>
>
&= gt; Quoting Dimitrios Tsifakis <dtsifakis@gmail.co= m>:
>
>> Hi Paul-Henrik,
>>
>>> = Yes, the same thought has been on my mind for a long time now. The
>&= gt;> problem
>>> is that fundamental X-tals for this frequency band are nearly
>&g= t;> unobtainable.
>>> I have even tried to custom order some= new ones for me and a couple of
>>> friends but never succeede= d - the quantities would need to be much larger
>>> for this ty= pe of crystals. (They use a different kind of cut as compared
>>&g= t; to
>>> crystals for say 3500kHz which can still be ordered c= ustom fairly easily)
>>>
>>> Hopefully people with a stash of s= uitable vintage X-tals will = wake up
>>> when
>>> the new band opens for real an= d put some up for sale if they don't want
>>> to
>>>= ; use them themselves.
>>
>>
>> I bought a few c= rystals from this ebay selle= r:
>>
>>
>> http://www.ebay.com.au/itm/FT-241-CRYSTALS-Many-to-choose-from-You-= pick-/260897401407?pt=3DLH_DefaultDomain_0&hash=3Ditem3cbeb26a3f&_uhb=3D1#ht_4373wt_1188
>>
>> There = seem to be a few left. They are sold as-is, but I found that the
>> majority of the ones= I bought worked OK. There may be other sellers on
>> eBay.
>= ;>
>>> I'd say go for it - I have built a couple of "MO-PA" = transmitters for
>>> 80/160m, they are really pleasant and rewa= rding projects with a distinct
>>> sound of their own. This is = especially true if you also key the
>>> oscillator.
>>=
>>
>> I have built recently a similar transmitter for 40= m, using a 6CL6 and
>> an 807. When I keyed the oscillator togeth= er with the PA, I couldn't
>> get it to behave properly, so I adde= d a switch to leave the oscillator
>> on and key only the cathode = of the PA. I only key the oscillator when
>> I want to draw some a= ttention with the home-brew sound!
>>
>> In general, I ha= ve had difficulty sourcing a HV transformer suitable
>> for an 807. In t= he past, I found that one can build a voltage doubler
>> or quadrupler, with modern electrolytics, it is a viable altern= ative.
>> The 6.3 V for the filaments I found I can get from a 6 V= transformer.
>> Hint: it's easy to add extra turns on a toroid ty= pe transformer :-)
>>
>> 73, Dimitris VK1SV
>
>
>= ;
>
>



 
<= /div> --131296447-1251172271-1355825158=:3315--